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https://github.com/italicsjenga/slang-shaders.git
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129 lines
4.3 KiB
Plaintext
129 lines
4.3 KiB
Plaintext
#version 450
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/**
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* FilmGrain version 1.0
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* by Christian Cann Schuldt Jensen ~ CeeJay.dk
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*
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* Computes a noise pattern and blends it with the image to create a film grain look.
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* ----------------------------------------------------------------------------------
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* Ported from https://github.com/crosire/reshade-shaders/blob/019921117c49beb4d1569af48f33cbb4e13033af/Shaders/FilmGrain.fx
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*/
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layout(push_constant) uniform Push
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{
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/* How visible the grain is. Higher is more visible. */
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float Intensity;
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/* Controls the variance of the Gaussian noise. Lower values look smoother. */
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float Variance;
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/* Affects the brightness of the noise. */
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float Mean;
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/* Higher Signal-to-Noise Ratio values give less grain to brighter pixels. 0 disables this feature. */
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float SignalToNoiseRatio;
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} params;
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#pragma parameter Intensity "Intensity" 0.50 0.00 1.00 0.01
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#pragma parameter Variance "Variance - lower is smoother" 0.40 0.00 1.00 0.01
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#pragma parameter Mean "Mean - affects brightness" 0.50 0.00 1.00 0.01
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#pragma parameter SignalToNoiseRatio "SNR - higher is less grain on brighter pixels." 6.00 0.00 16.00 1.00
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layout(std140, set = 0, binding = 0) uniform UBO
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{
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mat4 MVP;
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vec4 OutputSize;
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vec4 OriginalSize;
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vec4 SourceSize;
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uint FrameCount;
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} global;
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#pragma stage vertex
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layout(location = 0) in vec4 Position;
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layout(location = 1) in vec2 TexCoord;
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layout(location = 0) out vec2 vTexCoord;
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void main()
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{
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gl_Position = global.MVP * Position;
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vTexCoord = TexCoord;
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}
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#pragma stage fragment
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layout(location = 0) in vec2 vTexCoord;
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layout(location = 0) out vec4 FragColor;
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layout(set = 0, binding = 2) uniform sampler2D Source;
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#define PI 3.1415927
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vec3 FilmGrainPass(vec4 vpos, vec2 texcoord)
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{
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vec3 color = texture(Source, texcoord).rgb;
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//float inv_luma = dot(color, vec3(-0.2126, -0.7152, -0.0722)) + 1.0;
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float inv_luma = dot(color, vec3(-1.0/3.0, -1.0/3.0, -1.0/3.0)) + 1.0; //Calculate the inverted luma so it can be used later to control the variance of the grain
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/*---------------------.
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| :: Generate Grain :: |
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'---------------------*/
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/* We use slang's FrameCount uniform variable instead of ReShade's Timer */
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/* We assume frame rate is 60 */
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float t = global.FrameCount * 16.667 * 0.0022337;
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//PRNG 2D - create two uniform noise values and save one DP2ADD
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float seed = dot(texcoord, vec2(12.9898, 78.233));// + t;
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float sine = sin(seed);
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float cosine = cos(seed);
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float uniform_noise1 = fract(sine * 43758.5453 + t); //I just salt with t because I can
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float uniform_noise2 = fract(cosine * 53758.5453 - t); // and it doesn't cost any extra ASM
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//Get settings
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float stn = params.SignalToNoiseRatio < 1.0 ? 1.0 : pow(abs(inv_luma), params.SignalToNoiseRatio); // Signal to noise feature - Brighter pixels get less noise.
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float variance = (params.Variance*params.Variance) * stn;
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float mean = params.Mean;
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//Box-Muller transform
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uniform_noise1 = (uniform_noise1 < 0.0001) ? 0.0001 : uniform_noise1; //fix log(0)
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float r = sqrt(-log(uniform_noise1));
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r = (uniform_noise1 < 0.0001) ? PI : r; //fix log(0) - PI happened to be the right answer for uniform_noise == ~ 0.0000517.. Close enough and we can reuse a constant.
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float theta = (2.0 * PI) * uniform_noise2;
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float gauss_noise1 = variance * r * cos(theta) + mean;
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//float gauss_noise2 = variance * r * sin(theta) + mean; //we can get two gaussians out of it :)
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//gauss_noise1 = (ddx(gauss_noise1) - ddy(gauss_noise1)) * 0.50 + gauss_noise2;
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//Calculate how big the shift should be
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//float grain = mix(1.0 - params.Intensity, 1.0 + params.Intensity, gauss_noise1);
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float grain = mix(1.0 + params.Intensity, 1.0 - params.Intensity, gauss_noise1);
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//float grain2 = (2.0 * params.Intensity) * gauss_noise1 + (1.0 - params.Intensity);
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//Apply grain
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color = color * grain;
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//color = (grain-1.0) *2.0 + 0.5;
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//color = mix(color,colorInput.rgb,sqrt(luma));
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/*-------------------------.
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| :: Debugging features :: |
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'-------------------------*/
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//color.rgb = fract(gauss_noise1).xxx; //show the noise
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//color.rgb = (gauss_noise1 > 0.999) ? vec3(1.0,1.0,0.0) : 0.0 ; //does it reach 1.0?
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return color.rgb;
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}
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void main()
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{
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FragColor.rgb = FilmGrainPass(FragColor, vTexCoord);
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}
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