blender/intern/cycles/kernel/geom/geom_triangle_intersect.h

			/*
 * Copyright 2014, Blender Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/* Triangle/Ray intersections.
 *
 * For BVH ray intersection we use a precomputed triangle storage to accelerate
 * intersection at the cost of more memory usage.
 */

CCL_NAMESPACE_BEGIN

ccl_device_inline bool triangle_intersect(KernelGlobals *kg,
                                          Intersection *isect,
                                          float3 P,
                                          float3 dir,
                                          uint visibility,
                                          int object,
                                          int prim_addr)
{
	const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, prim_addr);
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
	const ssef *ssef_verts = (ssef*)&kg->__prim_tri_verts.data[tri_vindex];
#else
	const float4 tri_a = kernel_tex_fetch(__prim_tri_verts, tri_vindex+0),
	             tri_b = kernel_tex_fetch(__prim_tri_verts, tri_vindex+1),
	             tri_c = kernel_tex_fetch(__prim_tri_verts, tri_vindex+2);
#endif
	float t, u, v;
	if(ray_triangle_intersect(P,
	                          dir,
	                          isect->t,
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
	                          ssef_verts,
#else
	                          float4_to_float3(tri_a),
	                          float4_to_float3(tri_b),
	                          float4_to_float3(tri_c),
#endif
	                          &u, &v, &t))
	{
#ifdef __VISIBILITY_FLAG__
		/* Visibility flag test. we do it here under the assumption
		 * that most triangles are culled by node flags.
		 */
		if(kernel_tex_fetch(__prim_visibility, prim_addr) & visibility)
#endif
		{
			isect->prim = prim_addr;
			isect->object = object;
			isect->type = PRIMITIVE_TRIANGLE;
			isect->u = u;
			isect->v = v;
			isect->t = t;
			return true;
		}
	}
	return false;
}

#ifdef __KERNEL_AVX2__
#define	cross256(A,B, C,D) _mm256_fmsub_ps(A,B, _mm256_mul_ps(C,D))
ccl_device_inline int ray_triangle_intersect8(
            KernelGlobals *kg,
            float3 ray_P,
            float3 ray_dir,
            Intersection **isect,
            uint visibility,
            int object,
            __m256 *triA,
            __m256 *triB,
            __m256 *triC,
            int prim_addr,
            int prim_num,
            uint *num_hits,
            uint max_hits,
            int *num_hits_in_instance,
            float isect_t)
{

	const unsigned char prim_num_mask = (1 << prim_num) - 1;

	const __m256i zero256 = _mm256_setzero_si256();

	const __m256 Px256 = _mm256_set1_ps(ray_P.x);
	const __m256 Py256 = _mm256_set1_ps(ray_P.y);
	const __m256 Pz256 = _mm256_set1_ps(ray_P.z);

	const __m256 dirx256 = _mm256_set1_ps(ray_dir.x);
	const __m256 diry256 = _mm256_set1_ps(ray_dir.y);
	const __m256 dirz256 = _mm256_set1_ps(ray_dir.z);

	/* Calculate vertices relative to ray origin. */
	__m256 v0_x_256 = _mm256_sub_ps(triC[0], Px256);
	__m256 v0_y_256 = _mm256_sub_ps(triC[1], Py256);
	__m256 v0_z_256 = _mm256_sub_ps(triC[2], Pz256);

	__m256 v1_x_256 = _mm256_sub_ps(triA[0], Px256);
	__m256 v1_y_256 = _mm256_sub_ps(triA[1], Py256);
	__m256 v1_z_256 = _mm256_sub_ps(triA[2], Pz256);

	__m256 v2_x_256 = _mm256_sub_ps(triB[0], Px256);
	__m256 v2_y_256 = _mm256_sub_ps(triB[1], Py256);
	__m256 v2_z_256 = _mm256_sub_ps(triB[2], Pz256);

	__m256 v0_v1_x_256 = _mm256_add_ps(v0_x_256, v1_x_256);
	__m256 v0_v1_y_256 = _mm256_add_ps(v0_y_256, v1_y_256);
	__m256 v0_v1_z_256 = _mm256_add_ps(v0_z_256, v1_z_256);

