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engine/shaders: add camera post-processing, split up 

We now also use shaderc instead of glslandValidator, which has #include.
ecs
q3k 2020-07-26 15:26:40 +02:00
parent f5ae25214a
commit 1ce2889608
7 changed files with 247 additions and 164 deletions
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3
engine/shaders/BUILD
View File

@ -12,8 +12,9 @@ glsl_binary(
name = "forward_frag",
srcs = [
"forward.frag",
"forward_brdf.frag",
#"forward_camera.frag",
"forward_defs.frag",
],
visibility = ["//engine:__pkg__"],
)

189
engine/shaders/forward.frag
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@ -17,126 +17,38 @@
// Abrasion. If not, see <https://www.gnu.org/licenses/>.
//
// vim: set ft=glsl:
#version 450
#extension GL_ARB_separate_shader_objects : enable
// We implement a Lambertiand & Cook-Torrance BRDF-based lighting system.
// All of this is based on a number of scientific papers, meta-studies and modern sources. We do
// our best to cite as much as possible for future reference.
// Most of the maths is used straight from [Kar13].
//
// A good summary of different research is available this blog post by Brian Karis, that attempts
// to catalogue all existing BRDF-related functions:
// http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
//
/// Bibliography:
//
// [Bec63]
// P. Beckmann & A. Spizzichino. 1963. "The Scattering of Electromagnetic Waves from Rough Surfaces"
// MacMillan, New York
//
// [Smi67]
// Bruce Smith. 1967. "Geometrical shadowing of a random rough surface."
// IEEE transactions on antennas and propagation 15.5 (1967): 668-671.
//
// [CT82]
// Robert L. Cook, Kenneth E. Torrance. 1982. "A Reflectance Model for Computer Graphics"
// ACM Transactions on Graphics, 1(1), 7–24.
// doi: 10.1145/357290.357293
//
// [Sch94]
// Christophe Schlick. 1994. "An Inexpensive BRDF Model for Physically-based Rendering"
// Computer Graphics Forum, 13(3), 233–246.
// doi: 10.1111/1467-8659.1330233
//
// [Wa07]
// Bruce Walter et al. 2007. "Microfacet Models for Refraction through Rough Surfaces."
// Proceedings of the Eurographics Symposium on Rendering.
//
// [Bur12]
// Brent Burley. 2012. "Physically-Based Shading at Disney"
// URL: https://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_notes_v2.pdf
//
// [Kar13]
// Brian Karis. 2013. "Real Shading in Unreal Engine 4"
// URL: https://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
//
// [Hei14]
// Eric Heitz. 2014. "Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs"
// Journal of Computer Graphics Techniques, 3 (2).
//
// [GA19]
// Romain Guy, Mathias Agopian, "Physically Based Rendering in Filament"
// URL: https://google.github.io/filament/Filament.html
#include "forward_defs.frag"
#include "forward_brdf.frag"
struct OmniLight {
vec4 pos;
vec4 color;
};
/// Camera settings.
// Aperture (in f-stops)
const float CAMERA_APERTURE = 4.0; // f/8 and be there
// Shutter speed (in seconds)
const float CAMERA_SHUTTER = 1.0 / 60; // 180° shutter at 30FPS.
// Film sensitivity ('ISO')
const float CAMERA_SENSITIVITY = 3200.0;
layout(binding = 0) uniform FragmentUniformBufferObject {
vec4 cameraPos;
OmniLight omniLights[4];
} ubo;
layout(binding = 1) uniform sampler2D texSamplerDiffuse;
layout(binding = 2) uniform sampler2D texSamplerRoughness;
// Exposure Value at ISO 100, per [Ray00] equation (12).
const float CAMERA_EV_100 = log2((CAMERA_APERTURE * CAMERA_APERTURE)/CAMERA_SHUTTER);
// Exposure value at CAMERA_SENSITIVITY
const float CAMERA_EV = CAMERA_EV_100 - log2(CAMERA_SENSITIVITY / 100);
const float CAMERA_EXPOSURE = 1.0 / (pow(2.0, CAMERA_EV) * 1.2);
layout(location = 0) in vec2 fragTexCoord;
layout(location = 1) in vec3 fragWorldPos;
layout(location = 2) in vec3 fragNormal;
const mat3 XYZ_TO_SRGB = mat3(
3.2406, -0.9689, 0.0557,
-1.5372, 1.8758, -0.2040,
-0.4986, 0.0415, 1.0570
);
layout(location = 0) out vec4 outColor;
const float PI = 3.14159;
// [Sch94] Fresnel approximation, used for F in Cook-Torrance BRDF.
vec3 FresnelSchlick(float HdotV, vec3 F0) {
return F0 + (1.0 - F0) * pow(1.0 - HdotV, 5.0);
}
