diff options
Diffstat (limited to 'intern/cycles/kernel/kernel_light.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_light.h | 411 |
1 files changed, 313 insertions, 98 deletions
diff --git a/intern/cycles/kernel/kernel_light.h b/intern/cycles/kernel/kernel_light.h index 76fa754b5fa..1badbc3b9f7 100644 --- a/intern/cycles/kernel/kernel_light.h +++ b/intern/cycles/kernel/kernel_light.h @@ -33,6 +33,98 @@ typedef struct LightSample { LightType type; /* type of light */ } LightSample; +/* 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 float area_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; + /* Create vectors to four vertices. */ + float3 v00 = make_float3(x0, y0, z0); + float3 v01 = make_float3(x0, y1, z0); + float3 v10 = make_float3(x1, y0, z0); + float3 v11 = make_float3(x1, y1, z0); + /* Compute normals to edges. */ + float3 n0 = normalize(cross(v00, v10)); + float3 n1 = normalize(cross(v10, v11)); + float3 n2 = normalize(cross(v11, v01)); + float3 n3 = normalize(cross(v01, v00)); + /* Compute internal angles (gamma_i). */ + float g0 = safe_acosf(-dot(n0, n1)); + float g1 = safe_acosf(-dot(n1, n2)); + float g2 = safe_acosf(-dot(n2, n3)); + float g3 = safe_acosf(-dot(n3, n0)); + /* Compute predefined constants. */ + float b0 = n0.z; + float b1 = n2.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) / sqrtf(1.0f - cu * cu); + 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; +} + /* Background Light */ #ifdef __BACKGROUND_MIS__ @@ -46,7 +138,7 @@ ccl_device_noinline #else ccl_device #endif -float3 background_light_sample(KernelGlobals *kg, float randu, float randv, float *pdf) +float3 background_map_sample(KernelGlobals *kg, float randu, float randv, float *pdf) { /* for the following, the CDF values are actually a pair of floats, with the * function value as X and the actual CDF as Y. The last entry's function @@ -116,10 +208,8 @@ float3 background_light_sample(KernelGlobals *kg, float randu, float randv, floa else *pdf = (cdf_u.x * cdf_v.x)/(M_2PI_F * M_PI_F * sin_theta * denom); - *pdf *= kernel_data.integrator.pdf_lights; - /* compute direction */ - return -equirectangular_to_direction(u, v); + return equirectangular_to_direction(u, v); } /* TODO(sergey): Same as above, after the release we should consider using @@ -130,7 +220,7 @@ ccl_device_noinline #else ccl_device #endif -float background_light_pdf(KernelGlobals *kg, float3 direction) +float background_map_pdf(KernelGlobals *kg, float3 direction) { float2 uv = direction_to_equirectangular(direction); int res = kernel_data.integrator.pdf_background_res; @@ -156,9 +246,223 @@ float background_light_pdf(KernelGlobals *kg, float3 direction) float2 cdf_u = kernel_tex_fetch(__light_background_conditional_cdf, index_v * (res + 1) + index_u); float2 cdf_v = kernel_tex_fetch(__light_background_marginal_cdf, index_v); - float pdf = (cdf_u.x * cdf_v.x)/(M_2PI_F * M_PI_F * sin_theta * denom); + return (cdf_u.x * cdf_v.x)/(M_2PI_F * M_PI_F * sin_theta * denom); +} + +ccl_device_inline bool background_portal_data_fetch_and_check_side(KernelGlobals *kg, + float3 P, + int index, + float3 *lightpos, + float3 *dir) +{ + float4 data0 = kernel_tex_fetch(__light_data, (index + kernel_data.integrator.portal_offset)*LIGHT_SIZE + 0); + float4 data3 = kernel_tex_fetch(__light_data, (index + kernel_data.integrator.portal_offset)*LIGHT_SIZE + 3); + + *lightpos = make_float3(data0.y, data0.z, data0.w); + *dir = make_float3(data3.y, data3.z, data3.w); + + /* Check whether portal is on the right side. */ + if(dot(*dir, P - *lightpos) > 1e-5f) + return true; + + return false; +} + +ccl_device float background_portal_pdf(KernelGlobals *kg, + float3 P, + float3 direction, + int ignore_portal, + bool *is_possible) +{ + float portal_pdf = 0.0f; + + for(int p = 0; p < kernel_data.integrator.num_portals; p++) { + if(p == ignore_portal) + continue; + + float3 