	__m256 v0_v2_x_256 = _mm256_add_ps(v0_x_256, v2_x_256);
	__m256 v0_v2_y_256 = _mm256_add_ps(v0_y_256, v2_y_256);
	__m256 v0_v2_z_256 = _mm256_add_ps(v0_z_256, v2_z_256);

	__m256 v1_v2_x_256 = _mm256_add_ps(v1_x_256, v2_x_256);
	__m256 v1_v2_y_256 = _mm256_add_ps(v1_y_256, v2_y_256);
	__m256 v1_v2_z_256 = _mm256_add_ps(v1_z_256, v2_z_256);

	/* Calculate triangle edges. */
	__m256 e0_x_256 = _mm256_sub_ps(v2_x_256, v0_x_256);
	__m256 e0_y_256 = _mm256_sub_ps(v2_y_256, v0_y_256);
	__m256 e0_z_256 = _mm256_sub_ps(v2_z_256, v0_z_256);

	__m256 e1_x_256 = _mm256_sub_ps(v0_x_256, v1_x_256);
	__m256 e1_y_256 = _mm256_sub_ps(v0_y_256, v1_y_256);
	__m256 e1_z_256 = _mm256_sub_ps(v0_z_256, v1_z_256);

	__m256 e2_x_256 = _mm256_sub_ps(v1_x_256, v2_x_256);
	__m256 e2_y_256 = _mm256_sub_ps(v1_y_256, v2_y_256);
	__m256 e2_z_256 = _mm256_sub_ps(v1_z_256, v2_z_256);

	/* Perform edge tests. */
	/* cross (AyBz - AzBy, AzBx -AxBz,  AxBy - AyBx) */
	__m256 U_x_256 = cross256(v0_v2_y_256, e0_z_256, v0_v2_z_256, e0_y_256);
	__m256 U_y_256 = cross256(v0_v2_z_256, e0_x_256, v0_v2_x_256, e0_z_256);
	__m256 U_z_256 = cross256(v0_v2_x_256, e0_y_256, v0_v2_y_256, e0_x_256);
	/* vertical dot */
	__m256 U_256 = _mm256_mul_ps(U_x_256, dirx256);
	U_256 = _mm256_fmadd_ps(U_y_256, diry256, U_256);
	U_256 = _mm256_fmadd_ps(U_z_256, dirz256, U_256);

	__m256 V_x_256 = cross256(v0_v1_y_256, e1_z_256, v0_v1_z_256, e1_y_256);
	__m256 V_y_256 = cross256(v0_v1_z_256, e1_x_256, v0_v1_x_256, e1_z_256);
	__m256 V_z_256 = cross256(v0_v1_x_256, e1_y_256, v0_v1_y_256, e1_x_256);
	/* vertical dot */
	__m256 V_256 = _mm256_mul_ps(V_x_256, dirx256);
	V_256 = _mm256_fmadd_ps(V_y_256, diry256, V_256);
	V_256 = _mm256_fmadd_ps(V_z_256, dirz256, V_256);

	__m256 W_x_256 = cross256(v1_v2_y_256, e2_z_256, v1_v2_z_256, e2_y_256);
	__m256 W_y_256 = cross256(v1_v2_z_256, e2_x_256, v1_v2_x_256, e2_z_256);
	__m256 W_z_256 = cross256(v1_v2_x_256, e2_y_256, v1_v2_y_256, e2_x_256);
	/* vertical dot */
	__m256 W_256 = _mm256_mul_ps(W_x_256, dirx256);
	W_256 = _mm256_fmadd_ps(W_y_256, diry256,W_256);
	W_256 = _mm256_fmadd_ps(W_z_256, dirz256,W_256);

	__m256i U_256_1 = _mm256_srli_epi32(_mm256_castps_si256(U_256), 31);
	__m256i V_256_1 = _mm256_srli_epi32(_mm256_castps_si256(V_256), 31);
	__m256i W_256_1 = _mm256_srli_epi32(_mm256_castps_si256(W_256), 31);
	__m256i UVW_256_1 = _mm256_add_epi32(_mm256_add_epi32(U_256_1, V_256_1), W_256_1);

	const __m256i one256 = _mm256_set1_epi32(1);
	const __m256i two256 = _mm256_set1_epi32(2);

