63 files changed, 1067 insertions, 6 deletions

diff --git a/debug/build.sh b/debug/build.sh
new file mode 100755
index 0000000..40da223
--- /dev/null
+++ b/debug/build.sh
@@ -0,0 +1,7 @@
+#!/bin/sh
+include='-I../libs -I../libs/pwyazh'
+cflags="-g -Wall -Wextra -Wno-unused-parameter $include"
+libs='-lm -lGL -lGLEW -lglfw'
+target='debug'
+set -x
+gcc -o $target $cflags $target.c $libs
diff --git a/debug/debug b/debug/debug
new file mode 100755
index 0000000..d516f24
--- /dev/null
+++ b/debug/debug
diff --git a/debug/debug.c b/debug/debug.c
new file mode 100644
index 0000000..8cddc16
--- /dev/null
+++ b/debug/debug.c
@@ -0,0 +1,62 @@
+#include <GL/glew.h>
+#include <GLFW/glfw3.h>
+
+#include "common.h"
+
+int main(void)
+{
+	state_t state = init_state(1600, 800, 1);
+	init_glfw(&state);
+	init_gl();
+
+	F32 vertices[] = {
+		-0.5f, -0.5f,
+		 0.0f,  0.5f,
+		 0.5f, -0.5f
+	};
+	U32 indices[] = {
+		0, 1, 2
+	};
+	U32 vao = 0, vbo = 0, ebo = 0;
+	glGenVertexArrays(1, &vao);
+	glGenBuffers(1, &ebo);
+	glGenBuffers(1, &vbo);
+	glBindVertexArray(vao);
+	glBindBuffer(GL_ARRAY_BUFFER, vbo);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
+	glEnableVertexAttribArray(0);
+	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(F32), 0);
+	glBindVertexArray(0);
+
+	add_shader("shader.vert", "shader.frag", 0);
+	U32 shader = find_shader("shader");
+	glUseProgram(shader);
+
+	glClearColor(0.16f, 0.16f, 0.16f, 1.0f);
+	glBindVertexArray(vao);
+
+	V2F offset = v2f(0.0f, 0.0f);
+	F32 time = 0.0f;
+
+	while (!glfwWindowShouldClose(state.window)) {
+		handle_glfw_events(state.window, &state.input);
+		F32 dt = lock_framerate(60);
+
+		/* update */
+		offset.x += 0.5f * dt;
+
+		/* render */
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+		glUniform2fv(glGetUniformLocation(shader, "offset"), 1, (F32 *)&offset);
+		glUniform1f(glGetUniformLocation(shader, "time"), time);
+		glDrawElements(GL_TRIANGLES, 3,  GL_UNSIGNED_INT, 0);
+
+		glfwSwapBuffers(state.window);
+
+		time += dt;
+	}
+
+	return 0;
+}
diff --git a/debug/shader.frag b/debug/shader.frag
new file mode 100644
index 0000000..fd25c5f
--- /dev/null
+++ b/debug/shader.frag
@@ -0,0 +1,12 @@
+#version 330 core
+
+in vec2 pos;
+
+out vec4 frag_color;
+
+uniform float time;
+
+void main()
+{
+	frag_color = vec4(sin(2.0 * time) * pos.x + 0.5, cos(2.0 * time) * pos.y + 0.5, 0.5, 1.0);
+}
diff --git a/debug/shader.vert b/debug/shader.vert
new file mode 100644
index 0000000..e37e212
--- /dev/null
+++ b/debug/shader.vert
@@ -0,0 +1,13 @@
+#version 330 core
+
+layout(location = 0) in vec2 apos;
+
+out vec2 pos;
+
+uniform vec2 offset;
+
+void main()
+{
+	pos = apos;
+	gl_Position = vec4(apos + offset, 0.0, 1.0);
+}
diff --git a/libs/common.h b/libs/common.h
index 72b44e7..08e753a 100644
--- a/libs/common.h
+++ b/libs/common.h
@@ -181,6 +181,7 @@ typedef struct {
 	GLFWwindow *window;
 	S32 width;
 	S32 height;
+	S32 debug;
 } state_t;
 
 Input input_init()
@@ -190,7 +191,7 @@ Input input_init()
 	return(input);
 }
 
-state_t init_state(S32 width, S32 height)
+state_t init_state(S32 width, S32 height, S32 debug)
 {
 	state_t state = {
 		.arena = arena_alloc(Megabytes(64)),
@@ -204,7 +205,8 @@ state_t init_state(S32 width, S32 height)
 			.pitch = 0.0f
 		},
 		.width = width,
-		.height = height
+		.height = height,
+		.debug = debug
 	};
 	return state;
 }
@@ -664,6 +666,8 @@ void init_glfw(state_t *state) {
 	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
 	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
 	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+	if (state->debug)
+		glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, 1);
 
 	glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
 	glfwWindowHint(GLFW_POSITION_X, xpos + monitor_width / 2.0f - state->width / 2.0f);
@@ -680,10 +684,91 @@ void init_glfw(state_t *state) {
 	glfwSwapInterval(0);
 }
 
+void gl_debug_output(GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar *message, const void *userParam)
+{
+	/* ignore these non-significant error codes */
+	if(id == 131169 || id == 131185 || id == 131218 || id == 131204)
+		return;
+	info("debug message (%d): %s", id, message);
+	switch (source) {
+	case GL_DEBUG_SOURCE_API:
+		info("source: api");
+		break;
+	case GL_DEBUG_SOURCE_WINDOW_SYSTEM:
+		info("source: window system");
+		break;
+	case GL_DEBUG_SOURCE_SHADER_COMPILER:
+		info("source: shader compiler");
+		break;
+	case GL_DEBUG_SOURCE_THIRD_PARTY:
+		info("source: third party");
+		break;
+	case GL_DEBUG_SOURCE_APPLICATION:
+		info("source: application");
+		break;
+	case GL_DEBUG_SOURCE_OTHER:
+		info("source: other");
+		break;
+	}
+	switch (type) {
+	case GL_DEBUG_TYPE_ERROR:
+		info("type: error");
+		break;
+	case GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR:
+		info("type: deprecated behaviour");
+		break;
+	case GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR:
+		info("type: undefined behaviour");
+		break; 
+	case GL_DEBUG_TYPE_PORTABILITY:
+		info("type: portability");
+		break;
+	case GL_DEBUG_TYPE_PERFORMANCE:
+		info("type: performance");
+		break;
+	case GL_DEBUG_TYPE_MARKER:
+		info("type: marker");
+		break;
+	case GL_DEBUG_TYPE_PUSH_GROUP:
+		info("type: push group");
+		break;
+	case GL_DEBUG_TYPE_POP_GROUP:
