341 lines
13 KiB
C++
341 lines
13 KiB
C++
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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/* Triangle Primitive
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*
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* Basic triangle with 3 vertices is used to represent mesh surfaces. For BVH
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* ray intersection we use a precomputed triangle storage to accelerate
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* intersection at the cost of more memory usage */
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#pragma once
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#include "kernel/globals.h"
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#include "kernel/geom/attribute.h"
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#include "kernel/geom/object.h"
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CCL_NAMESPACE_BEGIN
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/* Evaluate a quantity at barycentric coordinates u, v, given the values at three triangle
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* vertices. */
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template<typename T>
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ccl_device_inline T
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triangle_interpolate(const float u, const float v, const T f0, const T f1, const T f2)
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{
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return (1.0f - u - v) * f0 + u * f1 + v * f2;
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}
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/* Normal on triangle. */
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ccl_device_inline float3 triangle_normal(KernelGlobals kg, ccl_private ShaderData *sd)
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{
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/* load triangle vertices */
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const int position_offset = kernel_data_fetch(objects, sd->object).position_offset;
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, sd->prim);
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const float3 v0 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.x);
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const float3 v1 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.y);
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const float3 v2 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.z);
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/* return normal */
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if (object_negative_scale_applied(sd->object_flag)) {
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return normalize(cross(v2 - v0, v1 - v0));
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}
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return normalize(cross(v1 - v0, v2 - v0));
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}
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/* Face normal of undisplaced triangle, from vertex positions stored as attribute. */
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ccl_device_inline float3 triangle_face_normal_undisplaced(KernelGlobals kg,
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ccl_private const ShaderData *sd,
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const int position_attr_offset)
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{
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, sd->prim);
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const float3 v0 = attribute_data_fetch<float3>(
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kg, ATTR_ELEMENT_VERTEX, position_attr_offset + tri_vindex.x);
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const float3 v1 = attribute_data_fetch<float3>(
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kg, ATTR_ELEMENT_VERTEX, position_attr_offset + tri_vindex.y);
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const float3 v2 = attribute_data_fetch<float3>(
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kg, ATTR_ELEMENT_VERTEX, position_attr_offset + tri_vindex.z);
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if (object_negative_scale_applied(sd->object_flag)) {
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return normalize(cross(v2 - v0, v1 - v0));
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}
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return normalize(cross(v1 - v0, v2 - v0));
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}
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/* Point and normal on triangle. */
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ccl_device_inline void triangle_point_normal(KernelGlobals kg,
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const int object,
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const int prim,
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const float u,
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const float v,
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ccl_private float3 *P,
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ccl_private float3 *Ng,
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ccl_private int *shader)
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{
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/* load triangle vertices */
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const int position_offset = kernel_data_fetch(objects, object).position_offset;
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, prim);
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const float3 v0 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.x);
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const float3 v1 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.y);
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const float3 v2 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.z);
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/* compute point */
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const float w = 1.0f - u - v;
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*P = (w * v0 + u * v1 + v * v2);
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/* get object flags */
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const uint object_flag = kernel_data_fetch(object_flag, object);
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/* compute normal */
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if (object_negative_scale_applied(object_flag)) {
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*Ng = normalize(cross(v2 - v0, v1 - v0));
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}
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else {
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*Ng = normalize(cross(v1 - v0, v2 - v0));
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}
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/* shader */
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*shader = kernel_data_fetch(tri_shader, prim);
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}
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/* Triangle vertex locations */
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ccl_device_inline void triangle_vertices(KernelGlobals kg,
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const int object,
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const int prim,
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float3 P[3])
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{
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const int position_offset = kernel_data_fetch(objects, object).position_offset;
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, prim);
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P[0] = kernel_data_fetch(tri_verts, position_offset + tri_vindex.x);
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P[1] = kernel_data_fetch(tri_verts, position_offset + tri_vindex.y);
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P[2] = kernel_data_fetch(tri_verts, position_offset + tri_vindex.z);
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}
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/* Triangle vertex locations and vertex normals */
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ccl_device_inline void triangle_vertices_and_normals(KernelGlobals kg,
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ccl_private const ShaderData *sd,
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float3 P[3],
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float3 N[3])
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{
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const int position_offset = kernel_data_fetch(objects, sd->object).position_offset;
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, sd->prim);
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P[0] = kernel_data_fetch(tri_verts, position_offset + tri_vindex.x);
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P[1] = kernel_data_fetch(tri_verts, position_offset + tri_vindex.y);
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P[2] = kernel_data_fetch(tri_verts, position_offset + tri_vindex.z);
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const int normal_offset = kernel_data_fetch(objects, sd->object).normal_offset;
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int i0, i1, i2;