	__m256i mask_minmaxUVW_256 = _mm256_or_si256(
	        _mm256_cmpeq_epi32(one256, UVW_256_1),
	        _mm256_cmpeq_epi32(two256, UVW_256_1));

	unsigned char mask_minmaxUVW_pos = _mm256_movemask_ps(_mm256_castsi256_ps(mask_minmaxUVW_256));
	if((mask_minmaxUVW_pos & prim_num_mask) == prim_num_mask) { //all bits set
		return false;
	}

	/* Calculate geometry normal and denominator. */
	__m256 Ng1_x_256 = cross256(e1_y_256, e0_z_256, e1_z_256, e0_y_256);
	__m256 Ng1_y_256 = cross256(e1_z_256, e0_x_256, e1_x_256, e0_z_256);
	__m256 Ng1_z_256 = cross256(e1_x_256, e0_y_256, e1_y_256, e0_x_256);

	Ng1_x_256 = _mm256_add_ps(Ng1_x_256, Ng1_x_256);
	Ng1_y_256 = _mm256_add_ps(Ng1_y_256, Ng1_y_256);
	Ng1_z_256 = _mm256_add_ps(Ng1_z_256, Ng1_z_256);

	/* vertical dot */
	__m256 den_256 = _mm256_mul_ps(Ng1_x_256, dirx256);
	den_256 = _mm256_fmadd_ps(Ng1_y_256, diry256,den_256);
	den_256 = _mm256_fmadd_ps(Ng1_z_256, dirz256,den_256);

	/* Perform depth test. */
	__m256 T_256 = _mm256_mul_ps(Ng1_x_256, v0_x_256);
	T_256 = _mm256_fmadd_ps(Ng1_y_256, v0_y_256,T_256);
	T_256 = _mm256_fmadd_ps(Ng1_z_256, v0_z_256,T_256);

	const __m256i c0x80000000 = _mm256_set1_epi32(0x80000000);
	__m256i sign_den_256 = _mm256_and_si256(_mm256_castps_si256(den_256), c0x80000000);

	__m256 sign_T_256 = _mm256_castsi256_ps(_mm256_xor_si256(_mm256_castps_si256(T_256), sign_den_256));

	unsigned char mask_sign_T = _mm256_movemask_ps(sign_T_256);
	if(((mask_minmaxUVW_pos | mask_sign_T) & prim_num_mask) == prim_num_mask) {
		return false;
	}

	__m256 xor_signmask_256 = _mm256_castsi256_ps(_mm256_xor_si256(_mm256_castps_si256(den_256), sign_den_256));

	ccl_align(32) float den8[8], U8[8], V8[8], T8[8], sign_T8[8], xor_signmask8[8];
	ccl_align(32) unsigned int mask_minmaxUVW8[8];

	if(visibility == PATH_RAY_SHADOW_OPAQUE) {
		__m256i mask_final_256 = _mm256_cmpeq_epi32(mask_minmaxUVW_256, zero256);
		__m256i maskden256 = _mm256_cmpeq_epi32(_mm256_castps_si256(den_256), zero256);
		__m256i mask0 = _mm256_cmpgt_epi32(zero256, _mm256_castps_si256(sign_T_256));
		__m256 rayt_256 = _mm256_set1_ps((*isect)->t);
		__m256i mask1 = _mm256_cmpgt_epi32(_mm256_castps_si256(sign_T_256),
			_mm256_castps_si256(
				_mm256_mul_ps(_mm256_castsi256_ps(_mm256_xor_si256(_mm256_castps_si256(den_256), sign_den_256)), rayt_256)
			)
		);
		mask0 = _mm256_or_si256(mask1, mask0);
		mask_final_256 = _mm256_andnot_si256(mask0, mask_final_256); //(~mask_minmaxUVW_pos) &(~mask)
		mask_final_256 = _mm256_andnot_si256(maskden256, mask_final_256); //(~mask_minmaxUVW_pos) &(~mask) & (~maskden)
		unsigned char mask_final = _mm256_movemask_ps(_mm256_castsi256_ps(mask_final_256));
		if((mask_final & prim_num_mask) == 0) {
			return false;
		}
		const int i = __bsf(mask_final);
		__m256 inv_den_256 = _mm256_rcp_ps(den_256);
		U_256 = _mm256_mul_ps(U_256, inv_den_256);
		V_256 = _mm256_mul_ps(V_256, inv_den_256);
		T_256 = _mm256_mul_ps(T_256, inv_den_256);
		_mm256_store_ps(U8, U_256);
		_mm256_store_ps(V8, V_256);
		_mm256_store_ps(T8, T_256);
		/* NOTE: Here we assume visibility for all triangles in the node is
		 * the same. */
		(*isect)->u = U8[i];
		(*isect)->v = V8[i];
		(*isect)->t = T8[i];
		(*isect)->prim = (prim_addr + i);
		(*isect)->object = object;
		(*isect)->type = PRIMITIVE_TRIANGLE;
		return true;
	}
	else {
		_mm256_store_ps(den8, den_256);
		_mm256_store_ps(U8, U_256);
		_mm256_store_ps(V8, V_256);
		_mm256_store_ps(T8, T_256);

