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Cycles: Implement tricubic b-spline interpolation for CPU texture_image 

This is the first step towards supporting cubic interpolation for voxel
data (such as smoke and fire). It is not epxosed to the interface at all
yet, this is to be done soon after this change.
This commit is contained in:
Sergey Sharybin 2014-10-22 17:43:33 +06:00
parent ba7e504448
commit c24698a37e
1 changed files with 88 additions and 1 deletions
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89
intern/cycles/kernel/kernel_compat_cpu.h
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@ -174,7 +174,7 @@ template<typename T> struct texture_image {
return read(data[ix + iy*width + iz*width*height]);
}
else {
else if(interpolation == INTERPOLATION_LINEAR) {
float tx = frac(x*(float)width - 0.5f, &ix);
float ty = frac(y*(float)height - 0.5f, &iy);
float tz = frac(z*(float)depth - 0.5f, &iz);
@ -212,6 +212,93 @@ template<typename T> struct texture_image {
return r;
}
else {
/* Tricubic b-spline interpolation. */
const float tx = frac(x*(float)width - 0.5f, &ix);
const float ty = frac(y*(float)height - 0.5f, &iy);
const float tz = frac(z*(float)depth - 0.5f, &iz);
int pix, piy, piz, nnix, nniy, nniz;
if(periodic) {
ix = wrap_periodic(ix, width);
iy = wrap_periodic(iy, height);
iz = wrap_periodic(iz, depth);
pix = wrap_periodic(ix-1, width);
piy = wrap_periodic(iy-1, height);
piz = wrap_periodic(iz-1, depth);
nix = wrap_periodic(ix+1, width);
niy = wrap_periodic(iy+1, height);
niz = wrap_periodic(iz+1, depth);
nnix = wrap_periodic(ix+2, width);
nniy = wrap_periodic(iy+2, height);
nniz = wrap_periodic(iz+2, depth);
}
else {
ix = wrap_clamp(ix, width);
iy = wrap_clamp(iy, height);
iz = wrap_clamp(iz, depth);
pix = wrap_clamp(ix-1, width);
piy = wrap_clamp(iy-1, height);
piz = wrap_clamp(iz-1, depth);
nix = wrap_clamp(ix+1, width);
niy = wrap_clamp(iy+1, height);
niz = wrap_clamp(iz+1, depth);
nnix = wrap_clamp(ix+2, width);
nniy = wrap_clamp(iy+2, height);
nniz = wrap_clamp(iz+2, depth);
}
const int xc[4] = {pix, ix, nix, nnix};
const int yc[4] = {width * piy,
width * iy,
width * niy,
width * nniy};
const int zc[4] = {width * height * piz,
width * height * iz,
width * height * niz,
width * height * nniz};
float u[4], v[4], w[4];
/* Some helper macro to keep code reasonable size,
* let compiler to inline all the matrix multiplications.
*/
#define SET_SPLINE_WEIGHTS(u, t) \
{ \
u[0] = (((-1.0f/6.0f)* t + 0.5f) * t - 0.5f) * t + (1.0f/6.0f); \
u[1] = (( 0.5f * t - 1.0f) * t ) * t + (2.0f/3.0f); \
u[2] = (( -0.5f * t + 0.5f) * t + 0.5f) * t + (1.0f/6.0f); \
u[3] = (1.0f / 6.0f) * t * t * t; \
} (void)0
#define DATA(x, y, z) (read(data[xc[x] + yc[y] + zc[z]]))
#define COL_TERM(col, row) \
(v[col] * (u[0] * DATA(0, col, row) + \
u[1] * DATA(1, col, row) + \
u[2] * DATA(2, col, row) + \
u[3] * DATA(3, col, row)))
#define ROW_TERM(row) \
(w[row] * (COL_TERM(0, row) + \
COL_TERM(1, row) + \
COL_TERM(2, row) + \
COL_TERM(3, row)))
SET_SPLINE_WEIGHTS(u, tx);
SET_SPLINE_WEIGHTS(v, ty);
SET_SPLINE_WEIGHTS(w, tz);
/* Actual interpolation. */
return ROW_TERM(0) + ROW_TERM(1) + ROW_TERM(2) + ROW_TERM(3);
#undef COL_TERM
#undef ROW_TERM
#undef DATA
#undef SET_SPLINE_WEIGHTS
}
}
ccl_always_inline void dimensions_set(int width_, int height_, int depth_)