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/*
* 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.
*/
CCL_NAMESPACE_BEGIN
/* Curve Primitive
*
* Curve primitive for rendering hair and fur. These can be render as flat
* ribbons or curves with actual thickness. The curve can also be rendered as
* line segments rather than curves for better performance.
*/
#ifdef __HAIR__
/* Interpolation of curve geometry */
ccl_device_inline float3 curvetangent(float t, float3 p0, float3 p1, float3 p2, float3 p3)
{
float fc = 0.71f;
float data[4];
float t2 = t * t;
data[0] = -3.0f * fc * t2 + 4.0f * fc * t - fc;
data[1] = 3.0f * (2.0f - fc) * t2 + 2.0f * (fc - 3.0f) * t;
data[2] = 3.0f * (fc - 2.0f) * t2 + 2.0f * (3.0f - 2.0f * fc) * t + fc;
data[3] = 3.0f * fc * t2 - 2.0f * fc * t;
return data[0] * p0 + data[1] * p1 + data[2] * p2 + data[3] * p3;
}
ccl_device_inline float3 curvepoint(float t, float3 p0, float3 p1, float3 p2, float3 p3)
{
float data[4];
float fc = 0.71f;
float t2 = t * t;
float t3 = t2 * t;
data[0] = -fc * t3 + 2.0f * fc * t2 - fc * t;
data[1] = (2.0f - fc) * t3 + (fc - 3.0f) * t2 + 1.0f;
data[2] = (fc - 2.0f) * t3 + (3.0f - 2.0f * fc) * t2 + fc * t;
data[3] = fc * t3 - fc * t2;
return data[0] * p0 + data[1] * p1 + data[2] * p2 + data[3] * p3;
}
/* Reading attributes on various curve elements */
ccl_device float curve_attribute_float(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float *dx, float *dy)
{
if(desc.element == ATTR_ELEMENT_CURVE) {
#ifdef __RAY_DIFFERENTIALS__
if(dx) *dx = 0.0f;
if(dy) *dy = 0.0f;
#endif
return kernel_tex_fetch(__attributes_float, desc.offset + sd->prim);
}
else if(desc.element == ATTR_ELEMENT_CURVE_KEY || desc.element == ATTR_ELEMENT_CURVE_KEY_MOTION) {
float4 curvedata = kernel_tex_fetch(__curves, sd->prim);
int k0 = __float_as_int(curvedata.x) + PRIMITIVE_UNPACK_SEGMENT(sd->type);
int k1 = k0 + 1;
float f0 = kernel_tex_fetch(__attributes_float, desc.offset + k0);
float f1 = kernel_tex_fetch(__attributes_float, desc.offset + k1);
#ifdef __RAY_DIFFERENTIALS__
if(dx) *dx = sd->du.dx*(f1 - f0);
if(dy) *dy = 0.0f;
#endif
return (1.0f - sd->u)*f0 + sd->u*f1;
}
else {
#ifdef __RAY_DIFFERENTIALS__
if(dx) *dx = 0.0f;
if(dy) *dy = 0.0f;
#endif
return 0.0f;
}
}
ccl_device float3 curve_attribute_float3(KernelGlobals *kg, const ShaderData *sd, const AttributeDescriptor desc, float3 *dx, float3 *dy)
{
if(desc.element == ATTR_ELEMENT_CURVE) {
/* idea: we can't derive any useful differentials here, but for tiled
* mipmap image caching it would be useful to avoid reading the highest
* detail level always. maybe a derivative based on the hair density
* could be computed somehow? */
#ifdef __RAY_DIFFERENTIALS__
if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
#endif
return float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + sd->prim));
}
else if(desc.element == ATTR_ELEMENT_CURVE_KEY || desc.element == ATTR_ELEMENT_CURVE_KEY_MOTION) {
float4 curvedata = kernel_tex_fetch(__curves, sd->prim);
int k0 = __float_as_int(curvedata.x) + PRIMITIVE_UNPACK_SEGMENT(sd->type);
int k1 = k0 + 1;
float3 f0 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + k0));
