SdfAtlas Class Reference

Loads a TTF font, bakes an SDF glyph atlas, and uploads it to the GPU. More...

#include <SdfAtlas.hpp>

Public Member Functions
bool	init (SDL_GPUDevice *dev, const char *ttfPath)
	Load TTF from path, bake SDF, upload to GPU.
void	quit ()
	Release GPU resources owned by this atlas.
const GlyphInfo *	glyph (uint32_t codepoint) const
	Look up glyph metrics.
void	bindFragment (SDL_GPURenderPass *pass, uint32_t slot) const
	Bind the SDF atlas texture and sampler to a fragment sampler slot.
float	scale () const
	Raw scale factor: bake pixels per em unit.
bool	ready () const
	Check whether the atlas has been successfully initialised.
SDL_GPUTexture *	gpuTexture () const
	GPU texture containing the baked SDF atlas (R8_UNORM, 1024x1024).
SDL_GPUSampler *	gpuSampler () const
	Linear-clamp sampler for the SDF atlas.

Static Public Attributes
static constexpr int	k_atlasW = 1024
static constexpr int	k_atlasH = 1024
static constexpr int	k_renderPx = 72
	Rasterisation size in pixels.
static constexpr int	k_spread = 12
	SDF spread in pixels.

Private Attributes
SDL_GPUDevice *	device_ = nullptr
SDL_GPUTexture *	texture_ = nullptr
SDL_GPUSampler *	sampler_ = nullptr
GlyphMap	glyphs_
float	scale_ = 1.f

Detailed Description

Loads a TTF font, bakes an SDF glyph atlas, and uploads it to the GPU.

Uses stb_truetype's analytic SDF generator (stbtt_GetCodepointSDF) to compute distance fields directly from font vector outlines, then packs them into a 1024x1024 R8_UNORM atlas texture.

Member Function Documentation

bindFragment()

void SdfAtlas::bindFragment	(	SDL_GPURenderPass *	pass,
		uint32_t	slot ) const

Bind the SDF atlas texture and sampler to a fragment sampler slot.

Parameters

pass	Active render pass.
slot	Fragment sampler slot index.

glyph()

const GlyphInfo * SdfAtlas::glyph ( uint32_t codepoint ) const

nodiscard

Look up glyph metrics.

Look up glyph metrics by Unicode codepoint.

Parameters

codepoint

Unicode codepoint to look up.

Returns

Pointer to glyph info, or nullptr if the codepoint was not baked.

gpuSampler()

SDL_GPUSampler * SdfAtlas::gpuSampler ( ) const

inlinenodiscard

Linear-clamp sampler for the SDF atlas.

Returns

SDL GPU sampler handle.

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gpuTexture()

SDL_GPUTexture * SdfAtlas::gpuTexture ( ) const

inlinenodiscard

GPU texture containing the baked SDF atlas (R8_UNORM, 1024x1024).

Returns

SDL GPU texture handle.

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init()

bool SdfAtlas::init	(	SDL_GPUDevice *	dev,
		const char *	ttfPath )

Load TTF from path, bake SDF, upload to GPU.

Parameters

dev	GPU device to upload the atlas texture to.
ttfPath	Filesystem path to the TTF font file.

Returns

true on success.

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quit()

void SdfAtlas::quit

(

)

Release GPU resources owned by this atlas.

Release all GPU resources and reset internal state.

ready()

bool SdfAtlas::ready ( ) const

inlinenodiscard

Check whether the atlas has been successfully initialised.

Returns

true if the GPU texture is valid.

scale()

float SdfAtlas::scale ( ) const

inlinenodiscard

Raw scale factor: bake pixels per em unit.

Returns

Scale factor used during atlas bake.

Member Data Documentation

device_

SDL_GPUDevice* SdfAtlas::device_ = nullptr

private

glyphs_

GlyphMap SdfAtlas::glyphs_

private

k_atlasH

int SdfAtlas::k_atlasH = 1024

staticconstexpr

k_atlasW

int SdfAtlas::k_atlasW = 1024

staticconstexpr

k_renderPx

int SdfAtlas::k_renderPx = 72

staticconstexpr

Rasterisation size in pixels.

k_spread

int SdfAtlas::k_spread = 12

staticconstexpr

SDF spread in pixels.

sampler_

SDL_GPUSampler* SdfAtlas::sampler_ = nullptr

private

scale_

float SdfAtlas::scale_ = 1.f

private

texture_

SDL_GPUTexture* SdfAtlas::texture_ = nullptr

private

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The documentation for this class was generated from the following files:

• src/client/particles/sdf/SdfAtlas.hpp
• src/client/particles/sdf/SdfAtlas.cpp