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Improve the performance of text rendering #53

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212ba7c
Create a cache around `fontCalcGlyphPos` for ASCII characters
TheGag96 Mar 8, 2026
116f09e
Improve text rendering performance again by treating font sheets as c…
TheGag96 Mar 8, 2026
52f0cbc
fixup! Create a cache around `fontCalcGlyphPos` for ASCII characters
TheGag96 Mar 9, 2026
716c205
Funnel system font handling into the same codepaths as user fonts, ap…
TheGag96 Mar 10, 2026
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10 changes: 10 additions & 0 deletions include/c2d/font.h
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,16 @@ charWidthInfo_s* C2D_FontGetCharWidthInfo(C2D_Font font, int glyphIndex);
*/
void C2D_FontCalcGlyphPos(C2D_Font font, fontGlyphPos_s* out, int glyphIndex, u32 flags, float scaleX, float scaleY);

/** @brief Calculate glyph position of a given Unicode codepoint. Uses a cached value when the codepoint is ASCII, flags are 0, and scales are 1.
* @param[in] font Font to read from, or NULL for system font
* @param[out] out Glyph position
* @param[in] codepoint The Unicode codepoint of the glyph
* @param[in] flags Misc flags
* @param[in] scaleX Size to scale in X
* @param[in] scaleY Size to scale in Y
*/
void C2D_FontCalcGlyphPosFromCodePoint(C2D_Font font, fontGlyphPos_s* out, u32 codepoint, u32 flags, float scaleX, float scaleY);

/** @brief Get the font info structure associated with the font
* @param[in] font Font to read from, or NULL for the system font
* @returns FINF associated with the font
Expand Down
128 changes: 96 additions & 32 deletions source/font.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
#include "internal.h"
#include <c2d/font.h>

C2D_Font_s g_systemFont;

C2D_Font C2D_FontLoad(const char* filename)
{
FILE* f = fopen(filename, "rb");
Expand All @@ -18,38 +20,72 @@ static inline C2D_Font C2Di_FontAlloc(void)
return (C2D_Font)malloc(sizeof(struct C2D_Font_s));
}

static void fillSheet(C3D_Tex *tex, void *data, TGLP_s *glyphInfo)
{
tex->data = data;
tex->fmt = glyphInfo->sheetFmt;
tex->size = glyphInfo->sheetSize;
tex->width = glyphInfo->sheetWidth;
tex->height = glyphInfo->sheetHeight;
tex->param = GPU_TEXTURE_MAG_FILTER(GPU_LINEAR) | GPU_TEXTURE_MIN_FILTER(GPU_LINEAR)
| GPU_TEXTURE_WRAP_S(GPU_CLAMP_TO_EDGE) | GPU_TEXTURE_WRAP_T(GPU_CLAMP_TO_EDGE);
tex->border = 0;
tex->lodParam = 0;
}

static C2D_Font C2Di_PostLoadFont(C2D_Font font)
{
if (!font->cfnt)
{
free(font);
font = NULL;
} else
}
else
{
fontFixPointers(font->cfnt);
if (font->cfnt != fontGetSystemFont())
{
fontFixPointers(font->cfnt);
}

TGLP_s* glyphInfo = font->cfnt->finf.tglp;
font->glyphSheets = malloc(sizeof(C3D_Tex)*glyphInfo->nSheets);
font->textScale = 30.0f / glyphInfo->cellHeight;