// Microfacet Normal Distribution Function, used for D in Cook-Torrance BRDF.
float DistributionGGX(float NdotH, float roughness) {
// 'Roughness remapping' as per [Bur12]
float a = roughness * roughness;
// NDF from [Kar13], that cites [Bur12], which in turn cites [Wa07].
// However, I could not find the same equation form in [Bur12] or deduce it myself from [Wa07],
// and ended up taking the direct, untraceable form from [Kar13], so take this with a grain of salt.
float a2 = a * a;
float NdotH2 = NdotH * NdotH;
float denom = (NdotH2 * (a2 - 1.0) + 1.0);
return (a * a) / (PI * denom * denom);
}
float GeometrySchlickGGX(float NdotV, float roughness) {
// Remapping of K for analytical (non-IBL) lighting per [Kar13].
float r = (roughness + 1.0);
float k = (r * r) / 8.0;
// [Sch94] approximation of [Smi67] equation for [Bec63].
return (NdotV) / (NdotV * (1.0 - k) + k);
}
// Geometric shadowing function, used for G in Cook-Torrance BRDF.
float GeometrySmith(float NdotV, float NdotL, float roughness) {
// Smith geometric shadowing function.
// [GA19] cites [Hei14] as demonstrating [Smi97] to be correct.
float ggx2 = GeometrySchlickGGX(NdotV, roughness);
float ggx1 = GeometrySchlickGGX(NdotL, roughness);
return ggx1 * ggx2;
}
// Cook-Torrance [CT82] specular model.
vec3 SpecularCookTorrance(float NdotH, float NdotV, float NdotL, vec3 F, float roughness) {
float NDF = DistributionGGX(NdotH, roughness);
float G = GeometrySmith(NdotV, NdotL, roughness);
// F is taken in as a pre-computed argument for optimization purposes (it's reused for the
// lambertian component of the lighting model).
// Form from [Kar13], decuced from [CT82].
vec3 specular = (NDF * G * F) / max((4.0 * NdotV * NdotL), 0.0001);
return specular;
float GammaCorrect(float v) {
if (v <= 0.0031308) {
return 12.92 * v;
}
return 1.055 * pow(v, (1.0/2.4)) - 0.055;
}
@ -162,52 +74,9 @@ void main() {
vec3 F0 = vec3(0.04);
F0 = mix(F0, albedo, metallic);
// Luminance of this fragment.
// Luminance is defined as the sum (integral) of all ilncoming illuminance over the half-sphere
// 'above' that point. As we currently only support analytic lighting (ie. omni lights), we
// integrate by iterating over all luminance sources, that currently are point lights.
vec3 Lo = vec3(0.0);
for (int i = 0; i < 3; ++i) {
vec3 lightPos = ubo.omniLights[i].pos.xyz;
vec3 lightColor = ubo.omniLights[i].color.xyz;
// Unit vector pointing at light from fragment.
vec3 L = normalize(lightPos - fragWorldPos);
// Half-vector between to-light and to-camera unit vectors.
vec3 H = normalize(V + L);
// Dot products re-used across further computation for this (fragment, light) pair.
float HdotV = max(dot(H, V), 0.0);
float NdotH = max(dot(N, H), 0.0);
float NdotV = max(dot(N, V), 0.0);
float NdotL = max(dot(N, L), 0.0);
// Translate luminous flux (lumen) into luminous intensity at this solid angle (candela).
// This follows the derivation in [GA19] (58).
float distance = length(lightPos - fragWorldPos);
vec3 intensity = (lightColor / (4 * PI * (distance * distance)));
// The Fresnel component from the Cook-Torrance specular BRDF is also used to calculate the
// lambertian diffuse weight kD. We calculate it outside of the function.
vec3 F = FresnelSchlick(HdotV, F0);
// Cook-Torrance specular value.
vec3 specular = SpecularCookTorrance(NdotH, NdotV, NdotL, F, roughness);
// Lambertian diffuse component, influenced by fresnel and dielectric/metalness.
vec3 kD = (vec3(1.0) - F) * dielectric;
// Lambertian diffuse value.
vec3 diffuse = albedo / PI;
// Illuminance for this point from this light is a result of scaling the luminous
// intensity of this light by the BRDL and by (N o L). This follows the definitions
// of illuminance and luminous intensity.
vec3 Li = (kD * diffuse + specular) * intensity * NdotL;
// Integration of luminance from illuminance.
Lo += Li;
}
vec3 Lo = BRDFIlluminance(N, V, F0, albedo, dielectric, roughness);
vec3 ambient = vec3(0.00) * albedo;
vec3 color = ambient + Lo;
outColor = vec4(color, 1.0);
vec3 color = XYZ_TO_SRGB * ((ambient + Lo) * CAMERA_EXPOSURE);
outColor = vec4(GammaCorrect(color.x), GammaCorrect(color.y), GammaCorrect(color.z), 1.0);
}

