bitmaps.cpp File Reference

#include "components/rendering/rendering.h"
#include <bx/allocator.h>
#include "api/v1/types/tags/classes/bitmap.h"
#include "components/diagnostics/logger/logger.h"
#include "components/rendering/bgfx/texture_storage.h"

Include dependency graph for bitmaps.cpp:

Classes
struct	bgfx_texture_info_data
	Data structure used to group together information about a texture. More...

Functions
bgfx::TextureFormat::Enum	determine_gpu_pixel_format (bitmap::format_enum tag_format)
	Converts a bitmap pixel format enum value to the equivalent bgfx pixel format. More...
bgfx_texture_info_data *	create_default_color_texture (uint32_t color)
uint32_t	compute_sampler_flags_from_bitmap (bitmap *bitmap_tag)
	Determines sampler flags from a bitmap tag. More...
float	srgb_to_linear (float srgb_value)
	Converts a single sRGB-encoded color channel value to linear space. More...
float	linear_to_srgb (float linear_value)
	Converts a single linear-space color channel value to sRGB encoding. More...
void	downsample_mip_2x2 (const uint8_t *source, int source_width, int source_height, uint8_t *destination, int destination_width, int destination_height, bool treat_as_srgb)
	Generates the next mip level for an RGBA8 texture by averaging 2x2 pixel blocks. More...
int	compute_mip_count (int width, int height)
	Computes the number of mip levels for a 2D texture of the given dimensions. More...
int	compute_mip_chain_size_rgba8 (int base_width, int base_height)
	Computes the total byte count required to hold a complete mip chain for an RGBA8 texture of the given base dimensions. More...
const bgfx::Memory *	build_mip_chain_rgba8 (const void *base_pixel_data, int base_width, int base_height, bool treat_as_srgb)
	Builds the complete mip chain for an RGBA8 texture and packages it as a bgfx::Memory pointer ready to pass to bgfx::createTexture2D. More...

Variables
bgfx::TextureHandle	default_texture = BGFX_INVALID_HANDLE
bgfx::TextureHandle	fallback_white = BGFX_INVALID_HANDLE
bgfx::TextureHandle	fallback_normal = BGFX_INVALID_HANDLE
bgfx::TextureHandle	fallback_metal_rough = BGFX_INVALID_HANDLE
bgfx::TextureHandle	fallback_gray_50 = BGFX_INVALID_HANDLE
std::unordered_map< std::string, bgfx_texture_info_data * >	bgfx_texture_map = std::unordered_map<std::string, bgfx_texture_info_data*>()
	Map containing information on all loaded textures. More...

Function Documentation

build_mip_chain_rgba8()

const bgfx::Memory* build_mip_chain_rgba8	(	const void *	base_pixel_data,
		int	base_width,
		int	base_height,
		bool	treat_as_srgb
	)

Builds the complete mip chain for an RGBA8 texture and packages it as a bgfx::Memory pointer ready to pass to bgfx::createTexture2D.

Allocates a single bgfx-managed buffer sized for the entire chain, copies the provided base data into the mip 0 region, then iteratively downsamples each subsequent mip from the previous one using a 2x2 box filter. The output is packed in the layout bgfx expects (mip 0 first, followed by each subsequent mip contiguously).

Parameters

base_pixel_data	- Pointer to the source mip 0 data (RGBA8, tightly packed).
base_width	- Width of the base texture in pixels.
base_height	- Height of the base texture in pixels.
treat_as_srgb	- Whether downsampling should be gamma-correct for color textures.

Returns

A bgfx::Memory* containing the full mip chain. Memory is bgfx-managed, so the caller does not need to free it - just pass it to createTexture2D.

Author

Claude (Opus 4.7)

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compute_mip_chain_size_rgba8()

int compute_mip_chain_size_rgba8	(	int	base_width,
		int	base_height
	)

Computes the total byte count required to hold a complete mip chain for an RGBA8 texture of the given base dimensions.

The mip chain follows the standard "halve each dimension, minimum 1" rule and terminates when both dimensions reach 1. Each mip's contribution is its width * height * 4 bytes.

Parameters

base_width	- Width of mip 0 in pixels.
base_height	- Height of mip 0 in pixels.

Returns

The sum of all mip levels' byte sizes.

Author

Claude (Opus 4.7)

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compute_mip_count()

int compute_mip_count	(	int	width,
		int	height
	)

Computes the number of mip levels for a 2D texture of the given dimensions.

