diff options
Diffstat (limited to 'intern/cycles/kernel/kernel_differential.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_differential.h | 132 |
1 files changed, 71 insertions, 61 deletions
diff --git a/intern/cycles/kernel/kernel_differential.h b/intern/cycles/kernel/kernel_differential.h index 924d96c72e5..8513de0d843 100644 --- a/intern/cycles/kernel/kernel_differential.h +++ b/intern/cycles/kernel/kernel_differential.h @@ -18,88 +18,98 @@ CCL_NAMESPACE_BEGIN /* See "Tracing Ray Differentials", Homan Igehy, 1999. */ -ccl_device void differential_transfer(ccl_addr_space differential3 *dP_, const differential3 dP, float3 D, const differential3 dD, float3 Ng, float t) +ccl_device void differential_transfer(ccl_addr_space differential3 *dP_, + const differential3 dP, + float3 D, + const differential3 dD, + float3 Ng, + float t) { - /* ray differential transfer through homogeneous medium, to - * compute dPdx/dy at a shading point from the incoming ray */ + /* ray differential transfer through homogeneous medium, to + * compute dPdx/dy at a shading point from the incoming ray */ - float3 tmp = D/dot(D, Ng); - float3 tmpx = dP.dx + t*dD.dx; - float3 tmpy = dP.dy + t*dD.dy; + float3 tmp = D / dot(D, Ng); + float3 tmpx = dP.dx + t * dD.dx; + float3 tmpy = dP.dy + t * dD.dy; - dP_->dx = tmpx - dot(tmpx, Ng)*tmp; - dP_->dy = tmpy - dot(tmpy, Ng)*tmp; + dP_->dx = tmpx - dot(tmpx, Ng) * tmp; + dP_->dy = tmpy - dot(tmpy, Ng) * tmp; } ccl_device void differential_incoming(ccl_addr_space differential3 *dI, const differential3 dD) { - /* compute dIdx/dy at a shading point, we just need to negate the - * differential of the ray direction */ + /* compute dIdx/dy at a shading point, we just need to negate the + * differential of the ray direction */ - dI->dx = -dD.dx; - dI->dy = -dD.dy; + dI->dx = -dD.dx; + dI->dy = -dD.dy; } -ccl_device void differential_dudv(ccl_addr_space differential *du, ccl_addr_space differential *dv, float3 dPdu, float3 dPdv, differential3 dP, float3 Ng) +ccl_device void differential_dudv(ccl_addr_space differential *du, + ccl_addr_space differential *dv, + float3 dPdu, + float3 dPdv, + differential3 dP, + float3 Ng) { - /* now we have dPdx/dy from the ray differential transfer, and dPdu/dv - * from the primitive, we can compute dudx/dy and dvdx/dy. these are - * mainly used for differentials of arbitrary mesh attributes. */ - - /* find most stable axis to project to 2D */ - float xn = fabsf(Ng.x); - float yn = fabsf(Ng.y); - float zn = fabsf(Ng.z); - - if(zn < xn || zn < yn) { - if(yn < xn || yn < zn) { - dPdu.x = dPdu.y; - dPdv.x = dPdv.y; - dP.dx.x = dP.dx.y; - dP.dy.x = dP.dy.y; - } - - dPdu.y = dPdu.z; - dPdv.y = dPdv.z; - dP.dx.y = dP.dx.z; - dP.dy.y = dP.dy.z; - } - - /* using Cramer's rule, we solve for dudx and dvdx in a 2x2 linear system, - * and the same for dudy and dvdy. the denominator is the same for both - * solutions, so we compute it only once. - * - * dP.dx = dPdu * dudx + dPdv * dvdx; - * dP.dy = dPdu * dudy + dPdv * dvdy; */ - - float det = (dPdu.x*dPdv.y - dPdv.x*dPdu.y); - - if(det != 0.0f) - det = 1.0f/det; - - du->dx = (dP.dx.x*dPdv.y - dP.dx.y*dPdv.x)*det; - dv->dx = (dP.dx.y*dPdu.x - dP.dx.x*dPdu.y)*det; - - du->dy = (dP.dy.x*dPdv.y - dP.dy.y*dPdv.x)*det; - dv->dy = (dP.dy.y*dPdu.x - dP.dy.x*dPdu.y)*det; + /* now we have dPdx/dy from the ray differential transfer, and dPdu/dv + * from the primitive, we can compute dudx/dy and dvdx/dy. these are + * mainly used for differentials of arbitrary mesh attributes. */ + + /* find most stable axis to project to 2D */ + float xn = fabsf(Ng.x); + float yn = fabsf(Ng.y); + float zn = fabsf(Ng.z); + + if (zn < xn || zn < yn) { + if (yn < xn || yn < zn) { + dPdu.x = dPdu.y; + dPdv.x = dPdv.y; + dP.dx.x = dP.dx.y; + dP.dy.x = dP.dy.y; + } + + dPdu.y = dPdu.z; + dPdv.y = dPdv.z; + dP.dx.y = dP.dx.z; + dP.dy.y = dP.dy.z; + } + + /* using Cramer's rule, we solve for dudx and dvdx in a 2x2 linear system, + * and the same for dudy and dvdy. the denominator is the same for both + * solutions, so we compute it only once. + * + * dP.dx = dPdu * dudx + dPdv * dvdx; + * dP.dy = dPdu * dudy + dPdv * dvdy; */ + + float det = (dPdu.x * dPdv.y - dPdv.x * dPdu.y); + + if (det != 0.0f) + det = 1.0f / det; + + du->dx = (dP.dx.x * dPdv.y - dP.dx.y * dPdv.x) * det; + dv->dx = (dP.dx.y * dPdu.x - dP.dx.x * dPdu.y) * det; + + du->dy = (dP.dy.x * dPdv.y - dP.dy.y * dPdv.x) * det; + dv->dy = (dP.dy.y * dPdu.x - dP.dy.x * dPdu.y) * det; } ccl_device differential differential_zero() { - differential d; - d.dx = 0.0f; - d.dy = 0.0f; + differential d; + d.dx = 0.0f; + d.dy = 0.0f; - return d; + return d; } ccl_device differential3 differential3_zero() { - differential3 d; - d.dx = make_float3(0.0f, 0.0f, 0.0f); - d.dy = make_float3(0.0f, 0.0f, 0.0f); + differential3 d; + d.dx = make_float3(0.0f, 0.0f, 0.0f); + d.dy = make_float3(0.0f, 0.0f, 0.0f); - return d; + return d; } CCL_NAMESPACE_END |