+		info("type: pop group");
+		break;
+	case GL_DEBUG_TYPE_OTHER:
+		info("type: other");
+		break;
+	}
+	switch (severity) {
+	case GL_DEBUG_SEVERITY_HIGH:
+		info("severity: high");
+		break;
+	case GL_DEBUG_SEVERITY_MEDIUM:
+		info("severity: medium");
+		break;
+	case GL_DEBUG_SEVERITY_LOW:
+		info("severity: low");
+		break;
+	case GL_DEBUG_SEVERITY_NOTIFICATION:
+		info("severity: notification");
+		break;
+	}
+	putc('\n', stdout);
+}
+
 void init_gl(void)
 {
 	if (glewInit() != GLEW_OK)
 		die("failed to initialize glew");
+	int flags;
+	glGetIntegerv(GL_CONTEXT_FLAGS, &flags);
+	if (flags & GL_CONTEXT_FLAG_DEBUG_BIT) {
+		info("debug context initialized successfully");
+		glEnable(GL_DEBUG_OUTPUT);
+		glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
+		glDebugMessageCallback(gl_debug_output, 0);
+		glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DONT_CARE, 0, 0, GL_TRUE);
+	}
 	glEnable(GL_DEPTH_TEST);
 }
 
@@ -1056,4 +1141,42 @@ F32 lerp(F32 a, F32 b, F32 f)
     return a + f * (b - a);
 }
 
+U32 check_gl_errors_(const char *file, int line)
+{
+	U32 code;
+	while ((code = glGetError()) != GL_NO_ERROR) {
+		char *error;
+		switch (code) {
+		case GL_INVALID_ENUM:
+			error = "invalid enum";
+			break;
+		case GL_INVALID_VALUE:
+			error = "invalid value";
+			break;
+		case GL_INVALID_OPERATION:
+			error = "invalid operation";
+			break;
+		case GL_STACK_OVERFLOW:
+			error = "stack overflow";
+			break;
+		case GL_STACK_UNDERFLOW:
+			error = "stack underflow";
+			break;
+		case GL_OUT_OF_MEMORY:
+			error = "out of memory";
+			break;
+		case GL_INVALID_FRAMEBUFFER_OPERATION:
+			error = "invalid framebuffer operation";
+			break;
+		default:
+			error = "undefined error";
+			break;
+		}
+		info("%s:%d: %s", file, line, error);
+	}
+	return code;
+}
+
+#define check_gl_errors() check_gl_errors_(__FILE__, __LINE__)
+
 #endif /* COMMON_H */
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/background.frag b/pbr/ibl_irradiance/background.frag
index e3891eb..e3891eb 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/background.frag
+++ b/pbr/ibl_irradiance/background.frag
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/background.vert b/pbr/ibl_irradiance/background.vert
index 25b9778..25b9778 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/background.vert
+++ b/pbr/ibl_irradiance/background.vert
diff --git a/pbr/2.1.2.ibl_irradiance/build.sh b/pbr/ibl_irradiance/build.sh
index fdecd76..fdecd76 100755
--- a/pbr/2.1.2.ibl_irradiance/build.sh
+++ b/pbr/ibl_irradiance/build.sh
diff --git a/pbr/2.1.2.ibl_irradiance/convolution.frag b/pbr/ibl_irradiance/convolution.frag
index 69ce8af..69ce8af 100644
--- a/pbr/2.1.2.ibl_irradiance/convolution.frag
+++ b/pbr/ibl_irradiance/convolution.frag
diff --git a/pbr/2.1.2.ibl_irradiance/convolution.vert b/pbr/ibl_irradiance/convolution.vert
index 8f8862e..8f8862e 100644
--- a/pbr/2.1.2.ibl_irradiance/convolution.vert
+++ b/pbr/ibl_irradiance/convolution.vert
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/cubemap.frag b/pbr/ibl_irradiance/cubemap.frag
index 349347a..349347a 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/cubemap.frag
+++ b/pbr/ibl_irradiance/cubemap.frag
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/cubemap.vert b/pbr/ibl_irradiance/cubemap.vert
index 8f8862e..8f8862e 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/cubemap.vert
+++ b/pbr/ibl_irradiance/cubemap.vert
diff --git a/pbr/1.1.lighting/hdr.frag b/pbr/ibl_irradiance/hdr.frag
index 01650ae..01650ae 100644
--- a/pbr/1.1.lighting/hdr.frag
+++ b/pbr/ibl_irradiance/hdr.frag
diff --git a/pbr/1.1.lighting/hdr.vert b/pbr/ibl_irradiance/hdr.vert
index 1b953d7..1b953d7 100644
--- a/pbr/1.1.lighting/hdr.vert
+++ b/pbr/ibl_irradiance/hdr.vert
diff --git a/pbr/2.1.2.ibl_irradiance/ibl_irradiance b/pbr/ibl_irradiance/ibl_irradiance
index 4561ae2..aee47cb 100755
--- a/pbr/2.1.2.ibl_irradiance/ibl_irradiance
+++ b/pbr/ibl_irradiance/ibl_irradiance
diff --git a/pbr/2.1.2.ibl_irradiance/ibl_irradiance.c b/pbr/ibl_irradiance/ibl_irradiance.c
index e6f1390..921c60d 100644
--- a/pbr/2.1.2.ibl_irradiance/ibl_irradiance.c
+++ b/pbr/ibl_irradiance/ibl_irradiance.c
@@ -193,14 +193,12 @@ int main(void)
 				mesh_draw(sphere);
 			}
 		}
-
 		for (U32 i = 0; i < (sizeof(lights) / sizeof(lights[0])); i++) {
 			MAT4 model = mat4_make_scale(v3f(0.5f, 0.5f, 0.5f));
 			model = mat4_translate(model, lights[i].position);
 			shader_set_mat4fv(shader, "model", model);
 			mesh_draw(sphere);
 		}
-
 		glUseProgram(0);
 
 		shader = find_shader("background");
@@ -208,7 +206,7 @@ int main(void)
 		shader_set_mat4fv(shader, "projection", projection);
 		shader_set_mat4fv(shader, "view", view);
 		glActiveTexture(GL_TEXTURE0);
-		glBindTexture(GL_TEXTURE_CUBE_MAP, irradiance_map);
+		glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
 		mesh_draw(cube);
 		glUseProgram(0);
 
@@ -216,7 +214,7 @@ int main(void)
 		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
 		shader = find_shader("hdr");
-		if (!shader) die("failed to find hdr shader!");
+		if (!shader) die("!");
 		glUseProgram(shader);
 		glBindTexture(GL_TEXTURE_2D, hdr_colorbuffer);
 		shader_set_mat4fv(shader, "model", mat4_identity());
diff --git a/pbr/2.1.2.ibl_irradiance/pbr.frag b/pbr/ibl_irradiance/pbr.frag
