38 lines
1.3 KiB
Text
38 lines
1.3 KiB
Text
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precision mediump float;
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out vec4 color;
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in vec2 screen_pos;
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in vec2 uvs;
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uniform sampler2D pdf_texture;
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uniform float contrast;
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//http://gamedev.stackexchange.com/questions/59797/glsl-shader-change-hue-saturation-brightness
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vec3 rgb2hsv(vec3 c)
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{
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vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
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vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
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vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
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float d = q.x - min(q.w, q.y);
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float e = 1.0e-10;
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return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
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}
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vec3 hsv2rgb(vec3 c)
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{
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vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
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vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
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return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
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}
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void main(){
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vec3 tempcolor = texture(pdf_texture, uvs).rgb;
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vec3 inv = (0.5-tempcolor)*contrast+0.5; //Invert colors and shift colors from range 0.0 - 1.0 to -0.5 - 0.5, apply contrast and shift back to 0.0 - 1.0. This way contrast applies on both whites and blacks
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vec3 hsvcolor = rgb2hsv(inv); //transform to hsv
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float new_hue = mod(hsvcolor.r + 0.5, 1.0); // shift hue 180 degrees to compensate hue shift from inverting colors
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vec3 newcolor = hsv2rgb(vec3(new_hue,hsvcolor.gb));
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color = vec4(newcolor, 1.0);
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}
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