[vert.glsl]

#version 120

varying vec2 pass_TexCoord;

void main()
{
    gl_Position = gl_Vertex;
    pass_TexCoord = vec2(0.5, 0.5) + 0.5 * gl_Vertex.xy;
}

[frag.glsl]

#version 120

varying vec2 pass_TexCoord;

uniform sampler2D texture;
uniform vec2 screen_size;
uniform float time;
uniform vec4 copper;
uniform vec3 mask_color;

void main(void)
{
    vec2 p = pass_TexCoord;
    vec3 source = texture2D(texture, p).xyz;

    vec3 color = vec3(0.5);

    color.x += 0.5 * cos(p.y*float(screen_size.y / copper.w) + time);
    color.z += 0.5 * sin(p.y*float(screen_size.y / copper.w) + time);

    color *= copper.x + copper.y * cos(p.y * float(screen_size.x / copper.z));// - time);

    color.x = float(int(color.x * 8.0) * 32) / 256.0;
    color.y = float(int(color.y * 8.0) * 32) / 256.0;
    color.z = float(int(color.z * 8.0) * 32) / 256.0;

gl_FragColor = vec4((abs(source.x - mask_color.x) < 0.025 && abs(source.y - mask_color.y) < 0.025 && abs(source.z - mask_color.z) < 0.025) ? color : source, 1.0);
}