index 88cf01d..88cf01d 100644
--- a/pbr/2.1.2.ibl_irradiance/pbr.frag
+++ b/pbr/ibl_irradiance/pbr.frag
diff --git a/pbr/1.1.lighting/pbr.vert b/pbr/ibl_irradiance/pbr.vert
index e6e3800..e6e3800 100644
--- a/pbr/1.1.lighting/pbr.vert
+++ b/pbr/ibl_irradiance/pbr.vert
diff --git a/pbr/2.1.2.ibl_irradiance/background.frag b/pbr/ibl_irradiance_conversion/background.frag
index e3891eb..e3891eb 100644
--- a/pbr/2.1.2.ibl_irradiance/background.frag
+++ b/pbr/ibl_irradiance_conversion/background.frag
diff --git a/pbr/2.1.2.ibl_irradiance/background.vert b/pbr/ibl_irradiance_conversion/background.vert
index 25b9778..25b9778 100644
--- a/pbr/2.1.2.ibl_irradiance/background.vert
+++ b/pbr/ibl_irradiance_conversion/background.vert
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/build.sh b/pbr/ibl_irradiance_conversion/build.sh
index 834030a..834030a 100755
--- a/pbr/2.1.1.ibl_irradiance_conversion/build.sh
+++ b/pbr/ibl_irradiance_conversion/build.sh
diff --git a/pbr/2.1.2.ibl_irradiance/cubemap.frag b/pbr/ibl_irradiance_conversion/cubemap.frag
index 349347a..349347a 100644
--- a/pbr/2.1.2.ibl_irradiance/cubemap.frag
+++ b/pbr/ibl_irradiance_conversion/cubemap.frag
diff --git a/pbr/2.1.2.ibl_irradiance/cubemap.vert b/pbr/ibl_irradiance_conversion/cubemap.vert
index 8f8862e..8f8862e 100644
--- a/pbr/2.1.2.ibl_irradiance/cubemap.vert
+++ b/pbr/ibl_irradiance_conversion/cubemap.vert
diff --git a/pbr/1.2.textured/hdr.frag b/pbr/ibl_irradiance_conversion/hdr.frag
index 01650ae..01650ae 100644
--- a/pbr/1.2.textured/hdr.frag
+++ b/pbr/ibl_irradiance_conversion/hdr.frag
diff --git a/pbr/1.2.textured/hdr.vert b/pbr/ibl_irradiance_conversion/hdr.vert
index 1b953d7..1b953d7 100644
--- a/pbr/1.2.textured/hdr.vert
+++ b/pbr/ibl_irradiance_conversion/hdr.vert
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/ibl_irradiance_conversion b/pbr/ibl_irradiance_conversion/ibl_irradiance_conversion
index cc43012..cc43012 100755
--- a/pbr/2.1.1.ibl_irradiance_conversion/ibl_irradiance_conversion
+++ b/pbr/ibl_irradiance_conversion/ibl_irradiance_conversion
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/ibl_irradiance_conversion.c b/pbr/ibl_irradiance_conversion/ibl_irradiance_conversion.c
index 0ffbe7c..0ffbe7c 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/ibl_irradiance_conversion.c
+++ b/pbr/ibl_irradiance_conversion/ibl_irradiance_conversion.c
diff --git a/pbr/1.1.lighting/pbr.frag b/pbr/ibl_irradiance_conversion/pbr.frag
index db9edea..db9edea 100644
--- a/pbr/1.1.lighting/pbr.frag
+++ b/pbr/ibl_irradiance_conversion/pbr.frag
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/pbr.vert b/pbr/ibl_irradiance_conversion/pbr.vert
index e6e3800..e6e3800 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/pbr.vert
+++ b/pbr/ibl_irradiance_conversion/pbr.vert
diff --git a/pbr/ibl_specular/background.frag b/pbr/ibl_specular/background.frag
new file mode 100644
index 0000000..e3891eb
--- /dev/null
+++ b/pbr/ibl_specular/background.frag
@@ -0,0 +1,17 @@
+#version 330 core
+
+in vert_t {
+	vec3 position;
+} vert;
+
+out vec4 frag_color;
+
+uniform samplerCube cubemap;
+
+void main(void)
+{
+	vec3 color = texture(cubemap, vert.position).rgb;
+	color /= color + vec3(1.0);
+	color = pow(color, vec3(1.0 / 2.2));
+	frag_color = vec4(color, 1.0);
+}
diff --git a/pbr/ibl_specular/background.vert b/pbr/ibl_specular/background.vert
new file mode 100644
index 0000000..25b9778
--- /dev/null
+++ b/pbr/ibl_specular/background.vert
@@ -0,0 +1,19 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+
+out vert_t {
+	vec3 position;
+} vert;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+void main(void)
+{
+	vert.position = position;
+	
+	mat4 rotate_view = mat4(mat3(view));
+	vec4 clip_position = projection * rotate_view * vec4(position, 1.0);
+	gl_Position = clip_position.xyww;
+}
diff --git a/pbr/ibl_specular/brdf.frag b/pbr/ibl_specular/brdf.frag
new file mode 100644
index 0000000..6e7cf5b
--- /dev/null
+++ b/pbr/ibl_specular/brdf.frag
@@ -0,0 +1,98 @@
+#version 330 core
+
+in vert_t {
+	vec2 tex_coords;
+} vert;
+
+out vec2 frag_color;
+
+const float PI = 3.14159265359;
+
+float radical_inverse_vdc(uint bits)
+{
+	bits = (bits << 16u) | (bits >> 16u);
+	bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
+	bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
+	bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
+	bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
+	return float(bits) * 2.3283064365386963e-10; // / 0x100000000
+}
+
+vec2 hammersley(uint i, uint n)
+{
+	return vec2(float(i) / float(n), radical_inverse_vdc(i));
+}
+
+vec3 importance_sample_ggx(vec2 xi, vec3 n, float roughness)
+{
+	float a = roughness * roughness;
+	
+	float phi = 2.0 * PI * xi.x;
+	float cos_theta = sqrt((1.0 - xi.y) / (1.0 + (a * a - 1.0) * xi.y));
+	float sin_theta = sqrt(1.0 - cos_theta * cos_theta);
+	
+	vec3 h;
+	h.x = cos(phi) * sin_theta;
+	h.y = sin(phi) * sin_theta;
+	h.z = cos_theta;
+	
+	vec3 up = abs(n.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
+	vec3 tangent = normalize(cross(up, n));
+	vec3 bitangent = cross(n, tangent);
+	
+	vec3 samplevec = tangent * h.x + bitangent * h.y + n * h.z;
+	return normalize(samplevec);
+}
+
+float geometry_schlick_ggx(float ndotv, float roughness)
+{
