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// returns:
// 1 on success
// 0 on failure (bitmap too small)
// -1 on error
static int text_font_load_(State *state, Font *font, u8 const *data,
float char_height, int bitmap_width, int bitmap_height) {
u32 mark = tmp_push(state);
u8 *bitmap = tmp_alloc(state, (size_t)bitmap_width * (size_t)bitmap_height);
int ret = 1;
/*
The number of bytes in a row of a texture must be a multiple of 4.
See: https://www.khronos.org/opengl/wiki/Common_Mistakes#Texture_upload_and_pixel_reads
*/
assert(bitmap_width % 4 == 0);
font->char_height = char_height;
font->tex_width = bitmap_width;
font->tex_height = bitmap_height;
if (bitmap) {
int err;
err = stbtt_BakeFontBitmap(data, 0, char_height, bitmap, bitmap_width, bitmap_height, 32, arr_count(font->char_data),
font->char_data);
if (err > 0) {
GLuint texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, bitmap_width, bitmap_height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, bitmap);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
font->texture = texture;
debug_println("Loaded font (size = %f), using %d rows of a %dx%d bitmap.",
char_height, err, bitmap_width, bitmap_height);
} else {
// bitmap not big enough
ret = 0;
}
} else {
debug_println("Not enough memory for font bitmap.");
ret = -1;
}
tmp_pop(state, mark);
return ret;
}
static bool text_font_load(State *state, Font *font, char const *filename, float char_height) {
bool success = false;
FILE *fp = fopen(filename, "rb");
if (fp) {
fseek(fp, 0, SEEK_END);
size_t file_size = (size_t)ftell(fp);
fseek(fp, 0, SEEK_SET);
u8 *data = (u8 *)calloc(1, file_size);
if (data) {
fread(data, 1, file_size, fp);
int bitmap_width = 400, bitmap_height = 400;
while (bitmap_width < 2000) {
int r = text_font_load_(state, font, data, char_height, bitmap_width, bitmap_height);
if (r == -1) {
break;
} else if (r == 1) {
success = true;
break;
}
bitmap_width *= 2;
bitmap_height *= 2;
}
free(data);
} else {
debug_println("Out of memory.");
}
fclose(fp);
} else {
debug_println("File not found: %s.", filename);
}
if (!success) {
memset(font, 0, sizeof *font);
}
return success;
}
static void text_render_(State *state, Font *font, char const *s, float *xp, float *yp, bool render) {
if (!font->char_height) return; // font not loaded properly
stbtt_bakedchar *cdata = font->char_data;
int tex_w = font->tex_width, tex_h = font->tex_height;
float x = *xp, y = *yp;
float widthf = (float)state->win_width, heightf = (float)state->win_height;
float inv_widthf = 1.0f / widthf, inv_heightf = 1.0f / heightf;
// convert between GL and stb_truetype coordinates
x = (x + 1) * 0.5f * widthf;
y = (1 - (y + 1) * 0.5f) * heightf;
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, font->texture);
glBegin(GL_QUADS);
for (; *s; ++s) {
char c = *s;
if (c >= 32 && (size_t)c < 32+arr_count(font->char_data)) {
stbtt_aligned_quad q = {};
stbtt_GetBakedQuad(cdata, tex_w, tex_h, c - 32, &x, &y, &q, 1);
if (render) {
q.x0 = (q.x0 * inv_widthf) * 2 - 1;
q.x1 = (q.x1 * inv_widthf) * 2 - 1;
q.y0 = (1 - q.y0 * inv_heightf) * 2 - 1;
q.y1 = (1 - q.y1 * inv_heightf) * 2 - 1;
{
// no clipping
#if 0
printf("%f %f %f %f\n",q.s0*tex_w,q.t0*tex_h,q.s1*tex_w,q.t1*tex_h);
#endif
glTexCoord2f(q.s0, q.t0); glVertex2f(q.x0, q.y0);
glTexCoord2f(q.s1, q.t0); glVertex2f(q.x1, q.y0);
glTexCoord2f(q.s1, q.t1); glVertex2f(q.x1, q.y1);
glTexCoord2f(q.s0, q.t1); glVertex2f(q.x0, q.y1);
}
}
}
}
glEnd();
glDisable(GL_TEXTURE_2D);
*xp = (x * inv_widthf) * 2 - 1;
*yp = (1 - y * inv_heightf) * 2 - 1;
}
static void text_render2f(State *state, Font *font, char const *s, float x, float y) {
text_render_(state, font, s, &x, &y, true);
}
static void text_render(State *state, Font *font, char const *s, v2 pos) {
text_render_(state, font, s, &pos.x, &pos.y, true);
}
static float text_font_char_height(State *state, Font *font) {
return font->char_height / (float)state->win_width * 1.3333333f;
}
static v2 text_get_size(State *state, Font *font, char const *s) {
float x = 0, y = 0;
text_render_(state, font, s, &x, &y, false);
return V2(x, y + text_font_char_height(state, font));
}
static void text_render_centered(State *state, Font *font, char const *s, v2 center) {
text_render(state, font, s, v2_sub(center, v2_scale(text_get_size(state, font, s), 0.5f)));
}
static void text_font_free(Font *font) {
glDeleteTextures(1, &font->texture);
}
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