166
engine/shaders/forward_brdf.frag Normal file
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@ -0,0 +1,166 @@
// Copyright 2020 Sergiusz 'q3k' Bazanski <q3k@q3k.org>
//
// This file is part of Abrasion.
//
// Abrasion is free software: you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation, version 3.
//
// Abrasion is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details.
//
// You should have received a copy of the GNU General Public License along with
// Abrasion. If not, see <https://www.gnu.org/licenses/>.
//
// vim: set ft=glsl:
// We implement a Lambertiand & Cook-Torrance BRDF-based lighting system.
// All of this is based on a number of scientific papers, meta-studies and modern sources. We do
// our best to cite as much as possible for future reference.
// Most of the maths is used straight from [Kar13].
//
// A good summary of different research is available this blog post by Brian Karis, that attempts
// to catalogue all existing BRDF-related functions:
// http://graphicrants.blogspot.com/2013/08/specular-brdf-reference.html
//
/// Bibliography:
//
// [Bec63]
// P. Beckmann & A. Spizzichino. 1963. "The Scattering of Electromagnetic Waves from Rough Surfaces"
// MacMillan, New York
//
// [Smi67]
// Bruce Smith. 1967. "Geometrical shadowing of a random rough surface."
// IEEE transactions on antennas and propagation 15.5 (1967): 668-671.
//
// [CT82]
// Robert L. Cook, Kenneth E. Torrance. 1982. "A Reflectance Model for Computer Graphics"
// ACM Transactions on Graphics, 1(1), 7–24.
// doi: 10.1145/357290.357293
//
// [Sch94]
// Christophe Schlick. 1994. "An Inexpensive BRDF Model for Physically-based Rendering"
// Computer Graphics Forum, 13(3), 233–246.
// doi: 10.1111/1467-8659.1330233
//
// [Wa07]
// Bruce Walter et al. 2007. "Microfacet Models for Refraction through Rough Surfaces."
// Proceedings of the Eurographics Symposium on Rendering.
//
// [Bur12]
// Brent Burley. 2012. "Physically-Based Shading at Disney"
// URL: https://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_notes_v2.pdf
//
// [Kar13]
// Brian Karis. 2013. "Real Shading in Unreal Engine 4"
// URL: https://blog.selfshadow.com/publications/s2013-shading-course/karis/s2013_pbs_epic_notes_v2.pdf
//
// [Hei14]
// Eric Heitz. 2014. "Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs"
// Journal of Computer Graphics Techniques, 3 (2).
//
// [GA19]
// Romain Guy, Mathias Agopian, "Physically Based Rendering in Filament"
// URL: https://google.github.io/filament/Filament.html
#include "forward_defs.frag"
// [Sch94] Fresnel approximation, used for F in Cook-Torrance BRDF.
vec3 FresnelSchlick(float HdotV, vec3 F0) {
return F0 + (1.0 - F0) * pow(1.0 - HdotV, 5.0);
}
// Microfacet Normal Distribution Function, used for D in Cook-Torrance BRDF.
float DistributionGGX(float NdotH, float roughness) {
// 'Roughness remapping' as per [Bur12]
float a = roughness * roughness;
// NDF from [Kar13], that cites [Bur12], which in turn cites [Wa07].
// However, I could not find the same equation form in [Bur12] or deduce it myself from [Wa07],
// and ended up taking the direct, untraceable form from [Kar13], so take this with a grain of salt.
float a2 = a * a;
float NdotH2 = NdotH * NdotH;
