543bf28fb1
wi is the viewing direction, and wo is the illumination direction. Under this notation, BSDF sampling always samples from wi and outputs wo, which is consistent with most of the papers and mitsuba. This order is reversed compared with PBRT, although PBRT also traces from the camera.
330 lines
9.8 KiB
C
330 lines
9.8 KiB
C
/* SPDX-License-Identifier: Apache-2.0
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* Copyright 2011-2022 Blender Foundation */
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#pragma once
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CCL_NAMESPACE_BEGIN
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/* Curve Primitive
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*
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* Curve primitive for rendering hair and fur. These can be render as flat
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* ribbons or curves with actual thickness. The curve can also be rendered as
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* line segments rather than curves for better performance.
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*/
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#ifdef __HAIR__
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/* Reading attributes on various curve elements */
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ccl_device float curve_attribute_float(KernelGlobals kg,
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ccl_private const ShaderData *sd,
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const AttributeDescriptor desc,
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ccl_private float *dx,
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ccl_private float *dy)
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{
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if (desc.element & (ATTR_ELEMENT_CURVE_KEY | ATTR_ELEMENT_CURVE_KEY_MOTION)) {
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KernelCurve curve = kernel_data_fetch(curves, sd->prim);
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int k0 = curve.first_key + PRIMITIVE_UNPACK_SEGMENT(sd->type);
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int k1 = k0 + 1;
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float f0 = kernel_data_fetch(attributes_float, desc.offset + k0);
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float f1 = kernel_data_fetch(attributes_float, desc.offset + k1);
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = sd->du.dx * (f1 - f0);
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if (dy)
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*dy = 0.0f;
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# endif
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return (1.0f - sd->u) * f0 + sd->u * f1;
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}
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else {
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = 0.0f;
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if (dy)
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*dy = 0.0f;
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# endif
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if (desc.element & (ATTR_ELEMENT_CURVE | ATTR_ELEMENT_OBJECT | ATTR_ELEMENT_MESH)) {
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const int offset = (desc.element == ATTR_ELEMENT_CURVE) ? desc.offset + sd->prim :
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desc.offset;
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return kernel_data_fetch(attributes_float, offset);
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}
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else {
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return 0.0f;
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}
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}
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}
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ccl_device float2 curve_attribute_float2(KernelGlobals kg,
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ccl_private const ShaderData *sd,
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const AttributeDescriptor desc,
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ccl_private float2 *dx,
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ccl_private float2 *dy)
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{
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if (desc.element & (ATTR_ELEMENT_CURVE_KEY | ATTR_ELEMENT_CURVE_KEY_MOTION)) {
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KernelCurve curve = kernel_data_fetch(curves, sd->prim);
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int k0 = curve.first_key + PRIMITIVE_UNPACK_SEGMENT(sd->type);
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int k1 = k0 + 1;
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float2 f0 = kernel_data_fetch(attributes_float2, desc.offset + k0);
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float2 f1 = kernel_data_fetch(attributes_float2, desc.offset + k1);
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = sd->du.dx * (f1 - f0);
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if (dy)
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*dy = make_float2(0.0f, 0.0f);
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# endif
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return (1.0f - sd->u) * f0 + sd->u * f1;
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}
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else {
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/* idea: we can't derive any useful differentials here, but for tiled
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* mipmap image caching it would be useful to avoid reading the highest
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* detail level always. maybe a derivative based on the hair density
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* could be computed somehow? */
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = make_float2(0.0f, 0.0f);
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if (dy)
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*dy = make_float2(0.0f, 0.0f);
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# endif
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if (desc.element & (ATTR_ELEMENT_CURVE | ATTR_ELEMENT_OBJECT | ATTR_ELEMENT_MESH)) {
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const int offset = (desc.element == ATTR_ELEMENT_CURVE) ? desc.offset + sd->prim :
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desc.offset;
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return kernel_data_fetch(attributes_float2, offset);
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}
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else {
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return make_float2(0.0f, 0.0f);
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}
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}
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}
