 	cudaTextureObject_t vtxPos,
 	cudaTextureObject_t vtxNml)
 {
-	const auto ix = blockIdx.x * blockDim.x + threadIdx.x;
-	const auto iy = blockIdx.y * blockDim.y + threadIdx.y;
-	//int ix = 136;
-	//int iy = 512 - 388;
+	auto ix = blockIdx.x * blockDim.x + threadIdx.x;
+	auto iy = blockIdx.y * blockDim.y + threadIdx.y;
+	//int ix = 134;
+	//int iy = 512 - 374;
 
 	if (ix >= width && iy >= height) {
 		return;

		stride, jitter,
		hitPixel);

	int x = (int)hitPixel.x;
	int y = (int)hitPixel.y;

	isIntersect = isIntersect && (0 <= x && x < width && 0 <= y && y < height);

	int objid = -1;
	int primid = -1;

	float stepDir = delta.x < 0.0f ? -1.0f : 0.0f;
	stepDir = delta.x > 0.0f ? 1.0f : delta.x;

#if 0
	printf("delta %f, %f\n", delta.x, delta.y);
	printf("stepDir %f\n", stepDir);
	printf("permute %s\n", permute ? "true" : "false");
#endif

	float invdx = stepDir / delta.x;

	// Track the derivatives of Q and k.
