// Do not use if you suffer from epilepsy. Seriously. vec4 movInterlace(vec4 input1, vec4 input2) { if ((positionY + scaledTime) % 2 == 0 || (positionX + scaledTime) % 2 == 0) return input1; return input2; } //Why is time in there too? Why do I use both? Don't ask me, I wrote it a few weeks ago...