// The way TGLP_s is set up, all of a font's texture sheets are adjacent in memory and have the same size. We can
// reinterpet the memory to describe a smaller set of much taller textures if we'd like. If we choose the right size,
// we can get all of the ASCII glyphs under a single texture, which will massively improve performance by reducing
// texture swaps within a piece of all-English text down to 0! We don't need any extra linear allocating to do this!
// Let's combine as many sheets as it takes to get to a big sheet height of 1024, which is the maximum height a
// texture can have.
font->sheetsPerBigSheet = 1024U / glyphInfo->sheetHeight;
u32 numSheetsBig = glyphInfo->nSheets / font->sheetsPerBigSheet;
u32 numSheetsSmall = glyphInfo->nSheets % font->sheetsPerBigSheet;
u32 numSheetsTotal = numSheetsBig + numSheetsSmall;
font->numSheetsCombined = glyphInfo->nSheets - numSheetsSmall;

font->glyphSheets = malloc(sizeof(C3D_Tex)*numSheetsTotal);
if (!font->glyphSheets)
{
C2D_FontFree(font);
return NULL;
}

int i;
for (i = 0; i < glyphInfo->nSheets; i++)
memset(font->glyphSheets, 0, sizeof(sizeof(C3D_Tex)*numSheetsTotal));
for (u32 i = 0; i < numSheetsBig; i++)
{
C3D_Tex* tex = &font->glyphSheets[i];
tex->data = &glyphInfo->sheetData[glyphInfo->sheetSize*i];
tex->fmt = glyphInfo->sheetFmt;
tex->size = glyphInfo->sheetSize;
tex->width = glyphInfo->sheetWidth;
tex->height = glyphInfo->sheetHeight;
tex->param = GPU_TEXTURE_MAG_FILTER(GPU_LINEAR) | GPU_TEXTURE_MIN_FILTER(GPU_LINEAR)
| GPU_TEXTURE_WRAP_S(GPU_CLAMP_TO_BORDER) | GPU_TEXTURE_WRAP_T(GPU_CLAMP_TO_BORDER);
tex->border = 0;
tex->lodParam = 0;
fillSheet(tex, fontGetGlyphSheetTex(font->cfnt, i * font->sheetsPerBigSheet), glyphInfo);
tex->height = (uint16_t) (tex->height * font->sheetsPerBigSheet);
tex->size = tex->size * font->sheetsPerBigSheet;
}

for (u32 i = 0; i < numSheetsSmall; i++)
{
fillSheet(&font->glyphSheets[numSheetsBig + i], fontGetGlyphSheetTex(font->cfnt, numSheetsBig * font->sheetsPerBigSheet + i), glyphInfo);
}

for (u32 i = 0; i < NUM_ASCII_CHARACTERS; i++)
{
// This will readjust glyph UVs to account for being a part of the combined texture.
C2D_FontCalcGlyphPos(NULL, &font->asciiCache[i], fontGlyphIndexFromCodePoint(font->cfnt, i), 0, 1.0, 1.0);
}
}
return font;
Expand Down Expand Up @@ -151,6 +187,13 @@ static C2D_Font C2Di_FontLoadFromArchive(u64 tid, const char* path)
return C2Di_PostLoadFont(font);
}

C2D_Font C2Di_LoadSystemFont(void)
{
g_systemFont.cfnt = fontGetSystemFont();
C2Di_PostLoadFont(&g_systemFont);
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@R-YaTian R-YaTian May 8, 2026

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The indentation style is inconsistent here.

return &g_systemFont;
}

static unsigned C2Di_RegionToFontIndex(CFG_Region region)
{
switch (region)
Expand Down Expand Up @@ -196,7 +239,7 @@ C2D_Font C2D_FontLoadSystem(CFG_Region region)

void C2D_FontFree(C2D_Font font)
{
if (font)
if (font && font != &g_systemFont)
{
if (font->cfnt)
linearFree(font->cfnt);
Expand All @@ -206,7 +249,7 @@ void C2D_FontFree(C2D_Font font)

void C2D_FontSetFilter(C2D_Font font, GPU_TEXTURE_FILTER_PARAM magFilter, GPU_TEXTURE_FILTER_PARAM minFilter)
{
if (!font)
if (!font || font == &g_systemFont)
return;