The mip count is determined by the largest dimension, halved repeatedly until it reaches 1. The base level (mip 0) is always counted, so this returns at least 1.

Parameters

width	- Width of the base texture in pixels.
height	- Height of the base texture in pixels.

Returns

The number of mip levels in a complete chain from the base down to 1x1.

Author

Claude (Opus 4.7)

compute_sampler_flags_from_bitmap()

uint32_t compute_sampler_flags_from_bitmap

(

bitmap *

bitmap_tag

)

Determines sampler flags from a bitmap tag.

This will determine the sampler flags for this bitmap based on the filtering modes for this bitmap tag.

Parameters

bitmap_tag

- The bitmap tag to determine sampler flags for.

Returns

The sampler flags based on this bitmap tag. Will return 0 if the tag was nullptr.

Author

Claude (Opus 4.7)

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create_default_color_texture()

bgfx_texture_info_data* create_default_color_texture

(

uint32_t

color

)

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determine_gpu_pixel_format()

bgfx::TextureFormat::Enum determine_gpu_pixel_format

(

bitmap::format_enum

tag_format

)

Converts a bitmap pixel format enum value to the equivalent bgfx pixel format.

Parameters

tag_format

- The bitmap pixel format value to convert.

Returns

The equivalent bgfx pixel format. If no matching format is found, then bgfx::TextureFormat::Unknown is returned.

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downsample_mip_2x2()

void downsample_mip_2x2	(	const uint8_t *	source,
		int	source_width,
		int	source_height,
		uint8_t *	destination,
		int	destination_width,
		int	destination_height,
		bool	treat_as_srgb
	)

Generates the next mip level for an RGBA8 texture by averaging 2x2 pixel blocks.

When sRGB correctness is requested, the color channels (RGB) are converted to linear space before averaging and converted back to sRGB afterward. This avoids the brightness-shift artifact that occurs when sRGB-encoded values are averaged directly. Alpha is always averaged in raw bytes since it isn't gamma encoded. Source data is sampled with edge-clamp behavior so non-power-of-two dimensions are handled correctly.

Parameters

source	- Pointer to the source mip's pixel buffer (RGBA8, tightly packed).
source_width	- Width in pixels of the source buffer.
source_height	- Height in pixels of the source buffer.
destination	- Pointer to the destination buffer to write the new mip into.
destination_width	- Width in pixels of the destination buffer.
destination_height	- Height in pixels of the destination buffer.
treat_as_srgb	- If true, RGB channels go through gamma-correct averaging.

Author

Claude (Opus 4.7)

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linear_to_srgb()

float linear_to_srgb

(

float

linear_value

)

Converts a single linear-space color channel value to sRGB encoding.

The inverse of srgb_to_linear. Used after averaging color values in linear space to produce a result that's correctly gamma-encoded for storage in an sRGB texture.

Parameters

linear_value

- The linear-space value, normalized to the [0, 1] range.

Returns

The equivalent sRGB-encoded value, also in the [0, 1] range.

Author

Claude (Opus 4.7)

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srgb_to_linear()

float srgb_to_linear

(

float

srgb_value

)

Converts a single sRGB-encoded color channel value to linear space.

Uses the proper piecewise transform from the sRGB specification rather than the gamma-2.2 approximation. The piecewise version handles values near black more accurately - the gamma curve goes flat in that region and a pure power function would produce slightly wrong results.

Parameters

srgb_value

- The sRGB-encoded value, normalized to the [0, 1] range.

Returns

The equivalent value in linear color space, also in the [0, 1] range.

Author

Claude (Opus 4.7)

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Variable Documentation

bgfx_texture_map

std::unordered_map<std::string, bgfx_texture_info_data*> bgfx_texture_map = std::unordered_map<std::string, bgfx_texture_info_data*>()

Map containing information on all loaded textures.

Each key contains the tag path of the texture's bitmap tag, and each value stores the texture information structure.

default_texture

bgfx::TextureHandle default_texture = BGFX_INVALID_HANDLE

fallback_gray_50

bgfx::TextureHandle fallback_gray_50 = BGFX_INVALID_HANDLE

fallback_metal_rough

bgfx::TextureHandle fallback_metal_rough = BGFX_INVALID_HANDLE

fallback_normal

bgfx::TextureHandle fallback_normal = BGFX_INVALID_HANDLE

fallback_white

bgfx::TextureHandle fallback_white = BGFX_INVALID_HANDLE