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#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <ft2build.h>
#include FT_FREETYPE_H
#include "common.h"
typedef struct {
U32 texture_id;
V2F size;
V2F bearing;
U32 advance;
} char_t;
char_t chars[128];
static U32 vao, vbo;
V2F get_text_size(const char *text, F32 scale)
{
V2F size = {0};
for (const char *c = text; *c; c++) {
char_t ch = chars[(U8)*c];
F32 h = ch.size.y * scale;
if (h > size.y)
size.y = h;
size.x += (ch.advance >> 6) * scale;
}
return size;
}
void render_text(const char *text, U32 shader, V2F pos, F32 scale, V3F color)
{
glUseProgram(shader);
shader_set_3fv(shader, "text_color", color);
glActiveTexture(GL_TEXTURE0);
glBindVertexArray(vao);
for (const char *c = text; *c; c++) {
char_t ch = chars[(U8)*c];
F32 x = pos.x + ch.bearing.x * scale;
F32 y = pos.y - (ch.size.y - ch.bearing.y) * scale;
F32 w = ch.size.x * scale;
F32 h = ch.size.y * scale;
F32 vertices[] = {
x, y + h, 0.0f, 0.0f,
x, y, 0.0f, 1.0f,
x + w, y, 1.0f, 1.0f,
x, y + h, 0.0f, 0.0f,
x + w, y, 1.0f, 1.0f,
x + w, y + h, 1.0f, 0.0f,
};
glBindTexture(GL_TEXTURE_2D, ch.texture_id);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindTexture(GL_TEXTURE_2D, 0);
pos.x += (ch.advance >> 6) * scale;
}
glBindVertexArray(0);
glUseProgram(0);
}
void render_bounds(const char *text, U32 shader, V2F pos, F32 scale)
{
glUseProgram(shader);
glBindVertexArray(vao);
V2F size = get_text_size(text, scale);
F32 x = pos.x;
F32 y = pos.y;
F32 w = size.x;
F32 h = size.y;
F32 vertices[] = {
x, y + h, 0.0f, 0.0f,
x, y, 0.0f, 1.0f,
x + w, y, 1.0f, 1.0f,
x, y + h, 0.0f, 0.0f,
x + w, y, 1.0f, 1.0f,
x + w, y + h, 1.0f, 0.0f,
};
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
glDrawArrays(GL_TRIANGLES, 0, 6);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glBindVertexArray(0);
glUseProgram(0);
}
int main(void)
{
state_t state = init_state(1600, 800, 1);
init_glfw(&state);
init_gl();
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
FT_Library ft;
if (FT_Init_FreeType(&ft))
die("failed to initialize freetype");
FT_Face face;
const char *font_name = "ibmvga8x16.ttf";
if (FT_New_Face(ft, font_name, 0, &face))
die("failed to load %s", font_name);
FT_Set_Pixel_Sizes(face, 0, 48);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
for (U32 c = 0; c < 128; c++) {
if (FT_Load_Char(face, c, FT_LOAD_RENDER))
die("failed to load X character");
U32 texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED,
face->glyph->bitmap.width,
face->glyph->bitmap.rows,
0, GL_RED, GL_UNSIGNED_BYTE,
face->glyph->bitmap.buffer);
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_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
chars[c] = (char_t){
texture,
{face->glyph->bitmap.width, face->glyph->bitmap.rows},
{face->glyph->bitmap_left, face->glyph->bitmap_top},
face->glyph->advance.x
};
}
FT_Done_Face(face);
FT_Done_FreeType(ft);
U32 shader = add_shader("glyph.vert", "glyph.frag", 0);
MAT4 projection = ortho(0.0f, state.width, 0.0f, state.height, 0.0f, 1.0f);
glUseProgram(shader);
shader_set_mat4fv(shader, "projection", projection);
glUseProgram(0);
U32 bounds_shader = add_shader("bounds.vert", "bounds.frag", 0);
glUseProgram(bounds_shader);
shader_set_mat4fv(bounds_shader, "projection", projection);
glUseProgram(0);
glGenVertexArrays(1, &vao);
glGenBuffers(1, &vbo);
glBindVertexArray(vao);
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, sizeof(F32) * 6 * 4, 0, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(F32), 0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
glClearColor(0.16f, 0.16f, 0.16f, 1.0f);
F32 time = 0.0f;
V2F pos = {state.width / 2.0f, state.height / 2.0f};
V2F vel = {0.5f, 0.5f};
S32 show_bounds = 0;
const char *text = "foo, bar, nope";
F32 scale = 1.0f;
V2F size = get_text_size(text, scale);
while (!glfwWindowShouldClose(state.window)) {
handle_glfw_events(state.window, &state.input);
F32 dt = lock_framerate(60);
/* update */
F32 sin_value = 0.25f * sinf(time) + 0.75f;
F32 cos_value = 0.25f * cosf(time) + 0.75f;
V3F color = v3f(sin_value, cos_value, sin_value);
F32 speed = 256.0f;
V2F new_pos = v2f_add(pos, v2f_scalef(vel, speed * dt));
if (new_pos.x < 0.0f || new_pos.x + size.x > state.width)
vel.x = -vel.x;
if (new_pos.y < 0.0f || new_pos.y + size.y > state.height)
vel.y = -vel.y;
pos = new_pos;
if (key_first_press(state.input.jump))
show_bounds = !show_bounds;
time += dt;
/* render */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
render_text(text, shader, pos, scale, color);
if (show_bounds)
render_bounds(text, bounds_shader, pos, scale);
glfwSwapBuffers(state.window);
}
return 0;
}
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