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if (sd->object_flag & SD_OBJECT_HAS_CORNER_NORMALS) {
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i0 = sd->prim * 3 + 0;
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i1 = sd->prim * 3 + 1;
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i2 = sd->prim * 3 + 2;
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}
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else {
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i0 = tri_vindex.x;
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i1 = tri_vindex.y;
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i2 = tri_vindex.z;
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}
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attribute_data_fetch_normals(kg, normal_offset, i0, i1, i2, N);
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}
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/* Interpolate smooth vertex normal from vertices */
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ccl_device_inline float3 triangle_smooth_normal(
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KernelGlobals kg, float3 Ng, int object, int object_flag, int prim, float u, float v)
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{
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const int normal_offset = kernel_data_fetch(objects, object).normal_offset;
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int i0, i1, i2;
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if (object_flag & SD_OBJECT_HAS_CORNER_NORMALS) {
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i0 = prim * 3 + 0;
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i1 = prim * 3 + 1;
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i2 = prim * 3 + 2;
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}
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else {
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, prim);
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i0 = tri_vindex.x;
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i1 = tri_vindex.y;
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i2 = tri_vindex.z;
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}
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const float3 N = safe_normalize(
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attribute_data_interpolate_normals(kg, normal_offset, i0, i1, i2, u, v));
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return is_zero(N) ? Ng : N;
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}
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/* Compute triangle normals at the hit position, and offsetted positions in x and y direction for
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* bump mapping. */
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ccl_device_inline float3 triangle_smooth_normal(KernelGlobals kg,
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const float3 Ng,
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const int object,
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const int object_flag,
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const int prim,
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const float u,
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float v,
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const differential du,
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const differential dv,
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ccl_private float3 &N_x,
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ccl_private float3 &N_y)
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{
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const int normal_offset = kernel_data_fetch(objects, object).normal_offset;
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int i0, i1, i2;
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if (object_flag & SD_OBJECT_HAS_CORNER_NORMALS) {
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i0 = prim * 3 + 0;
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i1 = prim * 3 + 1;
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i2 = prim * 3 + 2;
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}
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else {
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, prim);
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i0 = tri_vindex.x;
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i1 = tri_vindex.y;
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i2 = tri_vindex.z;
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}
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float3 n[3];
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attribute_data_fetch_normals(kg, normal_offset, i0, i1, i2, n);
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const float3 N = safe_normalize(triangle_interpolate(u, v, n[0], n[1], n[2]));
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N_x = safe_normalize(triangle_interpolate(u + du.dx, v + dv.dx, n[0], n[1], n[2]));
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N_y = safe_normalize(triangle_interpolate(u + du.dy, v + dv.dy, n[0], n[1], n[2]));
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N_x = is_zero(N_x) ? Ng : N_x;
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N_y = is_zero(N_y) ? Ng : N_y;
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return is_zero(N) ? Ng : N;
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}
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/* Special variation for normal mapping, where we want to match the unnormalized object
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* space interpolation as assumed by normal map baking exactly. An exact match avoids
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* discontinuities across UV seams.*/
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ccl_device_inline float3 triangle_smooth_normal_unnormalized_object_space(
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KernelGlobals kg, ccl_private const ShaderData *sd)
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{
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const int normal_offset = kernel_data_fetch(objects, sd->object).normal_offset;
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int i0, i1, i2;
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if (sd->object_flag & SD_OBJECT_HAS_CORNER_NORMALS) {
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i0 = sd->prim * 3 + 0;
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i1 = sd->prim * 3 + 1;
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i2 = sd->prim * 3 + 2;
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}
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else {
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, sd->prim);
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i0 = tri_vindex.x;
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i1 = tri_vindex.y;
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i2 = tri_vindex.z;
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}
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float3 n[3];
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attribute_data_fetch_normals(kg, normal_offset, i0, i1, i2, n);
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if (sd->object_flag & SD_OBJECT_TRANSFORM_APPLIED) {
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object_inverse_normal_transform(kg, sd, &n[0]);
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object_inverse_normal_transform(kg, sd, &n[1]);
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object_inverse_normal_transform(kg, sd, &n[2]);
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}
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const float3 N = safe_normalize(triangle_interpolate(sd->u, sd->v, n[0], n[1], n[2]));
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return is_zero(N) ? sd->Ng : N;
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}
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/* Ray differentials on triangle */
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ccl_device_inline void triangle_dPdudv(KernelGlobals kg,
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const int object,
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const int prim,
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ccl_private float3 *dPdu,
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ccl_private float3 *dPdv)
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{
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/* fetch triangle vertex coordinates */
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const int position_offset = kernel_data_fetch(objects, object).position_offset;
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, prim);
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const float3 p0 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.x);
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const float3 p1 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.y);
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const float3 p2 = kernel_data_fetch(tri_verts, position_offset + tri_vindex.z);
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/* compute derivatives of P w.r.t. uv */
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*dPdu = (p1 - p0);
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*dPdv = (p2 - p0);
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}
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/* Partial derivative of f w.r.t. x, namely ∂f/∂x.