TGLP_s* glyphInfo = font->cfnt->finf.tglp;
Expand All @@ -221,32 +264,53 @@ void C2D_FontSetFilter(C2D_Font font, GPU_TEXTURE_FILTER_PARAM magFilter, GPU_TE

int C2D_FontGlyphIndexFromCodePoint(C2D_Font font, u32 codepoint)
{
if (!font)
return fontGlyphIndexFromCodePoint(fontGetSystemFont(), codepoint);
else
return fontGlyphIndexFromCodePoint(font->cfnt, codepoint);
if (!font) font = &g_systemFont;
return fontGlyphIndexFromCodePoint(font->cfnt, codepoint);
}

charWidthInfo_s* C2D_FontGetCharWidthInfo(C2D_Font font, int glyphIndex)
{
if (!font)
return fontGetCharWidthInfo(fontGetSystemFont(), glyphIndex);
else
return fontGetCharWidthInfo(font->cfnt, glyphIndex);
if (!font) font = &g_systemFont;
return fontGetCharWidthInfo(font->cfnt, glyphIndex);
}

void C2D_FontCalcGlyphPos(C2D_Font font, fontGlyphPos_s* out, int glyphIndex, u32 flags, float scaleX, float scaleY)
{
if (!font)
fontCalcGlyphPos(out, fontGetSystemFont(), glyphIndex, flags, scaleX, scaleY);
if (!font) font = &g_systemFont;
fontCalcGlyphPos(out, font->cfnt, glyphIndex, flags, scaleX, scaleY);

if (out->sheetIndex < font->numSheetsCombined)
{
u32 indexWithinBigSheet = out->sheetIndex % font->sheetsPerBigSheet;
out->sheetIndex /= font->sheetsPerBigSheet;

// Readjust glyph UVs to account for being a part of the combined texture.
out->texcoord.top = (out->texcoord.top + (font->sheetsPerBigSheet - indexWithinBigSheet - 1)) / (float) font->sheetsPerBigSheet;
out->texcoord.bottom = (out->texcoord.bottom + (font->sheetsPerBigSheet - indexWithinBigSheet - 1)) / (float) font->sheetsPerBigSheet;
}
else
{
out->sheetIndex = out->sheetIndex - font->numSheetsCombined + font->numSheetsCombined / font->sheetsPerBigSheet;
}
}

void C2D_FontCalcGlyphPosFromCodePoint(C2D_Font font, fontGlyphPos_s* out, u32 codepoint, u32 flags, float scaleX, float scaleY)
{
if (!font) font = &g_systemFont;

// Building glyph positions is pretty expensive, but we could just store the results for plain ASCII.
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@R-YaTian R-YaTian May 8, 2026

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The indentation style is inconsistent.

if (codepoint < NUM_ASCII_CHARACTERS && flags == 0 && scaleX == 1 && scaleY == 1)
{
*out = font->asciiCache[codepoint];
}
else
fontCalcGlyphPos(out, font->cfnt, glyphIndex, flags, scaleX, scaleY);
{
C2D_FontCalcGlyphPos(font, out, C2D_FontGlyphIndexFromCodePoint(font, codepoint), 0, 1.0f, 1.0f);
}
}

FINF_s* C2D_FontGetInfo(C2D_Font font)
{
if (!font)
return fontGetInfo(NULL);
else
return fontGetInfo(font->cfnt);
if (!font) font = &g_systemFont;
return fontGetInfo(font->cfnt);
}
13 changes: 11 additions & 2 deletions source/internal.h
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
#pragma once
#include <c2d/base.h>
#include <c2d/font.h>
#include <3ds/font.h>

typedef struct
{
Expand Down Expand Up @@ -72,12 +74,16 @@ enum
C2DiF_DirtyAny = C2DiF_DirtyProj | C2DiF_DirtyMdlv | C2DiF_DirtyTex | C2DiF_DirtyMode | C2DiF_DirtyFade,
};

