113 lines
3.6 KiB
GLSL
113 lines
3.6 KiB
GLSL
//------------------------------------------------------------------------------
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// Common color operations
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//------------------------------------------------------------------------------
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/**
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* Computes the luminance of the specified linear RGB color using the
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* luminance coefficients from Rec. 709.
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*
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* @public-api
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*/
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float luminance(const vec3 linear) {
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return dot(linear, vec3(0.2126, 0.7152, 0.0722));
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}
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/**
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* Computes the pre-exposed intensity using the specified intensity and exposure.
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* This function exists to force highp precision on the two parameters
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*/
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float computePreExposedIntensity(const highp float intensity, const highp float exposure) {
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return intensity * exposure;
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}
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void unpremultiply(inout vec4 color) {
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color.rgb /= max(color.a, FLT_EPS);
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}
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/**
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* Applies a full range YCbCr to sRGB conversion and returns an RGB color.
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*
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* @public-api
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*/
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vec3 ycbcrToRgb(float luminance, vec2 cbcr) {
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// Taken from https://developer.apple.com/documentation/arkit/arframe/2867984-capturedimage
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const mat4 ycbcrToRgbTransform = mat4(
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1.0000, 1.0000, 1.0000, 0.0000,
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0.0000, -0.3441, 1.7720, 0.0000,
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1.4020, -0.7141, 0.0000, 0.0000,
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-0.7010, 0.5291, -0.8860, 1.0000
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);
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return (ycbcrToRgbTransform * vec4(luminance, cbcr, 1.0)).rgb;
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}
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//------------------------------------------------------------------------------
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// Tone mapping operations
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//------------------------------------------------------------------------------
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/*
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* The input must be in the [0, 1] range.
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*/
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vec3 Inverse_Tonemap_Filmic(const vec3 x) {
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return (0.03 - 0.59 * x - sqrt(0.0009 + 1.3702 * x - 1.0127 * x * x)) / (-5.02 + 4.86 * x);
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}
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/**
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* Applies the inverse of the tone mapping operator to the specified HDR or LDR
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* sRGB (non-linear) color and returns a linear sRGB color. The inverse tone mapping
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* operator may be an approximation of the real inverse operation.
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*
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* @public-api
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*/
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vec3 inverseTonemapSRGB(vec3 color) {
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// sRGB input
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color = clamp(color, 0.0, 1.0);
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return Inverse_Tonemap_Filmic(pow(color, vec3(2.2)));
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}
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/**
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* Applies the inverse of the tone mapping operator to the specified HDR or LDR
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* linear RGB color and returns a linear RGB color. The inverse tone mapping operator
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* may be an approximation of the real inverse operation.
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*
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* @public-api
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*/
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vec3 inverseTonemap(vec3 linear) {
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// Linear input
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return Inverse_Tonemap_Filmic(clamp(linear, 0.0, 1.0));
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}
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//------------------------------------------------------------------------------
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// Common texture operations
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//------------------------------------------------------------------------------
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/**
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* Decodes the specified RGBM value to linear HDR RGB.
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*/
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vec3 decodeRGBM(vec4 c) {
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c.rgb *= (c.a * 16.0);
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return c.rgb * c.rgb;
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}
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//------------------------------------------------------------------------------
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// Common screen-space operations
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//------------------------------------------------------------------------------
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// returns the frag coord in the GL convention with (0, 0) at the bottom-left
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// resolution : width, height
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highp vec2 getFragCoord(const highp vec2 resolution) {
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#if defined(TARGET_METAL_ENVIRONMENT) || defined(TARGET_VULKAN_ENVIRONMENT) || defined(TARGET_WEBGPU_ENVIRONMENT)
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return vec2(gl_FragCoord.x, resolution.y - gl_FragCoord.y);
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#else
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return gl_FragCoord.xy;
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#endif
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}
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//------------------------------------------------------------------------------
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// Common debug
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//------------------------------------------------------------------------------
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vec3 heatmap(float v) {
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vec3 r = v * 2.1 - vec3(1.8, 1.14, 0.3);
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return 1.0 - r * r;
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}
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