+	float a = roughness;
+	float k = (a * a) / 2.0;
+	float nom = ndotv;
+	float denom = ndotv * (1.0 - k) + k;
+	return nom / denom;
+}
+
+float geometry_smith(vec3 n, vec3 v, vec3 l, float roughness)
+{
+	float ndotv = max(dot(n, v), 0.0);
+	float ndotl = max(dot(n, l), 0.0);
+	float ggx1 = geometry_schlick_ggx(ndotl, roughness);
+	float ggx2 = geometry_schlick_ggx(ndotv, roughness);
+	return ggx1 * ggx2;
+}
+
+vec2 integrate_brdf(float ndotv, float roughness)
+{
+	vec3 v;
+	v.x = sqrt(1.0 - ndotv * ndotv);
+	v.y = 0.0;
+	v.z = ndotv;
+	float a = 0.0;
+	float b = 0.0;
+	vec3 n = vec3(0.0, 0.0, 1.0);
+	uint sample_count = 1024u;
+	for (uint i = 0u; i < sample_count; i++) {
+		vec2 xi = hammersley(i, sample_count);
+		vec3 h = importance_sample_ggx(xi, n, roughness);
+		vec3 l = normalize(2.0 * dot(v, h) * h - v);
+		float ndotl = max(l.z, 0.0);
+		float ndoth = max(h.z, 0.0);
+		float vdoth = max(dot(v, h), 0.0);
+		if (ndotl > 0.0) {
+			float g = geometry_smith(n, v, l, roughness);
+			float g_vis = (g * vdoth) / (ndoth * ndotv);
+			float fc = pow(1.0 - vdoth, 5.0);
+			a += (1.0 - fc) * g_vis;
+			b += fc * g_vis;
+		}
+	}
+	a /= float(sample_count);
+	b /= float(sample_count);
+	return vec2(a, b);
+}
+
+void main()
+{
+	frag_color = integrate_brdf(vert.tex_coords.x, vert.tex_coords.y);
+}
diff --git a/pbr/ibl_specular/brdf.vert b/pbr/ibl_specular/brdf.vert
new file mode 100644
index 0000000..fd86ecc
--- /dev/null
+++ b/pbr/ibl_specular/brdf.vert
@@ -0,0 +1,13 @@
+#version 330 core
+layout(location = 0) in vec3 position;
+layout(location = 2) in vec2 tex_coords;
+
+out vert_t {
+	vec2 tex_coords;
+} vert;
+
+void main()
+{
+	vert.tex_coords = tex_coords;
+	gl_Position = vec4(position, 1.0);
+}
diff --git a/pbr/ibl_specular/build.sh b/pbr/ibl_specular/build.sh
new file mode 100755
index 0000000..5ed5193
--- /dev/null
+++ b/pbr/ibl_specular/build.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+. ../../config
+TARGET='ibl_specular'
+set -x
+gcc -o $TARGET $CFLAGS $INCLUDE $LFLAGS $TARGET.c $LIBS
diff --git a/pbr/ibl_specular/convolution.frag b/pbr/ibl_specular/convolution.frag
new file mode 100644
index 0000000..69ce8af
--- /dev/null
+++ b/pbr/ibl_specular/convolution.frag
@@ -0,0 +1,33 @@
+#version 330 core
+
+in vert_t {
+	vec3 position;
+} vert;
+
+out vec4 frag_color;
+
+uniform samplerCube cubemap;
+
+const float PI = 3.14159265359;
+
+void main(void)
+{
+	vec3 normal = normalize(vert.position);
+	vec3 up = vec3(0.0, 1.0, 0.0);
+	vec3 right = cross(up, normal);
+	up = cross(normal, right);
+
+	vec3 irradiance = vec3(0.0);
+	float delta = 0.025;
+	int nsamples = 0;
+	for (float phi = 0.0; phi < 2.0 * PI; phi += delta) {
+		for (float theta = 0.0; theta < 0.5 * PI; theta += delta) {
+			vec3 tangent = vec3(sin(theta) * cos(phi), sin(theta) * sin(phi), cos(theta));
+			vec3 v = tangent.x * right + tangent.y * up + tangent.z * normal;
+			irradiance += texture(cubemap, v).rgb * cos(theta) * sin(theta);
+			nsamples++;
+		}
+	}
+	irradiance *= PI / nsamples;
+	frag_color = vec4(irradiance, 1.0);
+}
diff --git a/pbr/ibl_specular/convolution.vert b/pbr/ibl_specular/convolution.vert
new file mode 100644
index 0000000..8f8862e
--- /dev/null
+++ b/pbr/ibl_specular/convolution.vert
@@ -0,0 +1,17 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+
+out vert_t {
+	vec3 position;
+} vert;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+void main(void)
+{
+	gl_Position = projection * view * vec4(position, 1.0);
+
+	vert.position = position;
+}
diff --git a/pbr/ibl_specular/cubemap.frag b/pbr/ibl_specular/cubemap.frag
new file mode 100644
index 0000000..349347a
--- /dev/null
+++ b/pbr/ibl_specular/cubemap.frag
@@ -0,0 +1,25 @@
+#version 330 core
+
+in vert_t {
+	vec3 position;
+} vert;
+
+out vec4 frag_color;
+
+uniform sampler2D map;
+
+const vec2 inv_atan = vec2(0.1591, 0.3183);
+vec2 sample_spherical_map(vec3 v)
+{
+	vec2 uv = vec2(atan(v.z, v.x), asin(v.y));
+	uv *= inv_atan;
+	uv += 0.5;
+	return uv;
+}
+
+void main(void)
+{
+	vec2 uv = sample_spherical_map(normalize(vert.position));
+	vec3 color = texture(map, uv).rgb;
+	frag_color = vec4(color, 1.0);
+}
diff --git a/pbr/ibl_specular/cubemap.vert b/pbr/ibl_specular/cubemap.vert
new file mode 100644
index 0000000..8f8862e
--- /dev/null
+++ b/pbr/ibl_specular/cubemap.vert
@@ -0,0 +1,17 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+
+out vert_t {
+	vec3 position;
+} vert;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+void main(void)
+{
+	gl_Position = projection * view * vec4(position, 1.0);
+
+	vert.position = position;
+}
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/hdr.frag b/pbr/ibl_specular/hdr.frag
index 01650ae..01650ae 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/hdr.frag
+++ b/pbr/ibl_specular/hdr.frag
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/hdr.vert b/pbr/ibl_specular/hdr.vert
index 1b953d7..1b953d7 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/hdr.vert
+++ b/pbr/ibl_specular/hdr.vert
diff --git a/pbr/ibl_specular/ibl_specular b/pbr/ibl_specular/ibl_specular
new file mode 100755
index 0000000..e4466f5
--- /dev/null
+++ b/pbr/ibl_specular/ibl_specular
diff --git a/pbr/ibl_specular/ibl_specular.c b/pbr/ibl_specular/ibl_specular.c
new file mode 100644
index 0000000..5692505