lightpos, dir; + if(!background_portal_data_fetch_and_check_side(kg, P, p, &lightpos, &dir)) + continue; + + if(is_possible) { + /* There's a portal that could be sampled from this position. */ + *is_possible = true; + } + + float t = -(dot(P, dir) - dot(lightpos, dir)) / dot(direction, dir); + if(t <= 1e-5f) { + /* Either behind the portal or too close. */ + continue; + } - return pdf * kernel_data.integrator.pdf_lights; + float4 data1 = kernel_tex_fetch(__light_data, (p + kernel_data.integrator.portal_offset)*LIGHT_SIZE + 1); + float4 data2 = kernel_tex_fetch(__light_data, (p + kernel_data.integrator.portal_offset)*LIGHT_SIZE + 2); + + float3 axisu = make_float3(data1.y, data1.z, data1.w); + float3 axisv = make_float3(data2.y, data2.z, data2.w); + + float3 hit = P + t*direction; + float3 inplane = hit - lightpos; + /* Skip if the the ray doesn't pass through portal. */ + if(fabsf(dot(inplane, axisu) / dot(axisu, axisu)) > 0.5f) + continue; + if(fabsf(dot(inplane, axisv) / dot(axisv, axisv)) > 0.5f) + continue; + + portal_pdf += area_light_sample(P, &lightpos, axisu, axisv, 0.0f, 0.0f, false); + } + + return kernel_data.integrator.num_portals? portal_pdf / kernel_data.integrator.num_portals: 0.0f; +} + +ccl_device int background_num_possible_portals(KernelGlobals *kg, float3 P) +{ + int num_possible_portals = 0; + for(int p = 0; p < kernel_data.integrator.num_portals; p++) { + float3 lightpos, dir; + if(background_portal_data_fetch_and_check_side(kg, P, p, &lightpos, &dir)) + num_possible_portals++; + } + return num_possible_portals; +} + +ccl_device float3 background_portal_sample(KernelGlobals *kg, + float3 P, + float randu, + float randv, + int num_possible, + int *sampled_portal, + float *pdf) +{ + /* Pick a portal, then re-normalize randv. */ + randv *= num_possible; + int portal = (int)randv; + randv -= portal; + + /* TODO(sergey): Some smarter way of finding portal to sample + * is welcome. + */ + for(int p = 0; p < kernel_data.integrator.num_portals; p++) { + /* Search for the sampled portal. */ + float3 lightpos, dir; + if(!background_portal_data_fetch_and_check_side(kg, P, p, &lightpos, &dir)) + continue; + + if(portal == 0) { + /* p is the portal to be sampled. */ + float4 data1 = kernel_tex_fetch(__light_data, (p + kernel_data.integrator.portal_offset)*LIGHT_SIZE + 1); + float4 data2 = kernel_tex_fetch(__light_data, (p + kernel_data.integrator.portal_offset)*LIGHT_SIZE + 2); + float3 axisu = make_float3(data1.y, data1.z, data1.w); + float3 axisv = make_float3(data2.y, data2.z, data2.w); + + *pdf = area_light_sample(P, &lightpos, + axisu, axisv, + randu, randv, + true); + + *pdf /= num_possible; + *sampled_portal = p; + return normalize(lightpos - P); + } + + portal--; + } + + return make_float3(0.0f, 0.0f, 0.0f); +} + +ccl_device float3 background_light_sample(KernelGlobals *kg, float3 P, float randu, float randv, float *pdf) +{ + /* Probability of sampling portals instead of the map. */ + float portal_sampling_pdf = kernel_data.integrator.portal_pdf; + + /* Check if there are portals in the scene which we can sample. */ + if(portal_sampling_pdf > 0.0f) { + int num_portals = background_num_possible_portals(kg, P); + if(num_portals > 0) { + if(portal_sampling_pdf == 1.0f || randu < portal_sampling_pdf) { + if(portal_sampling_pdf < 1.0f) { + randu /= portal_sampling_pdf; + } + int portal; + float3 D = background_portal_sample(kg, P, randu, randv, num_portals, &portal, pdf); + if(num_portals > 1) { + /* Ignore the chosen portal, its pdf is already included. */ + *pdf += background_portal_pdf(kg, P, D, portal, NULL); + } + /* We could also have sampled the map, so combine with MIS. */ + if(portal_sampling_pdf < 1.0f) { + float cdf_pdf = background_map_pdf(kg, D); + *pdf = (portal_sampling_pdf * (*pdf) + + (1.0f - portal_sampling_pdf) * cdf_pdf); + } + return D; + } else { + /* Sample