		_mm256_store_ps(sign_T8, sign_T_256);
		_mm256_store_ps(xor_signmask8, xor_signmask_256);
		_mm256_store_si256((__m256i*)mask_minmaxUVW8, mask_minmaxUVW_256);

		int ret = false;

		if(visibility == PATH_RAY_SHADOW) {
			for(int i = 0; i < prim_num; i++) {
				if(mask_minmaxUVW8[i]) {
					continue;
				}
#ifdef __VISIBILITY_FLAG__
				if((kernel_tex_fetch(__prim_visibility, (prim_addr + i)) & visibility) == 0) {
					continue;
				}
#endif
				if((sign_T8[i] < 0.0f) ||
				   (sign_T8[i] > (*isect)->t * xor_signmask8[i]))
				{
					continue;
				}
				if(!den8[i]) {
					continue;
				}
				const float inv_den = 1.0f / den8[i];
				(*isect)->u = U8[i] * inv_den;
				(*isect)->v = V8[i] * inv_den;
				(*isect)->t = T8[i] * inv_den;
				(*isect)->prim = (prim_addr + i);
				(*isect)->object = object;
				(*isect)->type = PRIMITIVE_TRIANGLE;
				const int prim = kernel_tex_fetch(__prim_index, (*isect)->prim);
				int shader = 0;
#ifdef __HAIR__
				if(kernel_tex_fetch(__prim_type, (*isect)->prim) & PRIMITIVE_ALL_TRIANGLE)
#endif
				{
					shader = kernel_tex_fetch(__tri_shader, prim);
				}
#ifdef __HAIR__
				else {
					float4 str = kernel_tex_fetch(__curves, prim);
					shader = __float_as_int(str.z);
				}
#endif
				const int flag = kernel_tex_fetch(__shaders, (shader & SHADER_MASK)).flags;
				/* If no transparent shadows, all light is blocked. */
				if(!(flag & SD_HAS_TRANSPARENT_SHADOW)) {
					return 2;
				}
				/* If maximum number of hits reached, block all light. */
				else if(num_hits == NULL || *num_hits == max_hits) {
					return 2;
				}
				/* Move on to next entry in intersections array. */
				ret = true;
				(*isect)++;
				(*num_hits)++;
				(*num_hits_in_instance)++;
				(*isect)->t = isect_t;
			}
		}
		else {
			for(int i = 0; i < prim_num; i++) {
				if(mask_minmaxUVW8[i]) {
					continue;
				}
#ifdef __VISIBILITY_FLAG__
				if((kernel_tex_fetch(__prim_visibility, (prim_addr + i)) & visibility) == 0) {
					continue;
				}
#endif
				if((sign_T8[i] < 0.0f) ||
				   (sign_T8[i] > (*isect)->t * xor_signmask8[i]))
				{
					continue;
				}
				if(!den8[i]) {
					continue;
				}
				const float inv_den = 1.0f / den8[i];
				(*isect)->u = U8[i] * inv_den;
				(*isect)->v = V8[i] * inv_den;
				(*isect)->t = T8[i] * inv_den;
				(*isect)->prim = (prim_addr + i);
				(*isect)->object = object;
				(*isect)->type = PRIMITIVE_TRIANGLE;
				ret = true;
			}
		}
		return ret;
	}
}

ccl_device_inline int triangle_intersect8(
        KernelGlobals *kg,
        Intersection **isect,
        float3 P,
        float3 dir,
        uint visibility,
        int object,
        int prim_addr,
        int prim_num,
        uint *num_hits,
        uint max_hits,
        int *num_hits_in_instance,
        float isect_t)
 {
	__m128 tri_a[8], tri_b[8], tri_c[8];
	__m256  tritmp[12], tri[12];
	__m256  triA[3], triB[3], triC[3];

