pbr.h File Reference

Physically-Based Rendering (PBR) and Image-Based Lighting (IBL) utilities. More...

#include "gl_common.h"

Include dependency graph for pbr.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	PBRSpecUniforms
	Cached uniform locations for specular prefiltering shader. More...
struct	PBRIrrUniforms
	Cached uniform locations for radiance convolution shader. More...
struct	PBRLumUniforms
	Cached uniform locations for luminance reduction shader. More...

Functions
void	pbr_get_spec_uniforms (GLuint shader, PBRSpecUniforms *out)
	Retrieves uniform locations for the specular prefilter shader. More...
void	pbr_get_irr_uniforms (GLuint shader, PBRIrrUniforms *out)
	Retrieves uniform locations for the irradiance convolution shader. More...
void	pbr_get_lum_uniforms (GLuint shader, PBRLumUniforms *out)
	Retrieves uniform locations for the luminance reduction shader. More...
GLuint	build_prefiltered_specular_map (GLuint shader, GLuint env_hdr_tex, int width, int height, float threshold)
	Generates a pre-filtered specular environment map in a single pass. More...
GLuint	pbr_prefilter_init (int width, int height)
	Initializes a texture for progressive specular pre-filtering. More...
void	pbr_prefilter_mip (GLuint shader, const PBRSpecUniforms *uniforms, GLuint env_hdr_tex, GLuint dest_tex, int width, int height, int level, int total_levels, int slice_index, int total_slices, float threshold)
	Computes a single slice or mip-level for progressive pre-filtering. More...
GLuint	build_irradiance_map (GLuint shader, GLuint env_hdr_tex, int size, float threshold)
	Generates an irradiance map (diffuse IBL) in a single pass. More...
GLuint	pbr_irradiance_init (int size)
	Initializes a texture for progressive irradiance computation. More...
void	pbr_irradiance_slice_compute (GLuint shader, const PBRIrrUniforms *uniforms, GLuint env_hdr_tex, GLuint dest_tex, int size, int slice_index, int total_slices, float threshold)
	Computes one face/slice of the irradiance map. More...
GLuint	build_brdf_lut_map (int size)
	Generates the 2D BRDF Integration Look-Up Table. More...
void	compute_mean_luminance_gpu_start (GLuint shader_pass1, GLuint shader_pass2, GLuint hdr_tex, int width, int height, GLuint ssbos[2], const PBRLumUniforms *uniforms)
	Starts the GPU computation for mean luminance (non-blocking). Uses a two-pass parallel reduction via compute shaders and SSBOs. More...
float	compute_mean_luminance_gpu_result (GLuint ssbos[2], float clamp_multiplier)
	Reads the result of mean luminance computation from the SSBO. This function should be called only after the GPU has finished the computation started by compute_mean_luminance_gpu_start. More...

Detailed Description

Physically-Based Rendering (PBR) and Image-Based Lighting (IBL) utilities.

This module handles the generation of pre-filtered environment maps (specular, irradiance, BRDF LUT) and GPU-accelerated luminance computation.

Function Documentation

build_brdf_lut_map()

GLuint build_brdf_lut_map

(

int

size

)

Generates the 2D BRDF Integration Look-Up Table.

Parameters

size	LUT resolution (width and height).

Returns

GLuint handle of the 2D RG texture.

Here is the call graph for this function:

build_irradiance_map()

GLuint build_irradiance_map	(	GLuint	shader,
		GLuint	env_hdr_tex,
		int	size,
		float	threshold
	)

Generates an irradiance map (diffuse IBL) in a single pass.

Parameters

shader	Irradiance convolution shader.
env_hdr_tex	Source HDR map.
size	Destination resolution (width/height).
threshold	Luminance threshold.

Returns

GLuint handle of the irradiance cubemap.

Here is the call graph for this function:

build_prefiltered_specular_map()

GLuint build_prefiltered_specular_map	(	GLuint	shader,
		GLuint	env_hdr_tex,
		int	width,
		int	height,
		float	threshold
	)

Generates a pre-filtered specular environment map in a single pass.

Parameters

shader	Prefiltering compute shader.
env_hdr_tex	Source HDR environment map.
width	Destination width.
height	Destination height.
threshold	Luminance threshold for importance sampling.

Returns

GLuint handle of the generated cubemap.

