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/* SPDX-License-Identifier: Apache-2.0
* Copyright 2013 Pixar. */
/** \file
* Based on code from OpenSubdiv.
*/
#pragma once
#include "util/color.h"
CCL_NAMESPACE_BEGIN
typedef struct PatchHandle {
int array_index, patch_index, vert_index;
} PatchHandle;
ccl_device_inline int patch_map_resolve_quadrant(float median,
ccl_private float *u,
ccl_private float *v)
{
int quadrant = -1;
if (*u < median) {
if (*v < median) {
quadrant = 0;
}
else {
quadrant = 1;
*v -= median;
}
}
else {
if (*v < median) {
quadrant = 3;
}
else {
quadrant = 2;
*v -= median;
}
*u -= median;
}
return quadrant;
}
/* retrieve PatchHandle from patch coords */
ccl_device_inline PatchHandle
patch_map_find_patch(KernelGlobals kg, int object, int patch, float u, float v)
{
PatchHandle handle;
kernel_assert((u >= 0.0f) && (u <= 1.0f) && (v >= 0.0f) && (v <= 1.0f));
int node = (object_patch_map_offset(kg, object) + patch) / 2;
float median = 0.5f;
for (int depth = 0; depth < 0xff; depth++) {
float delta = median * 0.5f;
int quadrant = patch_map_resolve_quadrant(median, &u, &v);
kernel_assert(quadrant >= 0);
uint child = kernel_tex_fetch(__patches, node + quadrant);
/* is the quadrant a hole? */
if (!(child & PATCH_MAP_NODE_IS_SET)) {
handle.array_index = -1;
return handle;
}
uint index = child & PATCH_MAP_NODE_INDEX_MASK;
if (child & PATCH_MAP_NODE_IS_LEAF) {
handle.array_index = kernel_tex_fetch(__patches, index + 0);
handle.patch_index = kernel_tex_fetch(__patches, index + 1);
handle.vert_index = kernel_tex_fetch(__patches, index + 2);
return handle;
}
else {
node = index;
}
median = delta;
}
/* no leaf found */
kernel_assert(0);
handle.array_index = -1;
return handle;
}
ccl_device_inline void patch_eval_bspline_weights(float t,
ccl_private float *point,
ccl_private float *deriv)
{
/* The four uniform cubic B-Spline basis functions evaluated at t */
float inv_6 = 1.0f / 6.0f;
float t2 = t * t;
float t3 = t * t2;
point[0] = inv_6 * (1.0f - 3.0f * (t - t2) - t3);
point[1] = inv_6 * (4.0f - 6.0f * t2 + 3.0f * t3);
point[2] = inv_6 * (1.0f + 3.0f * (t + t2 - t3));
point[3] = inv_6 * t3;
/* Derivatives of the above four basis functions at t */
deriv[0] = -0.5f * t2 + t - 0.5f;
deriv[1] = 1.5f * t2 - 2.0f * t;
deriv[2] = -1.5f * t2 + t + 0.5f;
deriv[3] = 0.5f * t2;
}
ccl_device_inline void patch_eval_adjust_boundary_weights(uint bits,
ccl_private float *s,
ccl_private float *t)
{
int boundary = ((bits >> 8) & 0xf);
if (boundary & 1) {
t[2] -= t[0];
t[1] += 2 * t[0];
t[0] = 0;
}
if (boundary & 2) {
s[1] -= s[3];
s[2] += 2 * s[3];
s[3] = 0;
}
if (boundary & 4) {
t[1] -= t[3];
t[2] += 2 * t[3];
t[3] = 0;
}
if (boundary & 8) {
s[2] -= s[0];
s[1] += 2 * s[0];
s[0] = 0;
}
}
ccl_device_inline int patch_eval_depth(uint patch_bits)
{
return (patch_bits & 0xf);
}
ccl_device_inline float patch_eval_param_fraction(uint patch_bits)
{
bool non_quad_root = (patch_bits >> 4) & 0x1;
int depth = patch_eval_depth(patch_bits);
if (non_quad_root) {
return 1.0f / (float)(1 << (depth - 1));
}
else {
return 1.0f / (float)(1 << depth);
}
}
ccl_device_inline void patch_eval_normalize_coords(uint patch_bits,
ccl_private float *u,
ccl_private float *v)
{
float frac = patch_eval_param_fraction(patch_bits);
int iu = (patch_bits >> 22) & 0x3ff;