	int i, r;

	uint tri_vindex = kernel_tex_fetch(__prim_tri_index, prim_addr);
	for(i = 0; i < prim_num; i++) {
		tri_a[i] = *(__m128*)&kg->__prim_tri_verts.data[tri_vindex++];
		tri_b[i] = *(__m128*)&kg->__prim_tri_verts.data[tri_vindex++];
		tri_c[i] = *(__m128*)&kg->__prim_tri_verts.data[tri_vindex++];
	 }
	//create 9 or  12 placeholders
	tri[0] = _mm256_castps128_ps256(tri_a[0]);    //_mm256_zextps128_ps256
	tri[1] = _mm256_castps128_ps256(tri_b[0]);//_mm256_zextps128_ps256
	tri[2] = _mm256_castps128_ps256(tri_c[0]);//_mm256_zextps128_ps256

	tri[3] = _mm256_castps128_ps256(tri_a[1]);    //_mm256_zextps128_ps256
	tri[4] = _mm256_castps128_ps256(tri_b[1]);//_mm256_zextps128_ps256
	tri[5] = _mm256_castps128_ps256(tri_c[1]);//_mm256_zextps128_ps256

	tri[6] = _mm256_castps128_ps256(tri_a[2]);    //_mm256_zextps128_ps256
	tri[7] = _mm256_castps128_ps256(tri_b[2]);//_mm256_zextps128_ps256
	tri[8] = _mm256_castps128_ps256(tri_c[2]);//_mm256_zextps128_ps256

	if(prim_num > 3) {
		tri[9] =  _mm256_castps128_ps256(tri_a[3]);    //_mm256_zextps128_ps256
		tri[10] = _mm256_castps128_ps256(tri_b[3]);//_mm256_zextps128_ps256
		tri[11] = _mm256_castps128_ps256(tri_c[3]);//_mm256_zextps128_ps256
	}

	for(i = 4, r = 0; i < prim_num; i ++, r += 3) {
		tri[r] =     _mm256_insertf128_ps(tri[r] , tri_a[i], 1);
		tri[r + 1] = _mm256_insertf128_ps(tri[r + 1], tri_b[i], 1);
		tri[r + 2] = _mm256_insertf128_ps(tri[r + 2], tri_c[i], 1);
	 }

	//------------------------------------------------
	//0!  Xa0 Ya0 Za0 1 Xa4 Ya4 Za4  1
	//1!  Xb0 Yb0 Zb0 1 Xb4 Yb4 Zb4 1
	//2!  Xc0 Yc0 Zc0 1 Xc4 Yc4 Zc4 1

	//3!  Xa1 Ya1 Za1 1 Xa5 Ya5 Za5 1
	//4!  Xb1 Yb1 Zb1 1 Xb5 Yb5 Zb5  1
	//5!  Xc1 Yc1 Zc1 1 Xc5 Yc5 Zc5 1

	//6!  Xa2 Ya2 Za2 1 Xa6 Ya6 Za6 1
	//7!  Xb2 Yb2 Zb2 1 Xb6 Yb6 Zb6  1
	//8!  Xc2 Yc2 Zc2 1 Xc6 Yc6 Zc6 1

	//9!  Xa3 Ya3 Za3 1 Xa7 Ya7 Za7  1
	//10! Xb3 Yb3 Zb3 1 Xb7 Yb7 Zb7  1
	//11! Xc3 Yc3 Zc3 1 Xc7 Yc7 Zc7  1

	//"transpose"
	tritmp[0] = _mm256_unpacklo_ps(tri[0], tri[3]);   //0!  Xa0 Xa1 Ya0 Ya1 Xa4 Xa5 Ya4 Ya5
	tritmp[1] = _mm256_unpackhi_ps(tri[0], tri[3]);   //1!  Za0 Za1 1   1   Za4 Za5  1   1

	tritmp[2] = _mm256_unpacklo_ps(tri[6], tri[9]);   //2!  Xa2 Xa3 Ya2 Ya3 Xa6 Xa7 Ya6 Ya7
	tritmp[3] = _mm256_unpackhi_ps(tri[6], tri[9]);   //3!  Za2 Za3  1   1  Za6 Za7  1   1

