/*
* Copyright 1993-2007 NVIDIA Corporation. All rights reserved.
*
* NOTICE TO USER:
*
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* in individual and commercial software.
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* U.S. Government End Users. This source code is a "commercial item" as
* that term is defined at 48 C.F.R. 2.101 (OCT 1995), consisting of
* "commercial computer software" and "commercial computer software
* documentation" as such terms are used in 48 C.F.R. 12.212 (SEPT 1995)
* and is provided to the U.S. Government only as a commercial end item.
* Consistent with 48 C.F.R.12.212 and 48 C.F.R. 227.7202-1 through
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* source code with only those rights set forth herein.
*
* Any use of this source code in individual and commercial software must
* include, in the user documentation and internal comments to the code,
* the above Disclaimer and U.S. Government End Users Notice.
*/
#include <stdio.h>
#include <stdlib.h>
#include "fluidsGL_kernels.h"
// Texture reference for reading velocity field
texture<float2, 2> texref;
static cudaArray *array = NULL;
void setupTexture(int x, int y) {
// Wrap mode appears to be the new default
texref.filterMode = cudaFilterModeLinear;
cudaChannelFormatDesc desc = cudaCreateChannelDesc<float2>();
cudaMallocArray(&array, &desc, y, x);
cutilCheckMsg("cudaMalloc failed");
}
void bindTexture(void) {
cudaBindTextureToArray(texref, array);
cutilCheckMsg("cudaBindTexture failed");
}
void unbindTexture(void) {
cudaUnbindTexture(texref);
cutilCheckMsg("cudaUnbindTexture failed");
}
void updateTexture(cData *data, size_t wib, size_t h, size_t pitch) {
cudaMemcpy2DToArray(array, 0, 0, data, pitch, wib, h, cudaMemcpyDeviceToDevice);
cutilCheckMsg("cudaMemcpy failed");
}
void deleteTexture(void) {
cudaFreeArray(array);
cutilCheckMsg("cudaFreeArray failed");
}
// Note that these kernels are designed to work with arbitrary
// domain sizes, not just domains that are multiples of the tile
// size. Therefore, we have extra code that checks to make sure
// a given thread location falls within the domain boundaries in
// both X and Y. Also, the domain is covered by looping over
// multiple elements in the Y direction, while there is a one-to-one
// mapping between threads in X and the tile size in X.
// Nolan Goodnight 9/22/06
// This method adds constant force vectors to the velocity field
// stored in 'v' according to v(x,t+1) = v(x,t) + dt * f.
__global__ void
addForces_k(cData *v, int dx, int dy, int spx, int spy, float fx, float fy, int r, size_t pitch) {
int tx = threadIdx.x;
int ty = threadIdx.y;
cData *fj = (cData*)((char*)v + (ty + spy) * pitch) + tx + spx;
cData vterm = *fj;
tx -= r; ty -= r;
float s = 1.f / (1.f + tx*tx*tx*tx + ty*ty*ty*ty);
vterm.x += s * fx;
vterm.y += s * fy;
*fj = vterm;
}
// This method performs the velocity advection step, where we
// trace velocity vectors back in time to update each grid cell.
// That is, v(x,t+1) = v(p(x,-dt),t). Here we perform bilinear
// interpolation in the velocity space.
__global__ void
advectVelocity_k(cData *v, float *vx, float *vy,
int dx, int pdx, int dy, float dt, int lb) {
int gtidx = blockIdx.x * blockDim.x + threadIdx.x;
int gtidy = blockIdx.y * (lb * blockDim.y) + threadIdx.y * lb;
int p;
cData vterm, ploc;
float vxterm, vyterm;
// gtidx is the domain location in x for this thread
if (gtidx < dx) {
for (p = 0; p < lb; p++) {
// fi is the domain location in y for this thread
int fi = gtidy + p;
if (fi < dy) {
int fj = fi * pdx + gtidx;
vterm = tex2D(texref, (float)gtidx, (float)fi);
ploc.x = (gtidx + 0.5f) - (dt * vterm.x * dx);
ploc.y = (fi + 0.5f) - (dt * vterm.y * dy);
vterm = tex2D(texref, ploc.x, ploc.y);
vxterm = vterm.x; vyterm = vterm.y;
vx[fj] = vxterm;
vy[fj] = vyterm;
}
}
}
}
// This method performs velocity diffusion and forces mass conservation
// in the frequency domain. The inputs 'vx' and 'vy' are complex-valued
// arrays holding the Fourier coefficients of the velocity field in
// X and Y. Diffusion in this space takes a simple form described as:
// v(k,t) = v(k,t) / (1 + visc * dt * k^2), where visc is the viscosity,
// and k is the wavenumber. The projection step forces the Fourier
// velocity vectors to be orthogonal to the vectors for each
// wavenumber: v(k,t) = v(k,t) - ((k dot v(k,t) * k) / k^2.
