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Diffstat (limited to 'intern/cycles/kernel/kernel_light_common.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_light_common.h | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/intern/cycles/kernel/kernel_light_common.h b/intern/cycles/kernel/kernel_light_common.h new file mode 100644 index 00000000000..39503a4b479 --- /dev/null +++ b/intern/cycles/kernel/kernel_light_common.h @@ -0,0 +1,159 @@ +/* + * Copyright 2011-2020 Blender Foundation + * + * 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 + +/* Area light sampling */ + +/* Uses the following paper: + * + * Carlos Urena et al. + * An Area-Preserving Parametrization for Spherical Rectangles. + * + * https://www.solidangle.com/research/egsr2013_spherical_rectangle.pdf + * + * Note: light_p is modified when sample_coord is true. + */ +ccl_device_inline float rect_light_sample(float3 P, + float3 *light_p, + float3 axisu, + float3 axisv, + float randu, + float randv, + bool sample_coord) +{ + /* In our name system we're using P for the center, + * which is o in the paper. + */ + + float3 corner = *light_p - axisu * 0.5f - axisv * 0.5f; + float axisu_len, axisv_len; + /* Compute local reference system R. */ + float3 x = normalize_len(axisu, &axisu_len); + float3 y = normalize_len(axisv, &axisv_len); + float3 z = cross(x, y); + /* Compute rectangle coords in local reference system. */ + float3 dir = corner - P; + float z0 = dot(dir, z); + /* Flip 'z' to make it point against Q. */ + if (z0 > 0.0f) { + z *= -1.0f; + z0 *= -1.0f; + } + float x0 = dot(dir, x); + float y0 = dot(dir, y); + float x1 = x0 + axisu_len; + float y1 = y0 + axisv_len; + /* Compute internal angles (gamma_i). */ + float4 diff = make_float4(x0, y1, x1, y0) - make_float4(x1, y0, x0, y1); + float4 nz = make_float4(y0, x1, y1, x0) * diff; + nz = nz / sqrt(z0 * z0 * diff * diff + nz * nz); + float g0 = safe_acosf(-nz.x * nz.y); + float g1 = safe_acosf(-nz.y * nz.z); + float g2 = safe_acosf(-nz.z * nz.w); + float g3 = safe_acosf(-nz.w * nz.x); + /* Compute predefined constants. */ + float b0 = nz.x; + float b1 = nz.z; + float b0sq = b0 * b0; + float k = M_2PI_F - g2 - g3; + /* Compute solid angle from internal angles. */ + float S = g0 + g1 - k; + + if (sample_coord) { + /* Compute cu. */ + float au = randu * S + k; + float fu = (cosf(au) * b0 - b1) / sinf(au); + float cu = 1.0f / sqrtf(fu * fu + b0sq) * (fu > 0.0f ? 1.0f : -1.0f); + cu = clamp(cu, -1.0f, 1.0f); + /* Compute xu. */ + float xu = -(cu * z0) / max(sqrtf(1.0f - cu * cu), 1e-7f); + xu = clamp(xu, x0, x1); + /* Compute yv. */ + float z0sq = z0 * z0; + float y0sq = y0 * y0; + float y1sq = y1 * y1; + float d = sqrtf(xu * xu + z0sq); + float h0 = y0 / sqrtf(d * d + y0sq); + float h1 = y1 / sqrtf(d * d + y1sq); + float hv = h0 + randv * (h1 - h0), hv2 = hv * hv; + float yv = (hv2 < 1.0f - 1e-6f) ? (hv * d) / sqrtf(1.0f - hv2) : y1; + + /* Transform (xu, yv, z0) to world coords. */ + *light_p = P + xu * x + yv * y + z0 * z; + } + + /* return pdf */ + if (S != 0.0f) + return 1.0f / S; + else + return 0.0f; +} + +ccl_device_inline float3 ellipse_sample(float3 ru, float3 rv, float randu, float randv) +{ + to_unit_disk(&randu, &randv); + return ru * randu + rv * randv; +} + +ccl_device float3 disk_light_sample(float3 v, float randu, float randv) +{ + float3 ru, rv; + + make_orthonormals(v, &ru, &rv); + + return ellipse_sample(ru, rv, randu, randv); +} + +ccl_device float3 distant_light_sample(float3 D, float radius, float randu, float randv) +{ + return normalize(D + disk_light_sample(D, randu, randv) * radius); +} + +ccl_device float3 +sphere_light_sample(float3 P, float3 center, float radius, float randu, float randv) +{ + return disk_light_sample(normalize(P - center), randu, randv) * radius; +} + +ccl_device float spot_light_attenuation(float3 dir, float spot_angle, float spot_smooth, float3 N) +{ + float attenuation = dot(dir, N); + + if (attenuation <= spot_angle) { + attenuation = 0.0f; + } + else { + float t = attenuation - spot_angle; + + if (t < spot_smooth && spot_smooth != 0.0f) + attenuation *= smoothstepf(t / spot_smooth); + } + + return attenuation; +} + +ccl_device float lamp_light_pdf(KernelGlobals *kg, const float3 Ng, const float3 I, float t) +{ + float cos_pi = dot(Ng, I); + + if (cos_pi <= 0.0f) + return 0.0f; + + return t * t / cos_pi; +} + +CCL_NAMESPACE_END |