	tritmp[4] = _mm256_unpacklo_ps(tri[1], tri[4]);   //4!  Xb0 Xb1 Yb0 Yb1 Xb4 Xb5 Yb4 Yb5
	tritmp[5] = _mm256_unpackhi_ps(tri[1], tri[4]);   //5!  Zb0 Zb1  1  1   Zb4 Zb5  1   1

	tritmp[6] = _mm256_unpacklo_ps(tri[7], tri[10]);  //6!  Xb2 Xb3 Yb2 Yb3 Xb6 Xb7 Yb6 Yb7
	tritmp[7] = _mm256_unpackhi_ps(tri[7], tri[10]);  //7!  Zb2 Zb3  1    1 Zb6 Zb7  1   1

	tritmp[8] = _mm256_unpacklo_ps(tri[2], tri[5]);   //8!  Xc0 Xc1 Yc0 Yc1 Xc4 Xc5 Yc4 Yc5
	tritmp[9] = _mm256_unpackhi_ps(tri[2], tri[5]);   //9!  Zc0 Zc1  1   1  Zc4 Zc5  1   1

	tritmp[10] = _mm256_unpacklo_ps(tri[8], tri[11]); //10! Xc2 Xc3 Yc2 Yc3 Xc6 Xc7 Yc6 Yc7
	tritmp[11] = _mm256_unpackhi_ps(tri[8], tri[11]); //11! Zc2 Zc3  1   1  Zc6 Zc7  1   1

				/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
	triA[0] = _mm256_castpd_ps(_mm256_unpacklo_pd(_mm256_castps_pd(tritmp[0]), _mm256_castps_pd(tritmp[2]))); 	//  Xa0 Xa1 Xa2 Xa3 Xa4 Xa5 Xa6 Xa7
	triA[1] = _mm256_castpd_ps(_mm256_unpackhi_pd(_mm256_castps_pd(tritmp[0]), _mm256_castps_pd(tritmp[2])));   //  Ya0 Ya1 Ya2 Ya3 Ya4 Ya5 Ya6 Ya7
	triA[2] = _mm256_castpd_ps(_mm256_unpacklo_pd(_mm256_castps_pd(tritmp[1]), _mm256_castps_pd(tritmp[3])));   //  Za0 Za1 Za2 Za3 Za4 Za5 Za6 Za7

	triB[0] = _mm256_castpd_ps(_mm256_unpacklo_pd(_mm256_castps_pd(tritmp[4]), _mm256_castps_pd(tritmp[6]))); 	//  Xb0 Xb1  Xb2 Xb3 Xb4 Xb5 Xb5 Xb7
	triB[1] = _mm256_castpd_ps(_mm256_unpackhi_pd(_mm256_castps_pd(tritmp[4]), _mm256_castps_pd(tritmp[6])));   //  Yb0 Yb1  Yb2 Yb3 Yb4 Yb5 Yb5 Yb7
	triB[2] = _mm256_castpd_ps(_mm256_unpacklo_pd(_mm256_castps_pd(tritmp[5]), _mm256_castps_pd(tritmp[7]))); //    Zb0 Zb1  Zb2 Zb3 Zb4 Zb5 Zb5 Zb7

	triC[0] = _mm256_castpd_ps(_mm256_unpacklo_pd(_mm256_castps_pd(tritmp[8]), _mm256_castps_pd(tritmp[10])));     //Xc0 Xc1 Xc2 Xc3 Xc4 Xc5 Xc6 Xc7
	triC[1] = _mm256_castpd_ps(_mm256_unpackhi_pd(_mm256_castps_pd(tritmp[8]), _mm256_castps_pd(tritmp[10])));     //Yc0 Yc1 Yc2 Yc3 Yc4 Yc5 Yc6 Yc7
	triC[2] = _mm256_castpd_ps(_mm256_unpacklo_pd(_mm256_castps_pd(tritmp[9]), _mm256_castps_pd(tritmp[11])));     //Zc0 Zc1 Zc2 Zc3 Zc4 Zc5 Zc6 Zc7

			  /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/

	int result = ray_triangle_intersect8(kg, P,
	                                     dir,
	                                     isect,
	                                     visibility, object,
	                                     triA,
	                                     triB,
	                                     triC,
	                                     prim_addr,
	                                     prim_num,
	                                     num_hits,
	                                     max_hits,
	                                     num_hits_in_instance,
	                                     isect_t);
	return result;
}