--- /dev/null
+++ b/pbr/ibl_specular/ibl_specular.c
@@ -0,0 +1,307 @@
+#include "GL/glew.h"
+#include "GLFW/glfw3.h"
+#include "common.h"
+
+int main(void)
+{
+	state_t state = init_state(1600, 800);
+
+	init_glfw(&state);
+	init_gl();
+	glDepthFunc(GL_LEQUAL);
+	glEnable(GL_TEXTURE_CUBE_MAP_SEAMLESS);
+
+	/* meshes */
+	Mesh *cube = mesh_load_obj(state.arena, "../../data/models/cube.obj");
+	Mesh *sphere = mesh_load_obj(state.arena, "../../data/models/sphere.obj");
+	Mesh *quad = mesh_gen_quad(state.arena);
+
+	/* shaders */
+	add_shader("pbr.vert", "pbr.frag", 0);
+	add_shader("hdr.vert", "hdr.frag", 0);
+	add_shader("cubemap.vert", "cubemap.frag", 0);
+	add_shader("background.vert", "background.frag", 0);
+	add_shader("convolution.vert", "convolution.frag", 0);
+	add_shader("prefilter.vert", "prefilter.frag", 0);
+	add_shader("brdf.vert", "brdf.frag", 0);
+
+	U32 shader = find_shader("pbr");
+	glUseProgram(shader);
+	shader_set_1i(shader, "irradiance_map", 0);
+	shader_set_1i(shader, "prefilter_map", 1);
+	shader_set_1i(shader, "brdf_lut", 2);
+	glUseProgram(0);
+
+	light_t lights[4] = {
+		{{-10.0f, 0.0f, 20.0f}, {300.0f, 300.0f, 300.0f}},
+		{{-5.0f,  0.0f, 20.0f}, {300.0f, 300.0f, 300.0f}},
+		{{ 5.0f,  0.0f, 20.0f}, {300.0f, 300.0f, 300.0f}},
+		{{ 10.0f, 0.0f, 20.0f}, {300.0f, 300.0f, 300.0f}},
+	};
+
+	/* textures */
+	U32 textures[] = {
+		load_hdr_texture("../../data/textures/loigerwiesen.hdr"),
+		load_hdr_texture("../../data/textures/wells.hdr")
+	};
+	U32 hdr_texture = 1;
+
+	/* framebuffers */
+	U32 hdr_fbo, hdr_colorbuffer, hdr_rbo;
+	glGenFramebuffers(1, &hdr_fbo);
+	glGenTextures(1, &hdr_colorbuffer);
+	glBindTexture(GL_TEXTURE_2D, hdr_colorbuffer);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA16F, state.width, state.height, 0, GL_RGBA, GL_FLOAT, 0);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	glGenRenderbuffers(1, &hdr_rbo);
+	glBindRenderbuffer(GL_RENDERBUFFER, hdr_rbo);
+	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, state.width, state.height);
+	glBindFramebuffer(GL_FRAMEBUFFER, hdr_fbo);
+	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, hdr_colorbuffer, 0);
+	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, hdr_rbo);
+	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+		die("failed to create framebuffer");
+	glBindRenderbuffer(GL_RENDERBUFFER, 0);
+	glBindTexture(GL_TEXTURE_2D, 0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	U32 capture_fbo, capture_rbo;
+	glGenFramebuffers(1, &capture_fbo);
+	glGenRenderbuffers(1, &capture_rbo);
+	glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+	glBindRenderbuffer(GL_RENDERBUFFER, capture_rbo);
+	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 512, 512);
+	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, capture_rbo);
+	if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+		die("failed to create framebuffer");
+	glBindRenderbuffer(GL_RENDERBUFFER, 0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	U32 cubemap;
+	glGenTextures(1, &cubemap);
+	glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+	for (U32 i = 0; i < 6; i++)
+		glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 512, 512, 0, GL_RGB, GL_FLOAT, 0);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+	MAT4 capture_projection = perspective(90.0f, 1.0f, 0.1f, 10.0f);
+	V3F capture_origin = {0};
+	MAT4 capture_views[6] = {
+		look_at(capture_origin, v3f( 1.0f,  0.0f,  0.0f), v3f(0.0f, -1.0f,  0.0f)),
+		look_at(capture_origin, v3f(-1.0f,  0.0f,  0.0f), v3f(0.0f, -1.0f,  0.0f)),
+		look_at(capture_origin, v3f( 0.0f,  1.0f,  0.0f), v3f(0.0f,  0.0f,  1.0f)),
+		look_at(capture_origin, v3f( 0.0f, -1.0f,  0.0f), v3f(0.0f,  0.0f, -1.0f)),
+		look_at(capture_origin, v3f( 0.0f,  0.0f,  1.0f), v3f(0.0f, -1.0f,  0.0f)),
+		look_at(capture_origin, v3f( 0.0f,  0.0f, -1.0f), v3f(0.0f, -1.0f,  0.0f)),
+	};
+
+	glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+	shader = find_shader("cubemap");
+	if (!shader) die("waht");
+	glUseProgram(shader);
+	shader_set_mat4fv(shader, "projection", capture_projection);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_2D, textures[hdr_texture]);
+
+	glViewport(0, 0, 512, 512);
+	for (U32 i = 0; i < 6; i++) {
+		shader_set_mat4fv(shader, "view", capture_views[i]);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, cubemap, 0);
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+		mesh_draw(cube);
+	}
+	glUseProgram(0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+	glGenerateMipmap(GL_TEXTURE_CUBE_MAP);
+
+	U32 irradiance_map;
+	glGenTextures(1, &irradiance_map);
+	glBindTexture(GL_TEXTURE_CUBE_MAP, irradiance_map);
+	for (U32 i = 0; i < 6; i++)
+		glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 32, 32, 0, GL_RGB, GL_FLOAT, 0);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	glBindTexture(GL_TEXTURE_CUBE_MAP, 0);
+
+	glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+	glBindRenderbuffer(GL_RENDERBUFFER, capture_rbo);
+	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 32, 32);
+	glBindRenderbuffer(GL_RENDERBUFFER, 0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+	shader = find_shader("convolution");
+	glUseProgram(shader);
+	shader_set_mat4fv(shader, "projection", capture_projection);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+	glViewport(0, 0, 32, 32);