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ccl_device float3 curve_attribute_float3(KernelGlobals kg,
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ccl_private const ShaderData *sd,
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const AttributeDescriptor desc,
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ccl_private float3 *dx,
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ccl_private float3 *dy)
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{
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if (desc.element & (ATTR_ELEMENT_CURVE_KEY | ATTR_ELEMENT_CURVE_KEY_MOTION)) {
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KernelCurve curve = kernel_data_fetch(curves, sd->prim);
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int k0 = curve.first_key + PRIMITIVE_UNPACK_SEGMENT(sd->type);
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int k1 = k0 + 1;
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float3 f0 = kernel_data_fetch(attributes_float3, desc.offset + k0);
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float3 f1 = kernel_data_fetch(attributes_float3, desc.offset + k1);
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = sd->du.dx * (f1 - f0);
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if (dy)
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*dy = make_float3(0.0f, 0.0f, 0.0f);
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# endif
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return (1.0f - sd->u) * f0 + sd->u * f1;
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}
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else {
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = make_float3(0.0f, 0.0f, 0.0f);
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if (dy)
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*dy = make_float3(0.0f, 0.0f, 0.0f);
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# endif
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if (desc.element & (ATTR_ELEMENT_CURVE | ATTR_ELEMENT_OBJECT | ATTR_ELEMENT_MESH)) {
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const int offset = (desc.element == ATTR_ELEMENT_CURVE) ? desc.offset + sd->prim :
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desc.offset;
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return kernel_data_fetch(attributes_float3, offset);
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}
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else {
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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}
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}
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ccl_device float4 curve_attribute_float4(KernelGlobals kg,
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ccl_private const ShaderData *sd,
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const AttributeDescriptor desc,
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ccl_private float4 *dx,
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ccl_private float4 *dy)
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{
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if (desc.element & (ATTR_ELEMENT_CURVE_KEY | ATTR_ELEMENT_CURVE_KEY_MOTION)) {
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KernelCurve curve = kernel_data_fetch(curves, sd->prim);
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int k0 = curve.first_key + PRIMITIVE_UNPACK_SEGMENT(sd->type);
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int k1 = k0 + 1;
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float4 f0 = kernel_data_fetch(attributes_float4, desc.offset + k0);
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float4 f1 = kernel_data_fetch(attributes_float4, desc.offset + k1);
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = sd->du.dx * (f1 - f0);
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if (dy)
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*dy = zero_float4();
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# endif
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return (1.0f - sd->u) * f0 + sd->u * f1;
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}
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else {
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# ifdef __RAY_DIFFERENTIALS__
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if (dx)
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*dx = zero_float4();
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if (dy)
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*dy = zero_float4();
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# endif
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if (desc.element & (ATTR_ELEMENT_CURVE | ATTR_ELEMENT_OBJECT | ATTR_ELEMENT_MESH)) {
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const int offset = (desc.element == ATTR_ELEMENT_CURVE) ? desc.offset + sd->prim :
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desc.offset;
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return kernel_data_fetch(attributes_float4, offset);
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}
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else {
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return zero_float4();
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}
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}
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}
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/* Curve thickness */
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ccl_device float curve_thickness(KernelGlobals kg, ccl_private const ShaderData *sd)
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{
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float r = 0.0f;
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if (sd->type & PRIMITIVE_CURVE) {
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KernelCurve curve = kernel_data_fetch(curves, sd->prim);
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int k0 = curve.first_key + PRIMITIVE_UNPACK_SEGMENT(sd->type);
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int k1 = k0 + 1;
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float4 P_curve[2];
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if (!(sd->type & PRIMITIVE_MOTION)) {
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P_curve[0] = kernel_data_fetch(curve_keys, k0);
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P_curve[1] = kernel_data_fetch(curve_keys, k1);
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}
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else {
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motion_curve_keys_linear(kg, sd->object, sd->prim, sd->time, k0, k1, P_curve);
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}
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r = (P_curve[1].w - P_curve[0].w) * sd->u + P_curve[0].w;
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}
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return r * 2.0f;
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}