#endif  /* __KERNEL_AVX2__ */

/* Special ray intersection routines for subsurface scattering. In that case we
 * only want to intersect with primitives in the same object, and if case of
 * multiple hits we pick a single random primitive as the intersection point.
 * Returns whether traversal should be stopped.
 */

#ifdef __BVH_LOCAL__
ccl_device_inline bool triangle_intersect_local(
        KernelGlobals *kg,
        LocalIntersection *local_isect,
        float3 P,
        float3 dir,
        int object,
        int local_object,
        int prim_addr,
        float tmax,
        uint *lcg_state,
        int max_hits)
{
	/* Only intersect with matching object, for instanced objects we
	 * already know we are only intersecting the right object. */
	if(object == OBJECT_NONE) {
		if(kernel_tex_fetch(__prim_object, prim_addr) != local_object) {
			return false;
		}
	}

	const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, prim_addr);
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
	const ssef *ssef_verts = (ssef*)&kg->__prim_tri_verts.data[tri_vindex];
#else
	const float3 tri_a = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+0)),
	             tri_b = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+1)),
	             tri_c = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+2));
#endif
	float t, u, v;
	if(!ray_triangle_intersect(P,
	                           dir,
	                           tmax,
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
	                           ssef_verts,
#else
	                           tri_a, tri_b, tri_c,
#endif
	                           &u, &v, &t))
	{
		return false;
	}

	/* If no actual hit information is requested, just return here. */
	if(max_hits == 0) {
		return true;
	}

	int hit;
	if(lcg_state) {
		/* Record up to max_hits intersections. */
		for(int i = min(max_hits, local_isect->num_hits) - 1; i >= 0; --i) {
			if(local_isect->hits[i].t == t) {
				return false;
			}
		}

		local_isect->num_hits++;

		if(local_isect->num_hits <= max_hits) {
			hit = local_isect->num_hits - 1;
		}
		else {
			/* reservoir sampling: if we are at the maximum number of
			 * hits, randomly replace element or skip it */
			hit = lcg_step_uint(lcg_state) % local_isect->num_hits;

			if(hit >= max_hits)
				return false;
		}
	}
	else {
		/* Record closest intersection only. */
		if(local_isect->num_hits && t > local_isect->hits[0].t) {
			return false;
		}

		hit = 0;
		local_isect->num_hits = 1;
	}

	/* Record intersection. */
	Intersection *isect = &local_isect->hits[hit];
	isect->prim = prim_addr;
	isect->object = object;
	isect->type = PRIMITIVE_TRIANGLE;
	isect->u = u;
	isect->v = v;
	isect->t = t;

	/* Record geometric normal. */
#if defined(__KERNEL_SSE2__) && defined(__KERNEL_SSE__)
	const float3 tri_a = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+0)),
	             tri_b = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+1)),
	             tri_c = float4_to_float3(kernel_tex_fetch(__prim_tri_verts, tri_vindex+2));
#endif
	local_isect->Ng[hit] = normalize(cross(tri_b - tri_a, tri_c - tri_a));

	return false;
}
#endif  /* __BVH_LOCAL__ */

/* Refine triangle intersection to more precise hit point. For rays that travel
 * far the precision is often not so good, this reintersects the primitive from
 * a closer distance. */

/* Reintersections uses the paper:
 *
 * Tomas Moeller
 * Fast, minimum storage ray/triangle intersection
 * http://www.cs.virginia.edu/~gfx/Courses/2003/ImageSynthesis/papers/Acceleration/Fast%20MinimumStorage%20RayTriangle%20Intersection.pdf
 */

ccl_device_inline float3 triangle_refine(KernelGlobals *kg,
                                         ShaderData *sd,
                                         const Intersection *isect,
                                         const Ray *ray)
{
	float3 P = ray->P;
	float3 D = ray->D;
	float t = isect->t;

#ifdef __INTERSECTION_REFINE__
	if(isect->object != OBJECT_NONE) {
		if(UNLIKELY(t == 0.0f)) {
			return P;
		}
#  ifdef __OBJECT_MOTION__
		Transform tfm = sd->ob_itfm;
#  else
		Transform tfm = object_fetch_transform(kg, isect->object, OBJECT_INVERSE_TRANSFORM);
#  endif

