pbr.c File Reference

#include "pbr.h"
#include "gl_common.h"
#include "perf_timer.h"
#include "render_utils.h"
#include "shader.h"
#include <math.h>
#include <stddef.h>
#include <stdint.h>

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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	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_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_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_irradiance_map (GLuint shader, GLuint env_hdr_tex, int size, float threshold)
	Generates an irradiance map (diffuse IBL) in a single pass. 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...
GLuint	build_brdf_lut_map (int size)
	Generates the 2D BRDF Integration Look-Up Table. More...

Variables
static const uint32_t	COMPUTE_GROUP_SIZE_PBR = 32
static const uint32_t	COMPUTE_GROUP_SIZE_LUM = 16
static const uint32_t	MAX_HDR_RESOLUTION = 4096
static const GLuint	BINDING_ENV_MAP = 0
static const GLuint	BINDING_DEST_TEXTURE = 1
static const GLuint	COMPUTE_DISPATCH_Z_ONCE = 1

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.

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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.

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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.

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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.

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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.

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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.

Variable Documentation

BINDING_DEST_TEXTURE

const GLuint BINDING_DEST_TEXTURE = 1

static

BINDING_ENV_MAP

const GLuint BINDING_ENV_MAP = 0

static

COMPUTE_DISPATCH_Z_ONCE

const GLuint COMPUTE_DISPATCH_Z_ONCE = 1

static

COMPUTE_GROUP_SIZE_LUM

const uint32_t COMPUTE_GROUP_SIZE_LUM = 16

static

COMPUTE_GROUP_SIZE_PBR

const uint32_t COMPUTE_GROUP_SIZE_PBR = 32

static

MAX_HDR_RESOLUTION

const uint32_t MAX_HDR_RESOLUTION = 4096

static