float3 f1 = float4_to_float3(kernel_tex_fetch(__attributes_float3, desc.offset + k1));
#ifdef __RAY_DIFFERENTIALS__
if(dx) *dx = sd->du.dx*(f1 - f0);
if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
#endif
return (1.0f - sd->u)*f0 + sd->u*f1;
}
else {
#ifdef __RAY_DIFFERENTIALS__
if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
#endif
return make_float3(0.0f, 0.0f, 0.0f);
}
}
/* Curve thickness */
ccl_device float curve_thickness(KernelGlobals *kg, ShaderData *sd)
{
float r = 0.0f;
if(sd->type & PRIMITIVE_ALL_CURVE) {
float4 curvedata = kernel_tex_fetch(__curves, sd->prim);
int k0 = __float_as_int(curvedata.x) + PRIMITIVE_UNPACK_SEGMENT(sd->type);
int k1 = k0 + 1;
float4 P_curve[2];
if(sd->type & PRIMITIVE_CURVE) {
P_curve[0]= kernel_tex_fetch(__curve_keys, k0);
P_curve[1]= kernel_tex_fetch(__curve_keys, k1);
}
else {
motion_curve_keys(kg, sd->object, sd->prim, sd->time, k0, k1, P_curve);
}
r = (P_curve[1].w - P_curve[0].w) * sd->u + P_curve[0].w;
}
return r*2.0f;
}
/* Curve location for motion pass, linear interpolation between keys and
* ignoring radius because we do the same for the motion keys */
ccl_device float3 curve_motion_center_location(KernelGlobals *kg, ShaderData *sd)
{
float4 curvedata = kernel_tex_fetch(__curves, sd->prim);
int k0 = __float_as_int(curvedata.x) + PRIMITIVE_UNPACK_SEGMENT(sd->type);
int k1 = k0 + 1;
float4 P_curve[2];
P_curve[0]= kernel_tex_fetch(__curve_keys, k0);
P_curve[1]= kernel_tex_fetch(__curve_keys, k1);
return float4_to_float3(P_curve[1]) * sd->u + float4_to_float3(P_curve[0]) * (1.0f - sd->u);
}
/* Curve tangent normal */
ccl_device float3 curve_tangent_normal(KernelGlobals *kg, ShaderData *sd)
{
float3 tgN = make_float3(0.0f,0.0f,0.0f);
if(sd->type & PRIMITIVE_ALL_CURVE) {
tgN = -(-sd->I - sd->dPdu * (dot(sd->dPdu,-sd->I) / len_squared(sd->dPdu)));
tgN = normalize(tgN);
/* need to find suitable scaled gd for corrected normal */
#if 0
tgN = normalize(tgN - gd * sd->dPdu);
#endif
}
return tgN;
}
/* Curve bounds utility function */
ccl_device_inline void curvebounds(float *lower, float *upper, float *extremta, float *extrema, float *extremtb, float *extremb, float p0, float p1, float p2, float p3)
{
float halfdiscroot = (p2 * p2 - 3 * p3 * p1);
float ta = -1.0f;
float tb = -1.0f;
*extremta = -1.0f;
*extremtb = -1.0f;
*upper = p0;
*lower = (p0 + p1) + (p2 + p3);
*extrema = *upper;
*extremb = *lower;
if(*lower >= *upper) {
*upper = *lower;
*lower = p0;
}
if(halfdiscroot >= 0) {
float inv3p3 = (1.0f/3.0f)/p3;
halfdiscroot = sqrtf(halfdiscroot);
ta = (-p2 - halfdiscroot) * inv3p3;
tb = (-p2 + halfdiscroot) * inv3p3;
}
float t2;
float t3;
if(ta > 0.0f && ta < 1.0f) {
t2 = ta * ta;
t3 = t2 * ta;
*extremta = ta;
*extrema = p3 * t3 + p2 * t2 + p1 * ta + p0;
*upper = fmaxf(*extrema, *upper);
*lower = fminf(*extrema, *lower);
}
if(tb > 0.0f && tb < 1.0f) {
t2 = tb * tb;
t3 = t2 * tb;
*extremtb = tb;
*extremb = p3 * t3 + p2 * t2 + p1 * tb + p0;
*upper = fmaxf(*extremb, *upper);
*lower = fminf(*extremb, *lower);
}
}
#endif /* __HAIR__ */
CCL_NAMESPACE_END
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