float denom = (NdotH2 * (a2 - 1.0) + 1.0);
return (a * a) / (PI * denom * denom);
}
float GeometrySchlickGGX(float NdotV, float roughness) {
// Remapping of K for analytical (non-IBL) lighting per [Kar13].
float r = (roughness + 1.0);
float k = (r * r) / 8.0;
// [Sch94] approximation of [Smi67] equation for [Bec63].
return (NdotV) / (NdotV * (1.0 - k) + k);
}
// Geometric shadowing function, used for G in Cook-Torrance BRDF.
float GeometrySmith(float NdotV, float NdotL, float roughness) {
// Smith geometric shadowing function.
// [GA19] cites [Hei14] as demonstrating [Smi97] to be correct.
float ggx2 = GeometrySchlickGGX(NdotV, roughness);
float ggx1 = GeometrySchlickGGX(NdotL, roughness);
return ggx1 * ggx2;
}
// Cook-Torrance [CT82] specular model.
vec3 SpecularCookTorrance(float NdotH, float NdotV, float NdotL, vec3 F, float roughness) {
float NDF = DistributionGGX(NdotH, roughness);
float G = GeometrySmith(NdotV, NdotL, roughness);
// F is taken in as a pre-computed argument for optimization purposes (it's reused for the
// lambertian component of the lighting model).
// Form from [Kar13], decuced from [CT82].
vec3 specular = (NDF * G * F) / max((4.0 * NdotV * NdotL), 0.0001);
return specular;
}
vec3 BRDFIlluminance(vec3 N, vec3 V, vec3 F0, vec3 albedo, float dielectric, float roughness) {
// Luminance of this fragment.
// Luminance is defined as the sum (integral) of all ilncoming illuminance over the half-sphere
// 'above' that point. As we currently only support analytic lighting (ie. omni lights), we
// integrate by iterating over all luminance sources, that currently are point lights.
vec3 Lo = vec3(0.0);
for (int i = 0; i < 4; ++i) {
vec3 lightPos = ubo.omniLights[i].pos.xyz;
vec3 lightColor = ubo.omniLights[i].color.xyz;
// Unit vector pointing at light from fragment.
vec3 L = normalize(lightPos - fragWorldPos);
// Half-vector between to-light and to-camera unit vectors.
vec3 H = normalize(V + L);
// Dot products re-used across further computation for this (fragment, light) pair.
float HdotV = max(dot(H, V), 0.0);
float NdotH = max(dot(N, H), 0.0);
float NdotV = max(dot(N, V), 0.0);
float NdotL = max(dot(N, L), 0.0);
// Translate luminous flux (lumen) into luminous intensity at this solid angle (candela).
// This follows the derivation in [GA19] (58).
float distance = length(lightPos - fragWorldPos);
vec3 intensity = (lightColor / (4 * PI * (distance * distance)));
// The Fresnel component from the Cook-Torrance specular BRDF is also used to calculate the
// lambertian diffuse weight kD. We calculate it outside of the function.
vec3 F = FresnelSchlick(HdotV, F0);
// Cook-Torrance specular value.
vec3 specular = SpecularCookTorrance(NdotH, NdotV, NdotL, F, roughness);
// Lambertian diffuse component, influenced by fresnel and dielectric/metalness.
vec3 kD = (vec3(1.0) - F) * dielectric;
// Lambertian diffuse value.
vec3 diffuse = albedo / PI;
// Illuminance for this point from this light is a result of scaling the luminous
// intensity of this light by the BRDL and by (N o L). This follows the definitions
// of illuminance and luminous intensity.
vec3 Li = (kD * diffuse + specular) * intensity * NdotL;
// Integration of luminance from illuminance.
Lo += Li;
}
return Lo;
}

