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Channel Invert
runnable fragment
Complete GLSL fragment shader. Stronghold runs it directly when the browser can compile it.
Code
precision mediump float;
varying vec2 v_texCoord;
uniform sampler2D u_texture;
uniform vec2 u_resolution;
uniform int u_channel; // 0=all, 1=red only, 2=green only, 3=blue only
void main() {
vec4 c = texture2D(u_texture, v_texCoord);
if (u_channel == 0) {
c.rgb = 1.0 - c.rgb;
} else if (u_channel == 1) {
c.r = 1.0 - c.r;
} else if (u_channel == 2) {
c.g = 1.0 - c.g;
} else {
c.b = 1.0 - c.b;
}
gl_FragColor = c;
}