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#version 300 es
// Invert Colors Shader - OPTIMIZED
// Added: Optional luminance-preserving mode
precision highp float;
in vec2 v_texcoord;
uniform sampler2D tex;
out vec4 fragColor;
// Set true for "smart invert" that preserves relative brightness
const bool PRESERVE_LUMINANCE = false;
const vec3 LUMA = vec3(0.2126, 0.7152, 0.0722);
void main() {
vec4 color = texture(tex, v_texcoord);
vec3 inverted = 1.0 - color.rgb;
if (PRESERVE_LUMINANCE) {
// Adjust inverted colors to match original luminance
float origLuma = dot(color.rgb, LUMA);
float invLuma = dot(inverted, LUMA);
if (invLuma > 0.001) {
inverted *= origLuma / invLuma;
inverted = clamp(inverted, 0.0, 1.0);
}
}
fragColor = vec4(inverted, color.a);
}
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