44
engine/shaders/forward_defs.frag Normal file
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@ -0,0 +1,44 @@
// Forward rendering fragment shader.
//
// Copyright 2020 Sergiusz 'q3k' Bazanski <q3k@q3k.org>
//
// This file is part of Abrasion.
//
// Abrasion is free software: you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation, version 3.
//
// Abrasion is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
// details.
//
// You should have received a copy of the GNU General Public License along with
// Abrasion. If not, see <https://www.gnu.org/licenses/>.
//
// vim: set ft=glsl:
#ifndef _FORWARD_DEFS_FRAG_
#define _FORWARD_DEFS_FRAG_
const float PI = 3.14159;
struct OmniLight {
vec4 pos;
vec4 color;
};
layout(binding = 0) uniform FragmentUniformBufferObject {
vec4 cameraPos;
OmniLight omniLights[4];
} ubo;
layout(binding = 1) uniform sampler2D texSamplerDiffuse;
layout(binding = 2) uniform sampler2D texSamplerRoughness;
layout(location = 0) in vec2 fragTexCoord;
layout(location = 1) in vec3 fragWorldPos;
layout(location = 2) in vec3 fragNormal;
layout(location = 0) out vec4 outColor;
#endif

2
engine/src/render/light.rs
View File

@ -43,7 +43,7 @@ impl Omni {
pub fn test(position: cgm::Vector3<f32>) -> Self {
Self {
position,
color: color::XYZ::new(234.7, 214.1, 207.9),
color: color::XYZ::new(234.7*10.0, 214.1*10.0, 207.9*10.0),
// TODO: use a better method
id: time::SystemTime::now().duration_since(time::UNIX_EPOCH).unwrap().as_nanos() as u64,
}

1
third_party/shaderc/BUILD.external vendored
View File

@ -88,4 +88,5 @@ cc_binary(
":libshaderc",
":libshaderc_util",
],
visibility = ["//visibility:public"],
)

6
tools/bzl/glsl.bzl
View File

@ -3,7 +3,9 @@ def _glsl_binary(ctx):
binary = ctx.outputs.binary
compiler = ctx.executable._compiler
args = ["-V", "-o", binary.path] + [s.path for s in srcs]
main = srcs[0].path
args = [main, "-o", binary.path]
ctx.actions.run(
inputs=srcs,
@ -21,7 +23,7 @@ glsl_binary = rule(
allow_files=True,
),
"_compiler": attr.label(
default=Label("@glslang//:glslangValidator"),
default=Label("@shaderc//:glslc"),
allow_single_file=True,
executable=True,
cfg="host",