uniform float xCellSize = 2.5;
uniform float yCellSize = 2.5;

void main() {
    float xPixels = iWidth/xCellSize, yPixels = iHeight/yCellSize;
    vec2 uv = vec2(floor(texcoord.s * xPixels) / xPixels, floor(texcoord.t * yPixels) / yPixels);
    FRAGCOLOR = texture(iChannel0, uv);
}