void sreFrustum::CalculateShadowCasterVolume(const Vector4D& lightpos, int nu_frustum_planes) { nu_frustum_planes = maxf(nu_frustum_planes, SRE_NU_FRUSTUM_PLANES); // Note: for beam lights, this might be inaccurate. if (lightpos.w == 1.0f && Intersects(lightpos.GetPoint3D(), frustum_world)) { // If the point light position is inside the view frustum, we only need to consider the // set of visible objects. shadow_caster_volume.nu_planes = nu_frustum_planes; for (int i = 0; i < nu_frustum_planes; i++) shadow_caster_volume.plane[i] = frustum_world.plane[i]; goto end; } // Calculate the convex hull enclosing the view frustum and the light source. shadow_caster_volume.nu_planes = 0; // Calculate the dot products between the frustum planes and the light source. float dot[6] DST_ALIGNED(16); // The SIMD-accelerated version check for 16-bytes aligned arrays, which is hard to // guarantee in this case; otherwise, no SIMD will be used. #if 1 dstCalculateDotProductsNx1(nu_frustum_planes, &frustum_world.plane[0], lightpos, &dot[0]); #else for (int i = 0; i < nu_frustum_planes; i++) dot[i] = Dot(frustum_world.plane[i], lightpos); #endif // For each frustum plane, add it if it is part of the convex hull. for (int i = 0; i < nu_frustum_planes; i++) if (dot[i] > 0) { shadow_caster_volume.plane[shadow_caster_volume.nu_planes] = frustum_world.plane[i]; shadow_caster_volume.nu_planes++; } // printf("Shadow caster volume planes: from frustum: %d\n", shadow_caster_volume.nu_planes); if (shadow_caster_volume.nu_planes == 0 && lightpos.w == 1.0f) { // Special case: the point light source is behind the camera and there is no far plane. // As a result, there is no plane from the frustum with a positive dot product. In // this case, construct a volume consisting of the lightsource and four planes parallel // to the frustum side planes but starting at the lightsource. for (int i = 0; i < 4; i++) { // Copy the normal. shadow_caster_volume.plane[i] = frustum_world.plane[i]; // Calculate the distance such that the lightsource is in the plane. shadow_caster_volume.plane[i].w = - Dot(frustum_world.plane[i].GetVector3D(), lightpos.GetPoint3D()); } shadow_caster_volume.nu_planes = 4; goto end; } // For each pair of adjacent frustum planes, if one has a positive dot product and the other // does not, calculate a new plane defined by the edge between those two frustum planes and // the position of the light source, making sure the plane's normal direction faces inward. // For directional lights, the plane runs parallel to the direction of the light. nu_shadow_caster_edges = 0; int n; if (nu_frustum_planes == 5) n = 8; else n = 12; for (int i = 0; i < n; i++) if ((dot[adjacent_plane[i].plane0] > 0 && dot[adjacent_plane[i].plane1] <= 0) || (dot[adjacent_plane[i].plane0] <= 0 && dot[adjacent_plane[i].plane1] > 0)) { // printf("Setting plane from adjacent planes %d and %d using frustum vertices %d and %d\n", // adjacent_plane[i].plane0, adjacent_plane[i].plane1, adjacent_plane[i].vertex0, // adjacent_plane[i].vertex1); if (lightpos.w == 1.0f) shadow_caster_volume.plane[shadow_caster_volume.nu_planes] = dstPlaneFromPoints( frustum_world.hull.vertex[adjacent_plane[i].vertex0], frustum_world.hull.vertex[adjacent_plane[i].vertex1], lightpos.GetPoint3D() ); else { shadow_caster_volume.plane[shadow_caster_volume.nu_planes] = dstPlaneFromPoints( frustum_world.hull.vertex[adjacent_plane[i].vertex0], frustum_world.hull.vertex[adjacent_plane[i].vertex1], frustum_world.hull.vertex[adjacent_plane[i].vertex0] + lightpos.GetVector3D() ); shadow_caster_edge[nu_shadow_caster_edges][0] = adjacent_plane[i].vertex0; shadow_caster_edge[nu_shadow_caster_edges][1] = adjacent_plane[i].vertex1; nu_shadow_caster_edges++; } // Make sure the normal is pointed inward, check by taking the dot product with the frustum // "centroid". shadow_caster_volume.plane[shadow_caster_volume.nu_planes].OrientPlaneTowardsPoint( frustum_world.sphere.center); shadow_caster_volume.nu_planes++; } end: ; #if 0 printf("Light (%lf, %lf, %lf, %lf), %d planes in shadow caster volume.\n", lightpos.x, lightpos.y, lightpos.z, lightpos.w, shadow_caster_volume.nu_planes); for (int i = 0; i < shadow_caster_volume.nu_planes; i++) printf("Plane %d: (%lf, %lf, %lf, %lf) ", i, shadow_caster_volume.plane[i].x, shadow_caster_volume.plane[i].y, shadow_caster_volume.plane[i].y, shadow_caster_volume.plane[i].w); printf("\n"); #endif }