| 64 |
|
{ |
| 65 |
|
The following forumulas compute Shirley-Chiu bin "scbin" based on: |
| 66 |
|
|
| 67 |
+ |
RHS - right-handed system (-1 for left-handed coords) |
| 68 |
|
Dx,Dy,Dz - Incident direction (normalized, towards surface front) |
| 69 |
< |
Nx,Ny,Nz - Surface normal (normalized, away from surface) |
| 69 |
> |
rNx,rNy,rNz - Surface normal (normalized, away from surface) |
| 70 |
|
Ux,Uy,Uz - Up direction vector (does not need to be normalized) |
| 71 |
|
|
| 72 |
|
The SCdim variable assigns the square side dimension for bins, which are |
| 73 |
|
ordered with the "up" direction changing fastest. |
| 74 |
|
} |
| 75 |
< |
|
| 75 |
> |
RHS = 1; |
| 76 |
|
{ Compute oriented axis values } |
| 77 |
< |
inc_dot = -Dx*Nx-Dy*Ny-Dz*Nz; |
| 78 |
< |
inc_rx = -Dx*(Uy*Nz-Uz*Ny) - Dy*(Uz*Nx-Ux*Nz) - Dz*(Ux*Ny-Uy*Nx); |
| 79 |
< |
inc_ry = -Dx*Ux-Dy*Uy-Dz*Uz - inc_dot*(Nx*Ux+Ny*Uy+Nz*Uz); |
| 77 |
> |
inc_dz = -Dx*rNx-Dy*rNy-Dz*rNz; |
| 78 |
> |
inc_rx = -RHS*(Dx*(Uy*rNz-Uz*rNy) + Dy*(Uz*rNx-Ux*rNz) + Dz*(Ux*rNy-Uy*rNx)); |
| 79 |
> |
inc_ry = -Dx*Ux-Dy*Uy-Dz*Uz - inc_dz*(rNx*Ux+rNy*Uy+rNz*Uz); |
| 80 |
|
inc_den2 = inc_rx*inc_rx + inc_ry*inc_ry; |
| 81 |
< |
inc_radf = if(inc_den2-1e-7, sqrt((1 - inc_dot*inc_dot)/inc_den2), 0); |
| 81 |
> |
inc_radf = if(inc_den2-1e-7, sqrt((1 - inc_dz*inc_dz)/inc_den2), 0); |
| 82 |
|
{ Pass to formulas in first section } |
| 83 |
|
in_disk_x = inc_rx*inc_radf; |
| 84 |
|
in_disk_y = inc_ry*inc_radf; |
| 85 |
|
{ Compute final bin (-1 if behind surface) } |
| 86 |
< |
scbin = if(inc_dot, |
| 86 |
> |
scbin = if(inc_dz, |
| 87 |
|
floor(out_square_x*SCdim)*SCdim + floor(out_square_y*SCdim), |
| 88 |
|
-1); |
