diff options
author | Julian Eisel <julian@blender.org> | 2020-07-01 18:13:57 +0300 |
---|---|---|
committer | Julian Eisel <julian@blender.org> | 2020-07-01 18:13:57 +0300 |
commit | 0829cebeb024095c268f190c34daa8ae9a5a224c (patch) | |
tree | 12ee5a4a1c2a32e12eff47c8eb9bb0ed217791c1 /intern/cycles/kernel/geom/geom_triangle_intersect.h | |
parent | cfde6ebf450594faa57c4bfeaecff10fe512c91b (diff) | |
parent | 42be3964eb201180f6b0fa1ff6ce43b8c3845bc2 (diff) |
Merge branch 'master' into asset-uuid--archivedasset-uuid--archived
Diffstat (limited to 'intern/cycles/kernel/geom/geom_triangle_intersect.h')
-rw-r--r-- | intern/cycles/kernel/geom/geom_triangle_intersect.h | 427 |
1 files changed, 0 insertions, 427 deletions
diff --git a/intern/cycles/kernel/geom/geom_triangle_intersect.h b/intern/cycles/kernel/geom/geom_triangle_intersect.h index 6604806f73b..b0cce274b94 100644 --- a/intern/cycles/kernel/geom/geom_triangle_intersect.h +++ b/intern/cycles/kernel/geom/geom_triangle_intersect.h @@ -71,433 +71,6 @@ ccl_device_inline bool triangle_intersect(KernelGlobals *kg, 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) - int mask_final = _mm256_movemask_ps(_mm256_castsi256_ps(mask_final_256)); - if ((mask_final & prim_num_mask) == 0) { - return false; - } - while (mask_final != 0) { - const int i = __bscf(mask_final); - if (i >= prim_num) { - return false; - } -# ifdef __VISIBILITY_FLAG__ - if ((kernel_tex_fetch(__prim_visibility, (prim_addr + i)) & visibility) == 0) { - continue; - } -# endif - __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); - (*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; - } - return false; - } - 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. |