+	for (U32 i = 0; i < 6; i++) {
+		shader_set_mat4fv(shader, "view", capture_views[i]);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, irradiance_map, 0);
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+		mesh_draw(cube);
+	}
+	glUseProgram(0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	U32 prefilter_map;
+	glGenTextures(1, &prefilter_map);
+	glBindTexture(GL_TEXTURE_CUBE_MAP, prefilter_map);
+	for (U32 i = 0; i < 6; i++)
+		glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB16F, 128, 128, 0, GL_RGB, GL_FLOAT, 0);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
+	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	glGenerateMipmap(GL_TEXTURE_CUBE_MAP);
+
+	shader = find_shader("prefilter");
+	glUseProgram(shader);
+	glActiveTexture(GL_TEXTURE0);
+	glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+	shader_set_mat4fv(shader, "projection", capture_projection);
+	glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+	U32 mipmap_levels = 5;
+	for (U32 mip = 0; mip < mipmap_levels; mip++) {
+		U32 width = 128 * pow(0.5, mip);
+		U32 height = width;
+		glBindRenderbuffer(GL_RENDERBUFFER, capture_rbo);
+		glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, width, height);
+		glViewport(0, 0, width, height);
+		float roughness = (float)mip / (float)(mipmap_levels - 1);
+		shader_set_1f(shader, "roughness", roughness);
+		for (U32 i = 0; i < 6; i++) {
+			shader_set_mat4fv(shader, "view", capture_views[i]);
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, prefilter_map, mip);
+			glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+			mesh_draw(cube);
+		}
+	}
+	glUseProgram(0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	U32 brdf_lut_texture;
+	glGenTextures(1, &brdf_lut_texture);
+	glBindTexture(GL_TEXTURE_2D, brdf_lut_texture);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RG16F, 512, 512, 0, GL_RG, GL_FLOAT, 0);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+	glBindRenderbuffer(GL_RENDERBUFFER, capture_rbo);
+	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, 512, 512);
+	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, brdf_lut_texture, 0);
+	glViewport(0, 0, 512, 512);
+	shader = find_shader("brdf");
+	assert(shader);
+	glUseProgram(shader);
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+	mesh_draw(quad);
+	glUseProgram(0);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	glViewport(0, 0, state.width, state.height);
+
+	F32 time = 0;
+
+	while (!glfwWindowShouldClose(state.window)) {
+		handle_glfw_events(state.window, &state.input);
+		F32 dt = lock_framerate(60);
+		fps_info(dt, 10);
+
+		/* update */
+		update_camera_first_person(&state.camera, &state.input, dt, 2.0f);
+		F32 limit = 4.0f;
+		for (U32 i = 0; i < (sizeof(lights) / sizeof(lights[0])); i++)
+			lights[i].position.y = sinf(time + i) * limit;
+		time += dt;
+
+		/* render */
+		F32 ar = (F32)state.width / (F32)state.height;
+		MAT4 projection = camera_persp(state.camera, ar);
+		MAT4 view = get_view_matrix(&state.camera);
+
+		glClearColor(0.16f, 0.16f, 0.16f, 1.0f);
+
+		glBindFramebuffer(GL_FRAMEBUFFER, hdr_fbo);
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+		shader = find_shader("pbr");
+		glUseProgram(shader);
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_CUBE_MAP, irradiance_map);
+		glActiveTexture(GL_TEXTURE1);
+		glBindTexture(GL_TEXTURE_CUBE_MAP, prefilter_map);
+		glActiveTexture(GL_TEXTURE2);
+		glBindTexture(GL_TEXTURE_2D, brdf_lut_texture);
+		shader_set_mat4fv(shader, "projection", projection);
+		shader_set_mat4fv(shader, "view", view);
+		shader_set_3fv(shader, "camera", state.camera.pos);
+		shader_set_3fv(shader, "color", v3f(0.04, 0.04, 0.04));
+		shader_set_1f(shader, "ao", 1.0f);
+		for (U32 i = 0; i < (sizeof(lights) / sizeof(lights[0])); i++) {
+			char str[512];
+			snprintf(str, 512, "lights[%d].position", i);
+			shader_set_3fv(shader, str, lights[i].position);
+			snprintf(str, 512, "lights[%d].color", i);
+			shader_set_3fv(shader, str, lights[i].color);
+		}
+		S32 rows = 7;
+		S32 cols = 7;
+		F32 offset = 3.0f;
+		for (S32 row = 0; row < rows; row++) {
+			shader_set_1f(shader, "metallic", (F32)row / (F32)rows);
+			for (S32 col = 0; col < cols; col++) {
+				shader_set_1f(shader, "roughness", clamp(0.05f, (F32)col / (F32)cols, 1.0f));
+				V3F pos = {(col - cols / 2.0f) * offset, (row - rows / 2.0f) * offset, 0.0f};
+				MAT4 model = mat4_make_translate(pos);
+				shader_set_mat4fv(shader, "model", model);
+				mesh_draw(cube);
+			}
+		}
+		for (U32 i = 0; i < (sizeof(lights) / sizeof(lights[0])); i++) {
+			MAT4 model = mat4_make_scale(v3f(0.5f, 0.5f, 0.5f));
+			model = mat4_translate(model, lights[i].position);
+			shader_set_mat4fv(shader, "model", model);
+			mesh_draw(sphere);
+		}
+		glUseProgram(0);
+
+		shader = find_shader("background");
+		glUseProgram(shader);
+		shader_set_mat4fv(shader, "projection", projection);
+		shader_set_mat4fv(shader, "view", view);
+		glActiveTexture(GL_TEXTURE0);
+		glBindTexture(GL_TEXTURE_CUBE_MAP, cubemap);
+		mesh_draw(cube);
+		glUseProgram(0);
+
+		glBindFramebuffer(GL_FRAMEBUFFER, 0);
+		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+		shader = find_shader("hdr");
+		if (!shader) die("!");
+		glUseProgram(shader);
