1 files changed, 25 insertions, 0 deletions
diff --git a/pbr/2.1.1.ibl_irradiance_conversion/cubemap.frag b/pbr/2.1.1.ibl_irradiance_conversion/cubemap.frag
new file mode 100644
index 0000000..349347a
--- /dev/null
+++ b/pbr/2.1.1.ibl_irradiance_conversion/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);
+}