varying vec2 v_vTexcoord;

// Do not edit these uniforms
uniform float time;
uniform sampler2D paletteTexture;
uniform vec2 paletteTexel;

uniform vec2 textureTexel;
uniform vec4 uv;

// Editable uniforms
uniform float index;
uniform float colors;
uniform float cycle;

uniform vec2 scroll;
uniform vec2 scale;

uniform vec3 oscillateX;
uniform vec3 oscillateY;
uniform vec3 oscillateSplit;

const float TWOPI = 6.28318530718;

void main()
{
    vec2 pos = v_vTexcoord;

    // Oscillate
    float moment = pos.y / textureTexel.y;

    // Horizontal
    pos.x += (oscillateX.x * textureTexel.x) * sin(TWOPI * (moment / oscillateX.y + time * oscillateX.z));

    // Split
    pos.x += (2. * floor(mod(moment, 2.0)) - 1.) * (oscillateSplit.x * textureTexel.x) * sin(TWOPI * (moment / oscillateSplit.y + time * oscillateSplit.z));

    // Vertical
    pos.y += (oscillateY.x * textureTexel.y) * sin(TWOPI * (moment / oscillateY.y + time * oscillateY.z));

    // Scroll
    pos *= scale;
    pos += scroll * textureTexel;

    // Wrap
    pos = vec2(mod(pos.x - uv.x, uv.z - uv.x) + uv.x, mod(pos.y - uv.y, uv.w - uv.y) + uv.y);

    // Palette
    vec4 color = texture2D(gm_BaseTexture, pos);
    float red = color.r * colors;
    red = mod(red + cycle, colors);
    vec2 palettePos = vec2((index + 0.5) * paletteTexel.x, (red + 0.5) * paletteTexel.y);

    // Render
    gl_FragColor = vec4(texture2D(paletteTexture, palettePos).rgb, color.a);
}