+		glBindTexture(GL_TEXTURE_2D, hdr_colorbuffer);
+		shader_set_mat4fv(shader, "model", mat4_identity());
+		mesh_draw(quad);
+		glUseProgram(0);
+
+		glfwSwapBuffers(state.window);
+	}
+
+	return 0;
+}
diff --git a/pbr/ibl_specular/pbr.frag b/pbr/ibl_specular/pbr.frag
new file mode 100644
index 0000000..3ed2018
--- /dev/null
+++ b/pbr/ibl_specular/pbr.frag
@@ -0,0 +1,131 @@
+#version 330 core
+
+in vert_t {
+	vec3 position;
+	vec3 normal;
+} vert;
+
+out vec4 frag_color;
+
+uniform vec3 camera;
+
+uniform vec3 color;
+uniform float metallic;
+uniform float roughness;
+uniform float ao;
+
+uniform samplerCube irradiance_map;
+uniform samplerCube prefilter_map;
+uniform sampler2D brdf_lut;
+
+struct light_t {
+	vec3 position;
+	vec3 color;
+};
+
+const int light_count = 4;
+uniform light_t lights[light_count];
+
+const float PI = 3.14159265358; 
+
+vec3 fresnel_schlick(float costheta, vec3 f0)
+{
+	return f0 + (1.0 - f0) * pow(1.0 - costheta, 5.0);
+}
+
+vec3 fresnel_schlick_roughness(float costheta, vec3 f0, float roughness)
+{
+    return f0 + (max(vec3(1.0 - roughness), f0) - f0) * pow(clamp(1.0 - costheta, 0.0, 1.0), 5.0);
+}   
+
+float distribution_ggx(vec3 n, vec3 h, float roughness)
+{
+	float a = roughness * roughness;
+	float a2 = a * a;
+	float ndoth = max(dot(n, h), 0.0);
+	float ndoth2 = ndoth * ndoth;
+
+	float num = a2;
+	float denom = (ndoth2 * (a2 - 1.0) + 1.0);
+	denom = PI * denom * denom;
+
+	return num / denom;
+}
+
+float geometry_schlick_ggx(float ndotv, float roughness)
+{
+	float r = roughness + 1.0;
+	float k = r * r / 8.0;
+
+	float num = ndotv;
+	float denom = ndotv * (1.0 - k) + k;
+	
+	return num / denom;
+}
+
+float geometry_smith(vec3 n, vec3 v, vec3 l, float roughness)
+{
+	float ndotv = max(dot(n, v), 0.0);
+	float ndotl = max(dot(n, l), 0.0);
+	float ggx2 = geometry_schlick_ggx(ndotv, roughness);
+	float ggx1 = geometry_schlick_ggx(ndotl, roughness);
+
+	return ggx1 * ggx2;
+}
+
+void main(void)
+{
+	vec3 n = vert.normal;
+	vec3 v = normalize(camera - vert.position);
+	vec3 r = reflect(-v, n);
+
+	vec3 f0 = vec3(0.04);
+	f0 = mix(f0, color, metallic);
+
+	vec3 lo = vec3(0.0);
+	for (int i = 0; i < light_count; i++) {
+		vec3 l = normalize(lights[i].position - vert.position);
+		vec3 h = normalize(v + l);
+		float ndotv = max(dot(n, v), 0.0);
+		float ndotl = max(dot(n, l), 0.0);
+
+		float distance = length(lights[i].position - vert.position);
+		float attenuation = 1.0 / (distance * distance);
+
+		vec3 radiance = lights[i].color * attenuation;
+
+		vec3 f = fresnel_schlick(max(dot(h, v), 0.0), f0);
+
+		float ndf = distribution_ggx(n, h, roughness);
+		float g = geometry_smith(n, v, l, roughness);
+
+		vec3 numerator = ndf * g * f;
+		float denominator = 4.0 * ndotv * ndotl;
+		vec3 specular = numerator / max(denominator, 0.001);
+
+		vec3 ks = f;
+		vec3 kd = vec3(1.0) - ks;
+
+		kd *= 1.0 - metallic;
+
+		lo += (kd * color / PI + specular) * radiance * ndotl;
+	}
+
+	vec3 f = fresnel_schlick_roughness(max(dot(n, v), 0.0), f0, roughness);
+
+	vec3 ks = f;
+	vec3 kd = 1.0 - ks;
+	kd *= 1.0 - metallic;
+
+	vec3 irradiance = texture(irradiance_map, n).rgb;
+	vec3 diffuse = irradiance * color;
+
+	float max_reflection_lod = 4.0;
+	vec3 prefiltered = textureLod(prefilter_map, r, roughness * max_reflection_lod).rgb;
+	vec2 brdf = texture(brdf_lut, vec2(max(dot(n, v), 0.0), roughness)).rg;
+	vec3 specular = prefiltered * (f * brdf.x + brdf.y);
+
+	vec3 ambient = (kd * diffuse + specular)* ao;
+
+	frag_color = vec4(ambient + lo, 1.0);
+}
diff --git a/pbr/2.1.2.ibl_irradiance/pbr.vert b/pbr/ibl_specular/pbr.vert
index e6e3800..e6e3800 100644
--- a/pbr/2.1.2.ibl_irradiance/pbr.vert
+++ b/pbr/ibl_specular/pbr.vert
diff --git a/pbr/ibl_specular/prefilter.frag b/pbr/ibl_specular/prefilter.frag
new file mode 100644
index 0000000..5359c58
--- /dev/null
+++ b/pbr/ibl_specular/prefilter.frag
@@ -0,0 +1,91 @@
+#version 330 core
+
+in vert_t {
+	vec3 position;
+} vert;
+
+out vec4 frag_color;
+
+uniform samplerCube cubemap;
+uniform float roughness;
+
+const float PI = 3.14159265359;
+
+float distribution_ggx(vec3 n, vec3 h, float roughness)
+{
+	float a = roughness * roughness;
+	float a2 = a * a;
+	float ndoth = max(dot(n, h), 0.0);
+	float ndoth2 = ndoth * ndoth;
+	float nom = a2;
+	float denom = (ndoth2 * (a2 - 1.0) + 1.0);
+	denom = PI * denom * denom;
+	return nom / denom;
+}
+
+float radical_inverse_vdc(uint bits)
+{
+	bits = (bits << 16u) | (bits >> 16u);
+	bits = ((bits & 0x55555555u) << 1u) | ((bits & 0xAAAAAAAAu) >> 1u);
+	bits = ((bits & 0x33333333u) << 2u) | ((bits & 0xCCCCCCCCu) >> 2u);
+	bits = ((bits & 0x0F0F0F0Fu) << 4u) | ((bits & 0xF0F0F0F0u) >> 4u);
+	bits = ((bits & 0x00FF00FFu) << 8u) | ((bits & 0xFF00FF00u) >> 8u);
+	return float(bits) * 2.3283064365386963e-10; // / 0x100000000
+}
+
+vec2 hammersley(uint i, uint n)
+{
+	return vec2(float(i) / float(n), radical_inverse_vdc(i));
+}
+
+vec3 importance_sample_ggx(vec2 xi, vec3 n, float roughness)
+{
+	float a = roughness * roughness;
+	
+	float phi = 2.0 * PI * xi.x;
+	float cos_theta = sqrt((1.0 - xi.y) / (1.0 + (a * a - 1.0) * xi.y));
+	float sin_theta = sqrt(1.0 - cos_theta * cos_theta);
+	
+	vec3 h;
+	h.x = cos(phi) * sin_theta;
+	h.y = sin(phi) * sin_theta;
+	h.z = cos_theta;
+	
