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Diffstat (limited to 'intern/cycles/kernel/sample/mapping.h')
| -rw-r--r-- | intern/cycles/kernel/sample/mapping.h | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/intern/cycles/kernel/sample/mapping.h b/intern/cycles/kernel/sample/mapping.h new file mode 100644 index 00000000000..3297aa2a29a --- /dev/null +++ b/intern/cycles/kernel/sample/mapping.h @@ -0,0 +1,177 @@ +/* + * Parts adapted from Open Shading Language with this license: + * + * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al. + * All Rights Reserved. + * + * Modifications Copyright 2011, Blender Foundation. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * * Neither the name of Sony Pictures Imageworks nor the names of its + * contributors may be used to endorse or promote products derived from + * this software without specific prior written permission. + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#pragma once + +CCL_NAMESPACE_BEGIN + +/* distribute uniform xy on [0,1] over unit disk [-1,1] */ +ccl_device void to_unit_disk(ccl_private float *x, ccl_private float *y) +{ + float phi = M_2PI_F * (*x); + float r = sqrtf(*y); + + *x = r * cosf(phi); + *y = r * sinf(phi); +} + +/* return an orthogonal tangent and bitangent given a normal and tangent that + * may not be exactly orthogonal */ +ccl_device void make_orthonormals_tangent(const float3 N, + const float3 T, + ccl_private float3 *a, + ccl_private float3 *b) +{ + *b = normalize(cross(N, T)); + *a = cross(*b, N); +} + +/* sample direction with cosine weighted distributed in hemisphere */ +ccl_device_inline void sample_cos_hemisphere( + const float3 N, float randu, float randv, ccl_private float3 *omega_in, ccl_private float *pdf) +{ + to_unit_disk(&randu, &randv); + float costheta = sqrtf(max(1.0f - randu * randu - randv * randv, 0.0f)); + float3 T, B; + make_orthonormals(N, &T, &B); + *omega_in = randu * T + randv * B + costheta * N; + *pdf = costheta * M_1_PI_F; +} + +/* sample direction uniformly distributed in hemisphere */ +ccl_device_inline void sample_uniform_hemisphere( + const float3 N, float randu, float randv, ccl_private float3 *omega_in, ccl_private float *pdf) +{ + float z = randu; + float r = sqrtf(max(0.0f, 1.0f - z * z)); + float phi = M_2PI_F * randv; + float x = r * cosf(phi); + float y = r * sinf(phi); + + float3 T, B; + make_orthonormals(N, &T, &B); + *omega_in = x * T + y * B + z * N; + *pdf = 0.5f * M_1_PI_F; +} + +/* sample direction uniformly distributed in cone */ +ccl_device_inline void sample_uniform_cone(const float3 N, + float angle, + float randu, + float randv, + ccl_private float3 *omega_in, + ccl_private float *pdf) +{ + float zMin = cosf(angle); + float z = zMin - zMin * randu + randu; + float r = safe_sqrtf(1.0f - sqr(z)); + float phi = M_2PI_F * randv; + float x = r * cosf(phi); + float y = r * sinf(phi); + + float3 T, B; + make_orthonormals(N, &T, &B); + *omega_in = x * T + y * B + z * N; + *pdf = M_1_2PI_F / (1.0f - zMin); +} + +ccl_device_inline float pdf_uniform_cone(const float3 N, float3 D, float angle) +{ + float zMin = cosf(angle); + float z = dot(N, D); + if (z > zMin) { + return M_1_2PI_F / (1.0f - zMin); + } + return 0.0f; +} + +/* sample uniform point on the surface of a sphere */ +ccl_device float3 sample_uniform_sphere(float u1, float u2) +{ + float z = 1.0f - 2.0f * u1; + float r = sqrtf(fmaxf(0.0f, 1.0f - z * z)); + float phi = M_2PI_F * u2; + float x = r * cosf(phi); + float y = r * sinf(phi); + + return make_float3(x, y, z); +} + +/* distribute uniform xy on [0,1] over unit disk [-1,1], with concentric mapping + * to better preserve stratification for some RNG sequences */ +ccl_device float2 concentric_sample_disk(float u1, float u2) +{ + float phi, r; + float a = 2.0f * u1 - 1.0f; + float b = 2.0f * u2 - 1.0f; + + if (a == 0.0f && b == 0.0f) { + return zero_float2(); + } + else if (a * a > b * b) { + r = a; + phi = M_PI_4_F * (b / a); + } + else { + r = b; + phi = M_PI_2_F - M_PI_4_F * (a / b); + } + + return make_float2(r * cosf(phi), r * sinf(phi)); +} + +/* sample point in unit polygon with given number of corners and rotation */ +ccl_device float2 regular_polygon_sample(float corners, float rotation, float u, float v) +{ + /* sample corner number and reuse u */ + float corner = floorf(u * corners); + u = u * corners - corner; + + /* uniform sampled triangle weights */ + u = sqrtf(u); + v = v * u; + u = 1.0f - u; + + /* point in triangle */ + float angle = M_PI_F / corners; + float2 p = make_float2((u + v) * cosf(angle), (u - v) * sinf(angle)); + + /* rotate */ + rotation += corner * 2.0f * angle; + + float cr = cosf(rotation); + float sr = sinf(rotation); + + return make_float2(cr * p.x - sr * p.y, sr * p.x + cr * p.y); +} + +CCL_NAMESPACE_END |