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Alessandro Mauri 2023-02-12 09:34:44 +01:00
parent a32b211d20
commit 5018ccbbb0
13 changed files with 5549 additions and 0 deletions
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text_rendering/font.c Normal file
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#define _POSIX_C_SOURCE 200809l
#define STB_TRUETYPE_IMPLEMENTATION
#define STBTT_STATIC
#include <grapheme.h>
#include "stb_truetype.h"
#include "util.h"
#include "font.h"
#define UTF8(c) (c&0x80)
// Generates a cached atlas of font glyphs encoded usign a signed distance field
// https://www.youtube.com/watch?v=1b5hIMqz_wM
// https://github.com/pjako/msdf_c
// this way the texture atlas for the font will be bigger but we save up the space
// needed for rendering the font in multiple sizes
struct font_atlas {
unsigned int glyphs, width, height;
unsigned char *atlas;
unsigned int glyph_max_w, glyph_max_h;
struct {
stbtt_fontinfo info;
float scale;
} stb;
int file_size;
unsigned char *file;
};
// loads a font into memory, storing all the ASCII characters in the atlas
int load_font(struct font_atlas *atlas, const char *path, int height)
{
if (!atlas || !path)
return -1;
dump_file(path, &(atlas->file), &(atlas->file_size));
stbtt_InitFont(&(atlas->stb.info), atlas->file, 0);
atlas->stb.scale = stbtt_ScaleForPixelHeight(&(atlas->stb.info), height);
int ascent, descent, linegap, baseline;
int x0,y0,x1,y1;
stbtt_GetFontVMetrics(&(atlas->stb.info), &ascent, &descent, &linegap);
stbtt_GetFontBoundingBox(&(atlas->stb.info), &x0, &y0, &x1, &y1);
baseline = atlas->stb.scale * -y0;
atlas->glyph_max_w = (atlas->stb.scale*x1) - (atlas->stb.scale*x0);
atlas->glyph_max_h = (baseline+atlas->stb.scale*y1) - (baseline+atlas->stb.scale*y0);
atlas->atlas = emalloc(atlas->glyph_max_w*atlas->glyph_max_h*CACHE_SIZE);
return 0;
}
int free_font(struct font_atlas *atlas)
{
efree(atlas->atlas);
efree(atlas->file);
return 0;
}