127 lines
4.1 KiB
C
127 lines
4.1 KiB
C
#include <std/font_provider.h>
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#define STBTT_STATIC
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#define STB_TRUETYPE_IMPLEMENTATION
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#pragma clang diagnostic push
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#pragma clang diagnostic ignored "-Wunused-function"
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#include <stb_truetype.h>
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#pragma clang diagnostic pop
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TextureAtlas font_texture_atlas_create(Arena* arena, Renderer* renderer, TextureAtlasCreate create)
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{
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auto font_file = file_read(arena, create.font_path);
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stbtt_fontinfo font_info;
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if (!stbtt_InitFont(&font_info, font_file.pointer, stbtt_GetFontOffsetForIndex(font_file.pointer, 0)))
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{
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failed_execution();
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}
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TextureAtlas result = {};
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u32 character_count = 256;
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result.characters = arena_allocate(arena, FontCharacter, character_count);
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result.kerning_tables = arena_allocate(arena, s32, character_count * character_count);
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result.height = (u32)sqrtf((f32)(create.text_height * create.text_height * character_count));
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result.width = result.height;
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result.pointer = arena_allocate(arena, u32, result.width * result.height);
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auto scale_factor = stbtt_ScaleForPixelHeight(&font_info, create.text_height);
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int ascent;
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int descent;
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int line_gap;
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stbtt_GetFontVMetrics(&font_info, &ascent, &descent, &line_gap);
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result.ascent = (u32)roundf(ascent * scale_factor);
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result.descent = (u32)roundf(descent * scale_factor);
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result.line_gap = (u32)roundf(line_gap * scale_factor);
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u32 x = 0;
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u32 y = 0;
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u32 max_row_height = 0;
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u32 first_character = ' ';
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u32 last_character = '~';
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for (auto i = first_character; i <= last_character; ++i)
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{
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u32 width;
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u32 height;
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int advance;
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int left_bearing;
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auto ch = (u8)i;
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auto* character = &result.characters[i];
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stbtt_GetCodepointHMetrics(&font_info, ch, &advance, &left_bearing);
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character->advance = (u32)roundf(advance * scale_factor);
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character->left_bearing = (u32)roundf(left_bearing * scale_factor);
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u8* bitmap = stbtt_GetCodepointBitmap(&font_info, 0.0f, scale_factor, ch, (int*)&width, (int*)&height, &character->x_offset, &character->y_offset);
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auto* kerning_table = result.kerning_tables + i * character_count;
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for (u32 j = first_character; j <= last_character; j += 1)
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{
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auto kerning_advance = stbtt_GetCodepointKernAdvance(&font_info, i, j);
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kerning_table[j] = (s32)roundf(kerning_advance * scale_factor);
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}
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if (x + width > result.width)
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{
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y += max_row_height;
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max_row_height = height;
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x = 0;
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}
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else
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{
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max_row_height = MAX(height, max_row_height);
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}
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character->x = x;
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character->y = y;
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character->width = width;
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character->height = height;
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auto* source = bitmap;
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auto* destination = result.pointer;
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for (u32 bitmap_y = 0; bitmap_y < height; bitmap_y += 1)
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{
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for (u32 bitmap_x = 0; bitmap_x < width; bitmap_x += 1)
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{
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auto source_index = bitmap_y * width + bitmap_x;
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auto destination_index = (bitmap_y + y) * result.width + (bitmap_x + x);
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auto value = source[source_index];
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destination[destination_index] = ((u32)value << 24) | 0xffffff;
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}
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}
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x += width;
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stbtt_FreeBitmap(bitmap, 0);
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}
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result.texture = renderer_texture_create(renderer, (TextureMemory) {
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.pointer = result.pointer,
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.width = result.width,
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.height = result.height,
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.depth = 1,
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.format = TEXTURE_FORMAT_R8G8B8A8_SRGB,
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});
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return result;
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}
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U32Vec2 texture_atlas_compute_string_rect(String string, const TextureAtlas* atlas)
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{
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auto height = atlas->ascent - atlas->descent;
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u32 x_offset = 0;
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u32 y_offset = height;
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for (u64 i = 0; i < string.length; i += 1)
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{
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auto ch = string.pointer[i];
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auto* character = &atlas->characters[ch];
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auto kerning = (atlas->kerning_tables + ch * 256)[string.pointer[i + 1]];
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x_offset += character->advance + kerning;
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}
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return (U32Vec2) { .x = x_offset, .y = y_offset };
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}
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