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/* Curve random */
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ccl_device float curve_random(KernelGlobals kg, ccl_private const ShaderData *sd)
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{
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if (sd->type & PRIMITIVE_CURVE) {
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const AttributeDescriptor desc = find_attribute(kg, sd, ATTR_STD_CURVE_RANDOM);
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return (desc.offset != ATTR_STD_NOT_FOUND) ? curve_attribute_float(kg, sd, desc, NULL, NULL) :
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0.0f;
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}
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return 0.0f;
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}
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/* Curve location for motion pass, linear interpolation between keys and
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* ignoring radius because we do the same for the motion keys */
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ccl_device float3 curve_motion_center_location(KernelGlobals kg, ccl_private const ShaderData *sd)
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{
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KernelCurve curve = kernel_data_fetch(curves, sd->prim);
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int k0 = curve.first_key + PRIMITIVE_UNPACK_SEGMENT(sd->type);
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int k1 = k0 + 1;
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float4 P_curve[2];
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P_curve[0] = kernel_data_fetch(curve_keys, k0);
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P_curve[1] = kernel_data_fetch(curve_keys, k1);
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return float4_to_float3(P_curve[1]) * sd->u + float4_to_float3(P_curve[0]) * (1.0f - sd->u);
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}
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/* Curve tangent normal */
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ccl_device float3 curve_tangent_normal(KernelGlobals kg, ccl_private const ShaderData *sd)
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{
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float3 tgN = make_float3(0.0f, 0.0f, 0.0f);
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if (sd->type & PRIMITIVE_CURVE) {
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tgN = -(-sd->wi - sd->dPdu * (dot(sd->dPdu, -sd->wi) / len_squared(sd->dPdu)));
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tgN = normalize(tgN);
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/* need to find suitable scaled gd for corrected normal */
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# if 0
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tgN = normalize(tgN - gd * sd->dPdu);
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# endif
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}
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return tgN;
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}
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/* Curve bounds utility function */
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ccl_device_inline void curvebounds(ccl_private float *lower,
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ccl_private float *upper,
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ccl_private float *extremta,
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ccl_private float *extrema,
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ccl_private float *extremtb,
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ccl_private float *extremb,
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float p0,
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float p1,
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float p2,
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float p3)
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{
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float halfdiscroot = (p2 * p2 - 3 * p3 * p1);
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float ta = -1.0f;
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float tb = -1.0f;
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*extremta = -1.0f;
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*extremtb = -1.0f;
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*upper = p0;
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*lower = (p0 + p1) + (p2 + p3);
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*extrema = *upper;
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*extremb = *lower;
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if (*lower >= *upper) {
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*upper = *lower;
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*lower = p0;
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}
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if (halfdiscroot >= 0) {
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float inv3p3 = (1.0f / 3.0f) / p3;
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halfdiscroot = sqrtf(halfdiscroot);
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ta = (-p2 - halfdiscroot) * inv3p3;
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tb = (-p2 + halfdiscroot) * inv3p3;
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}
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float t2;
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float t3;
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if (ta > 0.0f && ta < 1.0f) {
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t2 = ta * ta;
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t3 = t2 * ta;
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*extremta = ta;
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*extrema = p3 * t3 + p2 * t2 + p1 * ta + p0;
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*upper = fmaxf(*extrema, *upper);
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*lower = fminf(*extrema, *lower);
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}
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if (tb > 0.0f && tb < 1.0f) {
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t2 = tb * tb;
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t3 = t2 * tb;
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*extremtb = tb;
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*extremb = p3 * t3 + p2 * t2 + p1 * tb + p0;
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*upper = fmaxf(*extremb, *upper);
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*lower = fminf(*extremb, *lower);
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}
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}
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#endif /* __HAIR__ */
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CCL_NAMESPACE_END
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