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* f is a function of barycentric coordinates u, v, given by
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* f(u, v) = f1 * u + f2 * v + f0 * (1 - u - v),
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* the derivatives are
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* ∂f/∂u = (f1 - f0), ∂f/∂v = (f2 - f0).
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* The partial derivative in x is
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* ∂f/∂x = ∂f/∂u * ∂u/∂x + ∂f/∂v * ∂v/∂x
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* = (f1 - f0) * du.dx + (f2 - f0) * dv.dx. */
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template<typename T>
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ccl_device_inline T triangle_attribute_dfdx(const ccl_private differential &du,
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const ccl_private differential &dv,
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const ccl_private T &f0,
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const ccl_private T &f1,
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const ccl_private T &f2)
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{
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return du.dx * f1 + dv.dx * f2 - (du.dx + dv.dx) * f0;
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}
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/* Partial derivative of f w.r.t. in x, namely ∂f/∂y, similarly computed as ∂f/∂x above. */
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template<typename T>
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ccl_device_inline T triangle_attribute_dfdy(const ccl_private differential &du,
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const ccl_private differential &dv,
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const ccl_private T &f0,
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const ccl_private T &f1,
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const ccl_private T &f2)
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{
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return du.dy * f1 + dv.dy * f2 - (du.dy + dv.dy) * f0;
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}
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/* Read attributes on various triangle elements. T is the return type, which can be a plain type
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* (float, float3, etc.) or a dual type (dual1, dual3, etc.) to include derivatives. */
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template<typename T>
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ccl_device T triangle_attribute(KernelGlobals kg,
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const ccl_private ShaderData *sd,
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const AttributeDescriptor desc)
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{
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using BaseT = dual_base_t<T>;
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if (desc.element & (ATTR_ELEMENT_VERTEX | ATTR_ELEMENT_CORNER)) {
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int i0, i1, i2;
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if (desc.element & ATTR_ELEMENT_VERTEX) {
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const uint3 tri_vindex = kernel_data_fetch(tri_vindex, sd->prim);
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i0 = tri_vindex.x;
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i1 = tri_vindex.y;
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i2 = tri_vindex.z;
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}
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else {
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/* Corner attributes. */
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const int tri = sd->prim * 3;
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i0 = tri + 0;
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i1 = tri + 1;
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i2 = tri + 2;
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}
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BaseT f[3];
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attribute_data_fetch_3<BaseT>(kg, desc.element, desc.offset, i0, i1, i2, f);
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if constexpr (is_dual_v<T>) {
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T result;
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result.val = triangle_interpolate(sd->u, sd->v, f[0], f[1], f[2]);
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#ifdef __RAY_DIFFERENTIALS__
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result.dx = triangle_attribute_dfdx(sd->du, sd->dv, f[0], f[1], f[2]);
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result.dy = triangle_attribute_dfdy(sd->du, sd->dv, f[0], f[1], f[2]);
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#endif
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return result;
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}
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else {
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return triangle_interpolate(sd->u, sd->v, f[0], f[1], f[2]);
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}
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}
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if (desc.element & ATTR_ELEMENT_FACE) {
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return T(attribute_data_fetch<BaseT>(kg, desc.element, desc.offset + sd->prim));
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}
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return make_zero<T>();
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}
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CCL_NAMESPACE_END
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