__global__ void
diffuseProject_k(cData *vx, cData *vy, int dx, int dy, float dt,
float visc, int lb) {
int gtidx = blockIdx.x * blockDim.x + threadIdx.x;
int gtidy = blockIdx.y * (lb * blockDim.y) + threadIdx.y * lb;
int p;
cData xterm, yterm;
// gtidx is the domain location in x for this thread
if (gtidx < dx) {
for (p = 0; p < lb; p++) {
// fi is the domain location in y for this thread
int fi = gtidy + p;
if (fi < dy) {
int fj = fi * dx + gtidx;
xterm = vx[fj];
yterm = vy[fj];
// Compute the index of the wavenumber based on the
// data order produced by a standard NN FFT.
int iix = gtidx;
int iiy = (fi>dy/2)?(fi-(dy)):fi;
// Velocity diffusion
float kk = (float)(iix * iix + iiy * iiy); // k^2
float diff = 1.f / (1.f + visc * dt * kk);
xterm.x *= diff; xterm.y *= diff;
yterm.x *= diff; yterm.y *= diff;
// Velocity projection
if (kk > 0.f) {
float rkk = 1.f / kk;
// Real portion of velocity projection
float rkp = (iix * xterm.x + iiy * yterm.x);
// Imaginary portion of velocity projection
float ikp = (iix * xterm.y + iiy * yterm.y);
xterm.x -= rkk * rkp * iix;
xterm.y -= rkk * ikp * iix;
yterm.x -= rkk * rkp * iiy;
yterm.y -= rkk * ikp * iiy;
}
vx[fj] = xterm;
vy[fj] = yterm;
}
}
}
}
// This method updates the velocity field 'v' using the two complex
// arrays from the previous step: 'vx' and 'vy'. Here we scale the
// real components by 1/(dx*dy) to account for an unnormalized FFT.
__global__ void
updateVelocity_k(cData *v, float *vx, float *vy,
int dx, int pdx, int dy, int lb, size_t pitch) {
int gtidx = blockIdx.x * blockDim.x + threadIdx.x;
int gtidy = blockIdx.y * (lb * blockDim.y) + threadIdx.y * lb;
int p;
float vxterm, vyterm;
cData nvterm;
// gtidx is the domain location in x for this thread
if (gtidx < dx) {
for (p = 0; p < lb; p++) {
// fi is the domain location in y for this thread
int fi = gtidy + p;
if (fi < dy) {
int fjr = fi * pdx + gtidx;
vxterm = vx[fjr];
vyterm = vy[fjr];
// Normalize the result of the inverse FFT
float scale = 1.f / (dx * dy);
nvterm.x = vxterm * scale;
nvterm.y = vyterm * scale;
cData *fj = (cData*)((char*)v + fi * pitch) + gtidx;
*fj = nvterm;
}
} // If this thread is inside the domain in Y
} // If this thread is inside the domain in X
}
// This method updates the particles by moving particle positions
// according to the velocity field and time step. That is, for each
// particle: p(t+1) = p(t) + dt * v(p(t)).
__global__ void
advectParticles_k(cData *part, cData *v, int dx, int dy,
float dt, int lb, size_t pitch) {
int gtidx = blockIdx.x * blockDim.x + threadIdx.x;
int gtidy = blockIdx.y * (lb * blockDim.y) + threadIdx.y * lb;
int p;
// gtidx is the domain location in x for this thread
cData pterm, vterm;
if (gtidx < dx) {
for (p = 0; p < lb; p++) {
// fi is the domain location in y for this thread
int fi = gtidy + p;
if (fi < dy) {
int fj = fi * dx + gtidx;
pterm = part[fj];
int xvi = ((int)(pterm.x * dx));
int yvi = ((int)(pterm.y * dy));
vterm = *((cData*)((char*)v + yvi * pitch) + xvi);
pterm.x += dt * vterm.x;
pterm.x = pterm.x - (int)pterm.x;
pterm.x += 1.f;
pterm.x = pterm.x - (int)pterm.x;
pterm.y += dt * vterm.y;
pterm.y = pterm.y - (int)pterm.y;
pterm.y += 1.f;
pterm.y = pterm.y - (int)pterm.y;
part[fj] = pterm;
}
} // If this thread is inside the domain in Y
} // If this thread is inside the domain in X
}