+	vec3 up = abs(n.z) < 0.999 ? vec3(0.0, 0.0, 1.0) : vec3(1.0, 0.0, 0.0);
+	vec3 tangent = normalize(cross(up, n));
+	vec3 bitangent = cross(n, tangent);
+	
+	vec3 samplevec = tangent * h.x + bitangent * h.y + n * h.z;
+	return normalize(samplevec);
+}
+
+void main(void)
+{
+	vec3 n = normalize(vert.position);
+	vec3 r = n;
+	vec3 v = r;
+
+	uint count = 1024u;
+	float total = 0.0;
+	vec3 prefiltered = vec3(0.0);
+	for (uint i = 0u; i < count; i++) {
+		vec2 xi = hammersley(i, count);
+		vec3 h = importance_sample_ggx(xi, n, roughness);
+		vec3 l = normalize(2.0 * dot(v, h) * h - v);
+		float ndotl = max(dot(n, l), 0.0);
+		if (ndotl > 0.0) {
+			float d = distribution_ggx(n, h, roughness);
+			float ndoth = max(dot(n, h), 0.0);
+			float hdotv = max(dot(h, v), 0.0); 
+			float pdf = d * ndoth / (4.0 * hdotv) + 0.0001;
+			float resolution = 512.0;
+			float sa_texel = 4.0 * PI / (6.0 * resolution * resolution);
+			float sa_sample = 1.0 / (float(count) * pdf + 0.0001);
+			float mip_level = roughness == 0.0 ? 0.0 : 0.5 * log2(sa_sample / sa_texel);
+			prefiltered += textureLod(cubemap, l, mip_level).rgb * ndotl;
+			total += ndotl;
+		}
+	}
+	prefiltered /= total;
+	frag_color = vec4(prefiltered, 1.0);
+}
diff --git a/pbr/ibl_specular/prefilter.vert b/pbr/ibl_specular/prefilter.vert
new file mode 100644
index 0000000..8f8862e
--- /dev/null
+++ b/pbr/ibl_specular/prefilter.vert
@@ -0,0 +1,17 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+
+out vert_t {
+	vec3 position;
+} vert;
+
+uniform mat4 projection;
+uniform mat4 view;
+
+void main(void)
+{
+	gl_Position = projection * view * vec4(position, 1.0);
+
+	vert.position = position;
+}
diff --git a/pbr/1.1.lighting/build.sh b/pbr/lighting/build.sh
index 2cd71b7..2cd71b7 100755
--- a/pbr/1.1.lighting/build.sh
+++ b/pbr/lighting/build.sh
diff --git a/pbr/1.1.lighting/default.frag b/pbr/lighting/default.frag
index 9351a1b..9351a1b 100644
--- a/pbr/1.1.lighting/default.frag
+++ b/pbr/lighting/default.frag
diff --git a/pbr/1.1.lighting/default.vert b/pbr/lighting/default.vert
index 1b953d7..1b953d7 100644
--- a/pbr/1.1.lighting/default.vert
+++ b/pbr/lighting/default.vert
diff --git a/pbr/2.1.2.ibl_irradiance/hdr.frag b/pbr/lighting/hdr.frag
index 01650ae..01650ae 100644
--- a/pbr/2.1.2.ibl_irradiance/hdr.frag
+++ b/pbr/lighting/hdr.frag
diff --git a/pbr/2.1.2.ibl_irradiance/hdr.vert b/pbr/lighting/hdr.vert
index 1b953d7..1b953d7 100644
--- a/pbr/2.1.2.ibl_irradiance/hdr.vert
+++ b/pbr/lighting/hdr.vert
diff --git a/pbr/1.1.lighting/lighting b/pbr/lighting/lighting
index a68bd2b..a68bd2b 100755
--- a/pbr/1.1.lighting/lighting
+++ b/pbr/lighting/lighting
diff --git a/pbr/1.1.lighting/lighting.c b/pbr/lighting/lighting.c
index d2a941d..d2a941d 100644
--- a/pbr/1.1.lighting/lighting.c
+++ b/pbr/lighting/lighting.c
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/pbr.frag b/pbr/lighting/pbr.frag
index db9edea..db9edea 100644
--- a/pbr/2.1.1.ibl_irradiance_conversion/pbr.frag
+++ b/pbr/lighting/pbr.frag
diff --git a/pbr/lighting/pbr.vert b/pbr/lighting/pbr.vert
new file mode 100644
index 0000000..e6e3800
--- /dev/null
+++ b/pbr/lighting/pbr.vert
@@ -0,0 +1,21 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+layout(location = 1) in vec3 normal;
+
+out vert_t {
+	vec3 position;
+	vec3 normal;
+} vert;
+
+uniform mat4 projection;
+uniform mat4 view;
+uniform mat4 model;
+
+void main(void)
+{
+	gl_Position = projection * view * model * vec4(position, 1.0);
+
+	vert.position = vec3(model * vec4(position, 1.0));
+	vert.normal = normalize(mat3(transpose(inverse(model))) * normal);
+}
diff --git a/pbr/1.2.textured/build.sh b/pbr/textured/build.sh
index 5c5427f..5c5427f 100755
--- a/pbr/1.2.textured/build.sh
+++ b/pbr/textured/build.sh
diff --git a/pbr/textured/hdr.frag b/pbr/textured/hdr.frag
new file mode 100644
index 0000000..01650ae
--- /dev/null
+++ b/pbr/textured/hdr.frag
@@ -0,0 +1,18 @@
+#version 330 core
+
+in vert_t {
+	vec2 tex_coords;
+} vert;
+
+out vec4 frag_color;
+
+uniform sampler2D colorbuffer;
+
+void main(void)
+{
+	const float gamma = 2.2;
+	vec3 color = vec3(texture(colorbuffer, vert.tex_coords));
+	color /= color + vec3(1.0);
+	color = pow(color, vec3(1.0 / gamma));
+	frag_color = vec4(color, 1.0);
+}
diff --git a/pbr/textured/hdr.vert b/pbr/textured/hdr.vert
new file mode 100644
index 0000000..1b953d7
--- /dev/null
+++ b/pbr/textured/hdr.vert
@@ -0,0 +1,17 @@
+#version 330 core
+
+layout(location = 0) in vec3 position;
+layout(location = 2) in vec2 tex_coords;
+
+out vert_t {
+	vec2 tex_coords;
+} vert;
+
+uniform mat4 model;
+
+void main(void)
+{
+	gl_Position = model * vec4(position, 1.0);
+
+	vert.tex_coords = tex_coords;
+}
diff --git a/pbr/1.2.textured/pbr.frag b/pbr/textured/pbr.frag
index f0aaeca..f0aaeca 100644
--- a/pbr/1.2.textured/pbr.frag
+++ b/pbr/textured/pbr.frag
diff --git a/pbr/1.2.textured/pbr.vert b/pbr/textured/pbr.vert
index 0ff1bdb..0ff1bdb 100644
--- a/pbr/1.2.textured/pbr.vert
+++ b/pbr/textured/pbr.vert
diff --git a/pbr/1.2.textured/textured b/pbr/textured/textured
index e339406..e339406 100755
--- a/pbr/1.2.textured/textured
+++ b/pbr/textured/textured
diff --git a/pbr/1.2.textured/textured.c b/pbr/textured/textured.c
index e8ed096..e8ed096 100644
--- a/pbr/1.2.textured/textured.c
+++ b/pbr/textured/textured.c