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Diffstat (limited to 'intern/cycles/kernel/kernel_montecarlo.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_montecarlo.h | 308 |
1 files changed, 0 insertions, 308 deletions
diff --git a/intern/cycles/kernel/kernel_montecarlo.h b/intern/cycles/kernel/kernel_montecarlo.h deleted file mode 100644 index c931aa45276..00000000000 --- a/intern/cycles/kernel/kernel_montecarlo.h +++ /dev/null @@ -1,308 +0,0 @@ -/* - * 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); -} - -ccl_device float balance_heuristic(float a, float b) -{ - return (a) / (a + b); -} - -ccl_device float balance_heuristic_3(float a, float b, float c) -{ - return (a) / (a + b + c); -} - -ccl_device float power_heuristic(float a, float b) -{ - return (a * a) / (a * a + b * b); -} - -ccl_device float power_heuristic_3(float a, float b, float c) -{ - return (a * a) / (a * a + b * b + c * c); -} - -ccl_device float max_heuristic(float a, float b) -{ - return (a > b) ? 1.0f : 0.0f; -} - -/* 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_device float3 ensure_valid_reflection(float3 Ng, float3 I, float3 N) -{ - float3 R = 2 * dot(N, I) * N - I; - - /* Reflection rays may always be at least as shallow as the incoming ray. */ - float threshold = min(0.9f * dot(Ng, I), 0.01f); - if (dot(Ng, R) >= threshold) { - return N; - } - - /* Form coordinate system with Ng as the Z axis and N inside the X-Z-plane. - * The X axis is found by normalizing the component of N that's orthogonal to Ng. - * The Y axis isn't actually needed. - */ - float NdotNg = dot(N, Ng); - float3 X = normalize(N - NdotNg * Ng); - - /* Keep math expressions. */ - /* clang-format off */ - /* Calculate N.z and N.x in the local coordinate system. - * - * The goal of this computation is to find a N' that is rotated towards Ng just enough - * to lift R' above the threshold (here called t), therefore dot(R', Ng) = t. - * - * According to the standard reflection equation, - * this means that we want dot(2*dot(N', I)*N' - I, Ng) = t. - * - * Since the Z axis of our local coordinate system is Ng, dot(x, Ng) is just x.z, so we get - * 2*dot(N', I)*N'.z - I.z = t. - * - * The rotation is simple to express in the coordinate system we formed - - * since N lies in the X-Z-plane, we know that N' will also lie in the X-Z-plane, - * so N'.y = 0 and therefore dot(N', I) = N'.x*I.x + N'.z*I.z . - * - * Furthermore, we want N' to be normalized, so N'.x = sqrt(1 - N'.z^2). - * - * With these simplifications, - * we get the final equation 2*(sqrt(1 - N'.z^2)*I.x + N'.z*I.z)*N'.z - I.z = t. - * - * The only unknown here is N'.z, so we can solve for that. - * - * The equation has four solutions in general: - * - * N'.z = +-sqrt(0.5*(+-sqrt(I.x^2*(I.x^2 + I.z^2 - t^2)) + t*I.z + I.x^2 + I.z^2)/(I.x^2 + I.z^2)) - * We can simplify this expression a bit by grouping terms: - * - * a = I.x^2 + I.z^2 - * b = sqrt(I.x^2 * (a - t^2)) - * c = I.z*t + a - * N'.z = +-sqrt(0.5*(+-b + c)/a) - * - * Two solutions can immediately be discarded because they're negative so N' would lie in the - * lower hemisphere. - */ - /* clang-format on */ - - float Ix = dot(I, X), Iz = dot(I, Ng); - float Ix2 = sqr(Ix), Iz2 = sqr(Iz); - float a = Ix2 + Iz2; - - float b = safe_sqrtf(Ix2 * (a - sqr(threshold))); - float c = Iz * threshold + a; - - /* Evaluate both solutions. - * In many cases one can be immediately discarded (if N'.z would be imaginary or larger than - * one), so check for that first. If no option is viable (might happen in extreme cases like N - * being in the wrong hemisphere), give up and return Ng. */ - float fac = 0.5f / a; - float N1_z2 = fac * (b + c), N2_z2 = fac * (-b + c); - bool valid1 = (N1_z2 > 1e-5f) && (N1_z2 <= (1.0f + 1e-5f)); - bool valid2 = (N2_z2 > 1e-5f) && (N2_z2 <= (1.0f + 1e-5f)); - - float2 N_new; - if (valid1 && valid2) { - /* If both are possible, do the expensive reflection-based check. */ - float2 N1 = make_float2(safe_sqrtf(1.0f - N1_z2), safe_sqrtf(N1_z2)); - float2 N2 = make_float2(safe_sqrtf(1.0f - N2_z2), safe_sqrtf(N2_z2)); - - float R1 = 2 * (N1.x * Ix + N1.y * Iz) * N1.y - Iz; - float R2 = 2 * (N2.x * Ix + N2.y * Iz) * N2.y - Iz; - - valid1 = (R1 >= 1e-5f); - valid2 = (R2 >= 1e-5f); - if (valid1 && valid2) { - /* If both solutions are valid, return the one with the shallower reflection since it will be - * closer to the input (if the original reflection wasn't shallow, we would not be in this - * part of the function). */ - N_new = (R1 < R2) ? N1 : N2; - } - else { - /* If only one reflection is valid (= positive), pick that one. */ - N_new = (R1 > R2) ? N1 : N2; - } - } - else if (valid1 || valid2) { - /* Only one solution passes the N'.z criterium, so pick that one. */ - float Nz2 = valid1 ? N1_z2 : N2_z2; - N_new = make_float2(safe_sqrtf(1.0f - Nz2), safe_sqrtf(Nz2)); - } - else { - return Ng; - } - - return N_new.x * X + N_new.y * Ng; -} - -CCL_NAMESPACE_END |