map, but with nonzero portal_sampling_pdf for MIS. */ + randu = (randu - portal_sampling_pdf) / (1.0f - portal_sampling_pdf); + } + } else { + /* We can't sample a portal. + * Check if we can sample the map instead. + */ + if(portal_sampling_pdf == 1.0f) { + /* Use uniform as a fallback if we can't sample the map. */ + *pdf = 1.0f / M_4PI_F; + return sample_uniform_sphere(randu, randv); + } + else { + portal_sampling_pdf = 0.0f; + } + } + } + + float3 D = background_map_sample(kg, randu, randv, pdf); + /* Use MIS if portals could be sampled as well. */ + if(portal_sampling_pdf > 0.0f) { + float portal_pdf = background_portal_pdf(kg, P, D, -1, NULL); + *pdf = (portal_sampling_pdf * portal_pdf + + (1.0f - portal_sampling_pdf) * (*pdf)); + } + return D; +} + +ccl_device float background_light_pdf(KernelGlobals *kg, float3 P, float3 direction) +{ + /* Probability of sampling portals instead of the map. */ + float portal_sampling_pdf = kernel_data.integrator.portal_pdf; + + if(portal_sampling_pdf > 0.0f) { + bool is_possible = false; + float portal_pdf = background_portal_pdf(kg, P, direction, -1, &is_possible); + if(portal_pdf == 0.0f) { + if(portal_sampling_pdf == 1.0f) { + /* If there are no possible portals at this point, + * the fallback sampling would have been used. + * Otherwise, the direction would not be sampled at all => pdf = 0 + */ + return is_possible? 0.0f: kernel_data.integrator.pdf_lights / M_4PI_F; + } + else { + /* We can only sample the map. */ + return background_map_pdf(kg, direction) * kernel_data.integrator.pdf_lights; + } + } else { + if(portal_sampling_pdf == 1.0f) { + /* We can only sample portals. */ + return portal_pdf * kernel_data.integrator.pdf_lights; + } + else { + /* We can sample both, so combine with MIS. */ + return (background_map_pdf(kg, direction) * (1.0f - portal_sampling_pdf) + + portal_pdf * portal_sampling_pdf) * kernel_data.integrator.pdf_lights; + } + } + } + + /* No portals in the scene, so must sample the map. + * At least one of them is always possible if we have a LIGHT_BACKGROUND. + */ + return background_map_pdf(kg, direction) * kernel_data.integrator.pdf_lights; } #endif @@ -184,96 +488,6 @@ ccl_device float3 sphere_light_sample(float3 P, float3 center, float radius, flo return disk_light_sample(normalize(P - center), randu, randv)*radius; } -/* 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 float area_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; - /* Create vectors to four vertices. */ - float3 v00 = make_float3(x0, y0, z0); - float3 v01 = make_float3(x0, y1, z0); - float3 v10 = make_float3(x1, y0, z0); - float3 v11 = make_float3(x1, y1, z0); - /* Compute normals to edges. */ - float3 n0 = normalize(cross(v00, v10)); - float3 n1 = normalize(cross(v10, v11)); - float3 n2 = normalize(cross(v11, v01)); - float3 n3 = normalize(cross(v01, v00)); - /* Compute internal angles (gamma_i). */ - float g0 = safe_acosf(-dot(n0, n1)); - float g1 = safe_acosf(-dot(n1, n2)); - float g2 = safe_acosf(-dot(n2, n3)); - float g3 = safe_acosf(-dot(n3, n0)); - /* Compute predefined constants. */ - float b0 = n0.z; - float b1 = n2.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) / sqrtf(1.0f - cu * cu); - 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 float spot_light_attenuation(float4 data1, float4 data2, LightSample *ls) { float3 dir = make_float3(data2.y, data2.z, data2.w); @@ -344,13 +558,14 @@ ccl_device void lamp_light_sample(KernelGlobals *kg, int lamp, #ifdef __BACKGROUND_MIS__ else if(type == LIGHT_BACKGROUND) { /* infinite area light (e.g. light dome or env light) */ - float3 D = background_light_sample(kg, randu, randv, &ls->pdf); + float3 D = -background_light_sample(kg, P, randu, randv, &ls->pdf); ls->P = D; ls->Ng = D; ls->D = -D; ls->t = FLT_MAX; ls->eval_fac = 1.0f; + ls->pdf *= kernel_data.integrator.pdf_lights; } #endif else { |