test.js

this.gpuDraw = this.gpu
      .createKernel(function(buffer, sprite, x, y, w, h, bufferWidth) {
        var subBufferWidth = w * 4;
        var cy = Math.floor(this.thread.x / bufferWidth);
        var cx = this.thread.x % bufferWidth;
        var dx = x - cx;
        var dy = y - cy;
        var dz = this.thread.x % 4;
        if (dx > 0 && dx < w && dy > 0 && dy < h) {
            //console.log(dx, dy, dz); //these are logging fine btw
            return sprite[0][0][0];
        } else {
          return buffer[this.thread.x];
        }
      })
      .setOutput([this.smallWidth * this.smallHeight * 4]);

this.buffer = this.gpuDraw(
        bufferCopy,
        entity.sprite,
        entity.x,
        entity.y,
        entity.w,
        entity.h,
        this.bufferWidth
      );