Here is the call graph for this function:

compute_mean_luminance_gpu_result()

float compute_mean_luminance_gpu_result	(	GLuint	ssbos[2],
		float	clamp_multiplier
	)

Reads the result of mean luminance computation from the SSBO. This function should be called only after the GPU has finished the computation started by compute_mean_luminance_gpu_start.

Parameters

ssbos	The SSBOs used in the computation.
clamp_multiplier	Multiplier to apply to the result.

Returns

The computed mean luminance.

compute_mean_luminance_gpu_start()

void compute_mean_luminance_gpu_start	(	GLuint	shader_pass1,
		GLuint	shader_pass2,
		GLuint	hdr_tex,
		int	width,
		int	height,
		GLuint	ssbos[2],
		const PBRLumUniforms *	uniforms
	)

Starts the GPU computation for mean luminance (non-blocking). Uses a two-pass parallel reduction via compute shaders and SSBOs.

Parameters

shader_pass1	First reduction pass shader.
shader_pass2	Final reduction pass shader.
hdr_tex	Source HDR texture.
width	Texture width.
height	Texture height.
ssbos	Pair of SSBO handles for intermediate and final results.
uniforms	Cached uniform locations for pass 2.

pbr_get_irr_uniforms()

void pbr_get_irr_uniforms	(	GLuint	shader,
		PBRIrrUniforms *	out
	)

Retrieves uniform locations for the irradiance convolution shader.

Parameters

shader	The shader program.
out	Pointer to the struct to populate.

pbr_get_lum_uniforms()

void pbr_get_lum_uniforms	(	GLuint	shader,
		PBRLumUniforms *	out
	)

Retrieves uniform locations for the luminance reduction shader.

Parameters

shader	The shader program.
out	Pointer to the struct to populate.

pbr_get_spec_uniforms()

void pbr_get_spec_uniforms	(	GLuint	shader,
		PBRSpecUniforms *	out
	)

Retrieves uniform locations for the specular prefilter shader.

Parameters

shader	The shader program.
out	Pointer to the struct to populate.

pbr_irradiance_init()

GLuint pbr_irradiance_init

(

int

size

)

Initializes a texture for progressive irradiance computation.

Parameters

size	Destination resolution.

Returns

GLuint handle of the empty cubemap.

Here is the call graph for this function:

pbr_irradiance_slice_compute()

void pbr_irradiance_slice_compute	(	GLuint	shader,
		const PBRIrrUniforms *	uniforms,
		GLuint	env_hdr_tex,
		GLuint	dest_tex,
		int	size,
		int	slice_index,
		int	total_slices,
		float	threshold
	)

Computes one face/slice of the irradiance map.

Parameters

shader	Compute shader.
uniforms	Cached uniform locations.
env_hdr_tex	Source HDR map.
dest_tex	Destination cubemap.
size	Resolution.
slice_index	Current face.
total_slices	Total faces.
threshold	Luminance threshold.

Note

This function does NOT issue a memory barrier. The caller must call glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT) once after all slices have been dispatched.

pbr_prefilter_init()

GLuint pbr_prefilter_init	(	int	width,
		int	height
	)

Initializes a texture for progressive specular pre-filtering.

Parameters

width	Base level width.
height	Base level height.

Returns

GLuint handle of the empty cubemap with allocated mips.

Here is the call graph for this function:

pbr_prefilter_mip()

void pbr_prefilter_mip	(	GLuint	shader,
		const PBRSpecUniforms *	uniforms,
		GLuint	env_hdr_tex,
		GLuint	dest_tex,
		int	width,
		int	height,
		int	level,
		int	total_levels,
		int	slice_index,
		int	total_slices,
		float	threshold
	)

Computes a single slice or mip-level for progressive pre-filtering.

Parameters

shader	Compute shader.
uniforms	Cached uniform locations.
env_hdr_tex	Source HDR map.
dest_tex	Destination cubemap.
width	Current level width.
height	Current level height.
level	Current mip level being processed.
total_levels	Total number of mips in the cubemap.
slice_index	Current face/slice being processed.
total_slices	Total slices (usually 6).
threshold	Luminance threshold.

Note

This function does NOT issue a memory barrier. The caller must call glMemoryBarrier(GL_SHADER_IMAGE_ACCESS_BARRIER_BIT) once after all slices have been dispatched.