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fgdata/Shaders/HDR/bloom_upsample.frag
Fernando García Liñán f53a170539 HDR: Better bloom effect
We also now pre-expose our lighting before writing to the HDR buffers.
This solves some precision issues and prevents the Sun from producing
infinite values.
2023-04-13 00:30:02 +02:00

52 lines
1.6 KiB
GLSL

/*
* Bloom - upsampling step
* "Next Generation Post Processing in Call of Duty Advanced Warfare"
* ACM Siggraph (2014)
* Based on the implementation by Alexander Christensen
* https://learnopengl.com/Guest-Articles/2022/Phys.-Based-Bloom
*/
#version 330 core
layout(location = 0) out vec3 fragColor;
in vec2 texcoord;
uniform sampler2D tex;
uniform float filter_radius;
void main()
{
// The filter kernel is applied with a radius, specified in texture
// coordinates, so that the radius will vary across mip resolutions.
float x = filter_radius;
float y = filter_radius;
// Take 9 samples around current texel:
// a - b - c
// d - e - f
// g - h - i
// === ('e' is the current texel) ===
vec3 a = texture(tex, vec2(texcoord.x - x, texcoord.y + y)).rgb;
vec3 b = texture(tex, vec2(texcoord.x, texcoord.y + y)).rgb;
vec3 c = texture(tex, vec2(texcoord.x + x, texcoord.y + y)).rgb;
vec3 d = texture(tex, vec2(texcoord.x - x, texcoord.y)).rgb;
vec3 e = texture(tex, vec2(texcoord.x, texcoord.y)).rgb;
vec3 f = texture(tex, vec2(texcoord.x + x, texcoord.y)).rgb;
vec3 g = texture(tex, vec2(texcoord.x - x, texcoord.y - y)).rgb;
vec3 h = texture(tex, vec2(texcoord.x, texcoord.y - y)).rgb;
vec3 i = texture(tex, vec2(texcoord.x + x, texcoord.y - y)).rgb;
// Apply weighted distribution, by using a 3x3 tent filter:
// 1 | 1 2 1 |
// -- * | 2 4 2 |
// 16 | 1 2 1 |
vec3 upsample = e * 4.0;
upsample += (b+d+f+h) * 2.0;
upsample += (a+c+g+i);
upsample /= 16.0;
fragColor = upsample;
}