int iv = (patch_bits >> 12) & 0x3ff;
/* top left corner */
float pu = (float)iu * frac;
float pv = (float)iv * frac;
/* normalize uv coordinates */
*u = (*u - pu) / frac;
*v = (*v - pv) / frac;
}
/* retrieve patch control indices */
ccl_device_inline int patch_eval_indices(KernelGlobals kg,
ccl_private const PatchHandle *handle,
int channel,
int indices[PATCH_MAX_CONTROL_VERTS])
{
int index_base = kernel_tex_fetch(__patches, handle->array_index + 2) + handle->vert_index;
/* XXX: regular patches only */
for (int i = 0; i < 16; i++) {
indices[i] = kernel_tex_fetch(__patches, index_base + i);
}
return 16;
}
/* evaluate patch basis functions */
ccl_device_inline void patch_eval_basis(KernelGlobals kg,
ccl_private const PatchHandle *handle,
float u,
float v,
float weights[PATCH_MAX_CONTROL_VERTS],
float weights_du[PATCH_MAX_CONTROL_VERTS],
float weights_dv[PATCH_MAX_CONTROL_VERTS])
{
uint patch_bits = kernel_tex_fetch(__patches, handle->patch_index + 1); /* read patch param */
float d_scale = 1 << patch_eval_depth(patch_bits);
bool non_quad_root = (patch_bits >> 4) & 0x1;
if (non_quad_root) {
d_scale *= 0.5f;
}
patch_eval_normalize_coords(patch_bits, &u, &v);
/* XXX: regular patches only for now. */
float s[4], t[4], ds[4], dt[4];
patch_eval_bspline_weights(u, s, ds);
patch_eval_bspline_weights(v, t, dt);
patch_eval_adjust_boundary_weights(patch_bits, s, t);
patch_eval_adjust_boundary_weights(patch_bits, ds, dt);
for (int k = 0; k < 4; k++) {
for (int l = 0; l < 4; l++) {
weights[4 * k + l] = s[l] * t[k];
weights_du[4 * k + l] = ds[l] * t[k] * d_scale;
weights_dv[4 * k + l] = s[l] * dt[k] * d_scale;
}
}
}
/* generic function for evaluating indices and weights from patch coords */
ccl_device_inline int patch_eval_control_verts(KernelGlobals kg,
int object,
int patch,
float u,
float v,
int channel,
int indices[PATCH_MAX_CONTROL_VERTS],
float weights[PATCH_MAX_CONTROL_VERTS],
float weights_du[PATCH_MAX_CONTROL_VERTS],
float weights_dv[PATCH_MAX_CONTROL_VERTS])
{
PatchHandle handle = patch_map_find_patch(kg, object, patch, u, v);
kernel_assert(handle.array_index >= 0);
int num_control = patch_eval_indices(kg, &handle, channel, indices);
patch_eval_basis(kg, &handle, u, v, weights, weights_du, weights_dv);
return num_control;
}
/* functions for evaluating attributes on patches */
ccl_device float patch_eval_float(KernelGlobals kg,
ccl_private const ShaderData *sd,
int offset,
int patch,
float u,
float v,
int channel,
ccl_private float *du,
ccl_private float *dv)
{
int indices[PATCH_MAX_CONTROL_VERTS];
float weights[PATCH_MAX_CONTROL_VERTS];
float weights_du[PATCH_MAX_CONTROL_VERTS];
float weights_dv[PATCH_MAX_CONTROL_VERTS];
int num_control = patch_eval_control_verts(
kg, sd->object, patch, u, v, channel, indices, weights, weights_du, weights_dv);
float val = 0.0f;
if (du)
*du = 0.0f;
if (dv)
*dv = 0.0f;
for (int i = 0; i < num_control; i++) {
float v = kernel_tex_fetch(__attributes_float, offset + indices[i]);
val += v * weights[i];
if (du)
*du += v * weights_du[i];
if (dv)
*dv += v * weights_dv[i];
}
return val;
}
ccl_device float2 patch_eval_float2(KernelGlobals kg,
ccl_private const ShaderData *sd,
int offset,
int patch,
float u,
float v,
int channel,
ccl_private float2 *du,
ccl_private float2 *dv)
{
int indices[PATCH_MAX_CONTROL_VERTS];