struct C2D_Font_s
#define NUM_ASCII_CHARACTERS 128
typedef struct C2D_Font_s
{
CFNT_s* cfnt;
C3D_Tex* glyphSheets;
float textScale;
};
u32 numSheetsCombined;
u32 sheetsPerBigSheet;
fontGlyphPos_s asciiCache[NUM_ASCII_CHARACTERS];
} C2D_Font_s;

static inline C2Di_Context* C2Di_GetContext(void)
{
Expand Down Expand Up @@ -117,3 +123,6 @@ void C2Di_AppendQuad(void);
void C2Di_AppendVtx(float x, float y, float z, float u, float v, float ptx, float pty, u32 color);
void C2Di_FlushVtxBuf(void);
void C2Di_Update(void);

extern C2D_Font_s g_systemFont;
C2D_Font C2Di_LoadSystemFont(void);
70 changes: 17 additions & 53 deletions source/text.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,9 +4,6 @@
#include <stdlib.h>
#include <stdarg.h>

static C3D_Tex* s_glyphSheets;
static float s_textScale;

typedef struct C2Di_Glyph_s
{
u32 lineNo;
Expand Down Expand Up @@ -60,35 +57,15 @@ static int C2Di_GlyphComp(const void* _g1, const void* _g2)
static void C2Di_TextEnsureLoad(void)
{
// Skip if already loaded
if (s_glyphSheets)
if (g_systemFont.glyphSheets)
return;

// Ensure the shared system font is mapped
if (R_FAILED(fontEnsureMapped()))
svcBreak(USERBREAK_PANIC);

// Load the glyph texture sheets
CFNT_s* font = fontGetSystemFont();
TGLP_s* glyphInfo = fontGetGlyphInfo(font);
s_glyphSheets = malloc(sizeof(C3D_Tex)*glyphInfo->nSheets);
s_textScale = 30.0f / glyphInfo->cellHeight;
if (!s_glyphSheets)
if (!C2Di_LoadSystemFont())
svcBreak(USERBREAK_PANIC);

int i;
for (i = 0; i < glyphInfo->nSheets; i ++)
{
C3D_Tex* tex = &s_glyphSheets[i];
tex->data = fontGetGlyphSheetTex(font, i);
tex->fmt = glyphInfo->sheetFmt;
tex->size = glyphInfo->sheetSize;
tex->width = glyphInfo->sheetWidth;
tex->height = glyphInfo->sheetHeight;
tex->param = GPU_TEXTURE_MAG_FILTER(GPU_LINEAR) | GPU_TEXTURE_MIN_FILTER(GPU_LINEAR)
| GPU_TEXTURE_WRAP_S(GPU_CLAMP_TO_BORDER) | GPU_TEXTURE_WRAP_T(GPU_CLAMP_TO_BORDER);
tex->border = 0;
tex->lodParam = 0;
}
}

C2D_TextBuf C2D_TextBufNew(size_t maxGlyphs)
Expand Down Expand Up @@ -139,6 +116,8 @@ const char* C2D_TextParseLine(C2D_Text* text, C2D_TextBuf buf, const char* str,

const char* C2D_TextFontParseLine(C2D_Text* text, C2D_Font font, C2D_TextBuf buf, const char* str, u32 lineNo)
{
if (!font) font = &g_systemFont;

const uint8_t* p = (const uint8_t*)str;
text->font = font;
text->buf = buf;
Expand All @@ -161,14 +140,11 @@ const char* C2D_TextFontParseLine(C2D_Text* text, C2D_Font font, C2D_TextBuf buf
p += units;

