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uniform sampler2D strokeColor;
uniform sampler2D strokeDepth;
uniform vec4 low_color;
uniform vec4 high_color;
uniform int mode;
uniform float factor;
out vec4 FragColor;
#define MODE_GRAYSCALE 0
#define MODE_SEPIA 1
#define MODE_BITONE 2
#define MODE_CUSTOM 3
#define MODE_TRANSPARENT 4
float get_luminance(vec4 color)
{
float lum = (color.r * 0.2126) + (color.g * 0.7152) + (color.b * 0.723);
return lum;
}
void main()
{
ivec2 uv = ivec2(gl_FragCoord.xy);
float stroke_depth = texelFetch(strokeDepth, uv.xy, 0).r;
vec4 src_pixel= texelFetch(strokeColor, uv.xy, 0);
float luminance = get_luminance(src_pixel);
vec4 outcolor;
/* is transparent */
if (src_pixel.a == 0.0f) {
discard;
}
switch(mode) {
case MODE_GRAYSCALE:
{
outcolor = vec4(luminance, luminance, luminance, src_pixel.a);
break;
}
case MODE_SEPIA:
{
float Red = (src_pixel.r * 0.393) + (src_pixel.g * 0.769) + (src_pixel.b * 0.189);
float Green = (src_pixel.r * 0.349) + (src_pixel.g * 0.686) + (src_pixel.b * 0.168);
float Blue = (src_pixel.r * 0.272) + (src_pixel.g * 0.534) + (src_pixel.b * 0.131);
outcolor = vec4(Red, Green, Blue, src_pixel.a);
break;
}
case MODE_BITONE:
{
if (luminance <= factor) {
outcolor = low_color;
}
else {
outcolor = high_color;
}
break;
}
case MODE_CUSTOM:
{
/* if below umbral, force custom color */
if (luminance <= factor) {
outcolor = low_color;
}
else {
outcolor = vec4(luminance * low_color.r, luminance * low_color.b, luminance * low_color.b, src_pixel.a);
}
break;
}
case MODE_TRANSPARENT:
{
outcolor = vec4(src_pixel.rgb, src_pixel.a * factor);
break;
}
default:
{
outcolor = src_pixel;
}
}
gl_FragDepth = stroke_depth;
FragColor = outcolor;
}
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