		P = transform_point(&tfm, P);
		D = transform_direction(&tfm, D*t);
		D = normalize_len(D, &t);
	}

	P = P + D*t;

	const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, isect->prim);
	const float4 tri_a = kernel_tex_fetch(__prim_tri_verts, tri_vindex+0),
	             tri_b = kernel_tex_fetch(__prim_tri_verts, tri_vindex+1),
	             tri_c = kernel_tex_fetch(__prim_tri_verts, tri_vindex+2);
	float3 edge1 = make_float3(tri_a.x - tri_c.x, tri_a.y - tri_c.y, tri_a.z - tri_c.z);
	float3 edge2 = make_float3(tri_b.x - tri_c.x, tri_b.y - tri_c.y, tri_b.z - tri_c.z);
	float3 tvec = make_float3(P.x - tri_c.x, P.y - tri_c.y, P.z - tri_c.z);
	float3 qvec = cross(tvec, edge1);
	float3 pvec = cross(D, edge2);
	float det = dot(edge1, pvec);
	if(det != 0.0f) {
		/* If determinant is zero it means ray lies in the plane of
		 * the triangle. It is possible in theory due to watertight
		 * nature of triangle intersection. For such cases we simply
		 * don't refine intersection hoping it'll go all fine.
		 */
		float rt = dot(edge2, qvec) / det;
		P = P + D*rt;
	}

	if(isect->object != OBJECT_NONE) {
#  ifdef __OBJECT_MOTION__
		Transform tfm = sd->ob_tfm;
#  else
		Transform tfm = object_fetch_transform(kg, isect->object, OBJECT_TRANSFORM);
#  endif

		P = transform_point(&tfm, P);
	}

	return P;
#else
	return P + D*t;
#endif
}

/* Same as above, except that isect->t is assumed to be in object space for
 * instancing.
 */
ccl_device_inline float3 triangle_refine_local(KernelGlobals *kg,
                                               ShaderData *sd,
                                               const Intersection *isect,
                                               const Ray *ray)
{
	float3 P = ray->P;
	float3 D = ray->D;
	float t = isect->t;

	if(isect->object != OBJECT_NONE) {
#ifdef __OBJECT_MOTION__
		Transform tfm = sd->ob_itfm;
#else
		Transform tfm = object_fetch_transform(kg,
		                                       isect->object,
		                                       OBJECT_INVERSE_TRANSFORM);
#endif

		P = transform_point(&tfm, P);
		D = transform_direction(&tfm, D);
		D = normalize(D);
	}

	P = P + D*t;

#ifdef __INTERSECTION_REFINE__
	const uint tri_vindex = kernel_tex_fetch(__prim_tri_index, isect->prim);
	const float4 tri_a = kernel_tex_fetch(__prim_tri_verts, tri_vindex+0),
	             tri_b = kernel_tex_fetch(__prim_tri_verts, tri_vindex+1),
	             tri_c = kernel_tex_fetch(__prim_tri_verts, tri_vindex+2);
	float3 edge1 = make_float3(tri_a.x - tri_c.x, tri_a.y - tri_c.y, tri_a.z - tri_c.z);
	float3 edge2 = make_float3(tri_b.x - tri_c.x, tri_b.y - tri_c.y, tri_b.z - tri_c.z);
	float3 tvec = make_float3(P.x - tri_c.x, P.y - tri_c.y, P.z - tri_c.z);
	float3 qvec = cross(tvec, edge1);
	float3 pvec = cross(D, edge2);
	float det = dot(edge1, pvec);
	if(det != 0.0f) {
		/* If determinant is zero it means ray lies in the plane of
		 * the triangle. It is possible in theory due to watertight
		 * nature of triangle intersection. For such cases we simply
		 * don't refine intersection hoping it'll go all fine.
		 */
		float rt = dot(edge2, qvec) / det;
		P = P + D*rt;
	}
#endif  /* __INTERSECTION_REFINE__ */

	if(isect->object != OBJECT_NONE) {
#ifdef __OBJECT_MOTION__
		Transform tfm = sd->ob_tfm;
#else
		Transform tfm = object_fetch_transform(kg,
		                                       isect->object,
		                                       OBJECT_TRANSFORM);
#endif

		P = transform_point(&tfm, P);
	}

	return P;
}

CCL_NAMESPACE_END