fontGlyphPos_s glyphData;
C2D_FontCalcGlyphPos(font, &glyphData, C2D_FontGlyphIndexFromCodePoint(font, code), 0, 1.0f, 1.0f);
C2D_FontCalcGlyphPosFromCodePoint(font, &glyphData, code, 0, 1.0f, 1.0f);
if (glyphData.width > 0.0f)
{
C2Di_Glyph* glyph = &buf->glyphs[buf->glyphCount++];
if (font)
glyph->sheet = &font->glyphSheets[glyphData.sheetIndex];
else
glyph->sheet = &s_glyphSheets[glyphData.sheetIndex];
glyph->sheet = &font->glyphSheets[glyphData.sheetIndex];
glyph->xPos = text->width + glyphData.xOffset;
glyph->lineNo = lineNo;
glyph->wordNo = wordNum;
Expand All @@ -192,7 +168,7 @@ const char* C2D_TextFontParseLine(C2D_Text* text, C2D_Font font, C2D_TextBuf buf
wordNum++;

text->end = buf->glyphCount;
text->width *= font ? font->textScale : s_textScale;
text->width *= font->textScale;
text->lines = 1;
text->words = wordNum;
return (const char*)p;
Expand All @@ -205,6 +181,8 @@ const char* C2D_TextParse(C2D_Text* text, C2D_TextBuf buf, const char* str)

const char* C2D_TextFontParse(C2D_Text* text, C2D_Font font, C2D_TextBuf buf, const char* str)
{
if (!font) font = &g_systemFont;

text->font = font;
text->buf = buf;
text->begin = buf->glyphCount;
Expand Down Expand Up @@ -240,10 +218,8 @@ void C2D_TextGetDimensions(const C2D_Text* text, float scaleX, float scaleY, flo
*outWidth = scaleX*text->width;
if (outHeight)
{
if (text->font)
*outHeight = ceilf(scaleY*text->font->textScale*text->font->cfnt->finf.lineFeed)*text->lines;
else
*outHeight = ceilf(scaleY*s_textScale*fontGetInfo(fontGetSystemFont())->lineFeed)*text->lines;
C2D_Font font = text->font ? text->font : &g_systemFont;
*outHeight = ceilf(scaleY*font->textScale*font->cfnt->finf.lineFeed)*text->lines;
}
}

Expand Down Expand Up @@ -321,24 +297,15 @@ void C2D_DrawText(const C2D_Text* text, u32 flags, float x, float y, float z, fl
C2Di_Glyph* begin = &text->buf->glyphs[text->begin];
C2Di_Glyph* end = &text->buf->glyphs[text->end];
C2Di_Glyph* cur;
CFNT_s* systemFont = fontGetSystemFont();

float glyphZ = z;
float glyphH;
float dispY;
if (text->font)
{
scaleX *= text->font->textScale;
scaleY *= text->font->textScale;
glyphH = scaleY*text->font->cfnt->finf.tglp->cellHeight;
dispY = ceilf(scaleY*text->font->cfnt->finf.lineFeed);
} else
{
scaleX *= s_textScale;
scaleY *= s_textScale;
glyphH = scaleY*fontGetGlyphInfo(systemFont)->cellHeight;
dispY = ceilf(scaleY*fontGetInfo(systemFont)->lineFeed);
}
C2D_Font font = text->font ? text->font : &g_systemFont;
scaleX *= font->textScale;
scaleY *= font->textScale;
glyphH = scaleY*font->cfnt->finf.tglp->cellHeight;
dispY = ceilf(scaleY*font->cfnt->finf.lineFeed);
u32 color = 0xFF000000;
float maxWidth = scaleX*text->width;

Expand All @@ -347,10 +314,7 @@ void C2D_DrawText(const C2D_Text* text, u32 flags, float x, float y, float z, fl

if (flags & C2D_AtBaseline)
{
if (text->font)
y -= scaleY*text->font->cfnt->finf.tglp->baselinePos;
else
y -= scaleY*fontGetGlyphInfo(systemFont)->baselinePos;
y -= scaleY*font->cfnt->finf.tglp->baselinePos;
}
if (flags & C2D_WithColor)
color = va_arg(va, u32);
Expand Down