nngn::Textures Class Reference

Texture manager, loads and caches image data from files/buffers. More...

#include <texture.h>

Collaboration diagram for nngn::Textures:

Public Types
enum class	Format : u8 { PNG = 1 , PPM }

Public Member Functions
u32	max (void) const
	Maximum number of textures that can be loaded, see set_max.
u32	n (void) const
	Number of active images in the cache.
u64	generation (void) const
	Counter incremented every time the cache is changed.
void	set_graphics (Graphics *g)
	Sets the graphics back end where textures will be uploaded.
void	set_max (u32 n)
	Sets the maximum number of textures that can be loaded.
u32	load_data (const char *name, const std::byte *p)
	Loads RGBA texture data from a buffer.
u32	load (const char *filename)
	Loads texture data from a file.
bool	reload (u32 i)
	Reloads data for a single texture.
bool	reload_all (void)
	Reloads all texture data.
bool	update_data (u32 i, const std::byte *p) const
	Updates a previously loaded texture.
void	remove (u32 i)
	Decrements a texture's reference count and cleans up if necessary.
void	add_ref (u32 i, std::size_t n=1)
	Increments the reference count of a texture.
void	add_ref (const char *filename, std::size_t n=1)
	Increments the reference count of a texture by name.
std::vector< std::tuple< std::string_view, u32 > >	dump (void) const
	Dumps name/ref_count pairs for all loaded textures.

Static Public Member Functions
static std::vector< std::byte >	read (const char *filename)
	Reads raw RGBA image data from a file.
static bool	write (const char *filename, std::span< const std::byte > s, Format fmt)
	Writes raw RGBA image data to a file.
static void	red_to_rgba (std::span< std::byte > dst, std::span< const std::byte > src)
	Expands single-channel data into full RGBA.
static void	flip_y (std::span< std::byte > s)
	Reverses the rows of a buffer containing raw RGBA image data.

Private Member Functions
u32	insert (u32 i, std::string_view name, const std::byte *p)

Private Attributes
Graphics *	graphics = nullptr
std::vector< Hash >	hashes = {{}}
std::vector< u32 >	counts = {1}
std::vector< std::string >	names = {{}}
u64	gen = 0

Detailed Description

Texture manager, loads and caches image data from files/buffers.

All images are assumed to be rectangular and of Graphics::TEXTURE_EXTENT size. Attempting to load images with the wrong size from a file will fail. If a graphics back end is set (via set_graphics), texture data is uploaded to it via Graphics::load_textures.

Image data is associated with a string ID (usually the file name) and a reference count. Future loads with the same ID will simply increment the reference count (image data, if provided, is ignored). When a texture is removed, the reference count is decremented. No special action is taken when it reaches zero, but the slot is then considered unused and the ID will be reused in future loads.

The index 0 is special: it is pre-allocated when the object is initialized and returned in case of errors. It is a texture with no associated data.

Member Enumeration Documentation

Format

enum class nngn::Textures::Format : u8

strong

Enumerator
PNG
PPM

Member Function Documentation

add_ref() [1/2]

void nngn::Textures::add_ref	(	const char *	filename,
		std::size_t	n = 1 )

Increments the reference count of a texture by name.

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add_ref() [2/2]

void nngn::Textures::add_ref	(	u32	i,
		std::size_t	n = 1 )

Increments the reference count of a texture.

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dump()

std::vector< std::tuple< std::string_view, u32 > > nngn::Textures::dump

(

void

)

const

Dumps name/ref_count pairs for all loaded textures.

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flip_y()

void nngn::Textures::flip_y ( std::span< std::byte > s )

static

Reverses the rows of a buffer containing raw RGBA image data.

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generation()

u64 nngn::Textures::generation ( void ) const

inline

Counter incremented every time the cache is changed.

Can be used to quickly track changes across frames, e.g. by an external tool to know when to call dump.

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insert()

u32 nngn::Textures::insert ( u32 i, std::string_view name, const std::byte * p )

private

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load()

u32 nngn::Textures::load

(

const char *

filename

)

Loads texture data from a file.

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load_data()

u32 nngn::Textures::load_data	(	const char *	name,
		const std::byte *	p )

Loads RGBA texture data from a buffer.

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max()

u32 nngn::Textures::max ( void ) const

inline

Maximum number of textures that can be loaded, see set_max.

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n()

u32 nngn::Textures::n

(

void

)

const

Number of active images in the cache.

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read()

std::vector< std::byte > nngn::Textures::read ( const char * filename )

static

Reads raw RGBA image data from a file.

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red_to_rgba()

void nngn::Textures::red_to_rgba ( std::span< std::byte > dst, std::span< const std::byte > src )

static

Expands single-channel data into full RGBA.

Each pixel value is replicated three times, one for each channel.

Parameters

dst	Buffer of nngn::Graphics::TEXTURE_SIZE size.
src	Source buffer of size dst.size() / 4 containing the single-channel values to be replicated.

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reload()

bool nngn::Textures::reload

(

u32

i

)

Reloads data for a single texture.

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reload_all()

bool nngn::Textures::reload_all

(

void

)

Reloads all texture data.

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remove()

void nngn::Textures::remove

(

u32

i

)

Decrements a texture's reference count and cleans up if necessary.

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set_graphics()

void nngn::Textures::set_graphics ( Graphics * g )

inline

Sets the graphics back end where textures will be uploaded.

This method does not load any data, any pre-existing textures have to be reloaded (see reload and reload_all).

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set_max()

void nngn::Textures::set_max

(

u32

n

)

Sets the maximum number of textures that can be loaded.

Attempting to perform a load beyond this limit will fail, unless the texture is already in the cache. It is assumed that the graphics back end has been configured to hold at least n textures.

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update_data()

bool nngn::Textures::update_data	(	u32	i,
		const std::byte *	p ) const

Updates a previously loaded texture.

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write()

bool nngn::Textures::write ( const char * filename, std::span< const std::byte > s, Format fmt )

static

Writes raw RGBA image data to a file.

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Member Data Documentation

counts

std::vector<u32> nngn::Textures::counts = {1}

private

gen

u64 nngn::Textures::gen = 0

private

graphics

Graphics* nngn::Textures::graphics = nullptr

private

hashes

std::vector<Hash> nngn::Textures::hashes = {{}}

private

names

std::vector<std::string> nngn::Textures::names = {{}}

private

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

• src/graphics/texture.h
• src/graphics/texture.cpp