float weights[PATCH_MAX_CONTROL_VERTS];
float weights_du[PATCH_MAX_CONTROL_VERTS];
float weights_dv[PATCH_MAX_CONTROL_VERTS];
int num_control = patch_eval_control_verts(
kg, sd->object, patch, u, v, channel, indices, weights, weights_du, weights_dv);
float2 val = make_float2(0.0f, 0.0f);
if (du)
*du = make_float2(0.0f, 0.0f);
if (dv)
*dv = make_float2(0.0f, 0.0f);
for (int i = 0; i < num_control; i++) {
float2 v = kernel_tex_fetch(__attributes_float2, offset + indices[i]);
val += v * weights[i];
if (du)
*du += v * weights_du[i];
if (dv)
*dv += v * weights_dv[i];
}
return val;
}
ccl_device float3 patch_eval_float3(KernelGlobals kg,
ccl_private const ShaderData *sd,
int offset,
int patch,
float u,
float v,
int channel,
ccl_private float3 *du,
ccl_private float3 *dv)
{
int indices[PATCH_MAX_CONTROL_VERTS];
float weights[PATCH_MAX_CONTROL_VERTS];
float weights_du[PATCH_MAX_CONTROL_VERTS];
float weights_dv[PATCH_MAX_CONTROL_VERTS];
int num_control = patch_eval_control_verts(
kg, sd->object, patch, u, v, channel, indices, weights, weights_du, weights_dv);
float3 val = make_float3(0.0f, 0.0f, 0.0f);
if (du)
*du = make_float3(0.0f, 0.0f, 0.0f);
if (dv)
*dv = make_float3(0.0f, 0.0f, 0.0f);
for (int i = 0; i < num_control; i++) {
float3 v = kernel_tex_fetch(__attributes_float3, offset + indices[i]);
val += v * weights[i];
if (du)
*du += v * weights_du[i];
if (dv)
*dv += v * weights_dv[i];
}
return val;
}
ccl_device float4 patch_eval_float4(KernelGlobals kg,
ccl_private const ShaderData *sd,
int offset,
int patch,
float u,
float v,
int channel,
ccl_private float4 *du,
ccl_private float4 *dv)
{
int indices[PATCH_MAX_CONTROL_VERTS];
float weights[PATCH_MAX_CONTROL_VERTS];
float weights_du[PATCH_MAX_CONTROL_VERTS];
float weights_dv[PATCH_MAX_CONTROL_VERTS];
int num_control = patch_eval_control_verts(
kg, sd->object, patch, u, v, channel, indices, weights, weights_du, weights_dv);
float4 val = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
if (du)
*du = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
if (dv)
*dv = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
for (int i = 0; i < num_control; i++) {
float4 v = kernel_tex_fetch(__attributes_float4, offset + indices[i]);
val += v * weights[i];
if (du)
*du += v * weights_du[i];
if (dv)
*dv += v * weights_dv[i];
}
return val;
}
ccl_device float4 patch_eval_uchar4(KernelGlobals kg,
ccl_private const ShaderData *sd,
int offset,
int patch,
float u,
float v,
int channel,
ccl_private float4 *du,
ccl_private float4 *dv)
{
int indices[PATCH_MAX_CONTROL_VERTS];
float weights[PATCH_MAX_CONTROL_VERTS];
float weights_du[PATCH_MAX_CONTROL_VERTS];
float weights_dv[PATCH_MAX_CONTROL_VERTS];
int num_control = patch_eval_control_verts(
kg, sd->object, patch, u, v, channel, indices, weights, weights_du, weights_dv);
float4 val = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
if (du)
*du = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
if (dv)
*dv = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
for (int i = 0; i < num_control; i++) {
float4 v = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, offset + indices[i])));
val += v * weights[i];
if (du)
*du += v * weights_du[i];
if (dv)
*dv += v * weights_dv[i];
}
return val;
}
CCL_NAMESPACE_END
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