diff options
Diffstat (limited to 'text.cpp')
| -rw-r--r-- | text.cpp | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/text.cpp b/text.cpp new file mode 100644 index 0000000..c3c3de4 --- /dev/null +++ b/text.cpp @@ -0,0 +1,172 @@ +// 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, float clip_left) { + 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; + // stb_truetype uses a pixel-based top-is-y=0 coordinate system, so we need to convert back and forth + float resolution = (float)state->win_height; + float inv_resolution = 1 / resolution; + + + x *= resolution; + y = 1 - y; + y *= resolution; + + 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 *= inv_resolution; + q.y0 *= inv_resolution; + q.x1 *= inv_resolution; + q.y1 *= inv_resolution; + q.y0 = 1 - q.y0; + q.y1 = 1 - q.y1; +#if 1 + if (q.x1 < clip_left) { + // entirety of character is to the left of clip_left. + } else if (q.x0 < clip_left) { + // part of character is to the left of clip_left + float char_width = q.x1 - q.x0; // full width of character + float display_char_width = q.x1 - clip_left; // width of character which is being rendered, after clipping + float char_fraction = display_char_width / char_width; // fraction of character rendered + float s0 = q.s1 - char_fraction * (q.s1 - q.s0); // calculate where to start from + float x0 = clip_left; + glTexCoord2f( s0, q.t0); glVertex2f( x0, q.y0); + glTexCoord2f(q.s1, q.t0); glVertex2f(q.x1, q.y0); + glTexCoord2f(q.s1, q.t1); glVertex2f(q.x1, q.y1); + glTexCoord2f( s0, q.t1); glVertex2f( x0, q.y1); + } else +#endif + { + // 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_resolution; + *yp = 1 - y * inv_resolution; +} + +static void text_render2f(State *state, Font *font, char const *s, float x, float y) { + text_render_(state, font, s, &x, &y, true, 0); +} +static void text_render(State *state, Font *font, char const *s, v2 pos) { + text_render_(state, font, s, &pos.x, &pos.y, true, 0); +} + +static float text_font_char_height(Font *font) { + return font->char_height * 0.666667f; +} + +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, 0); + return V2(x, y + text_font_char_height(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); +} |