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→Assignment 3
=== Assignment 3 ===
=== GPU Optimized Phase 1 ===
<syntaxhighlight lang="cpp">
__global__ void SDFGenerateCuda(const float src[], float dst[], int width, int height, int spread)
{
int size = width * height;
int i = blockIdx.x * blockDim.x + threadIdx.x;
if (i >= size)
return;
float lx = i - ((i / width) * width);
float ly = i / width;
// Used for avoiding unnecessary sqrt calc.
// Just compare the two sqaured distances and
// only use sqrt if it is the shorest distance
float shortestDistSqured = MAX_FLOAT_VALUE;
float pixelVal = src[i];
if (pixelVal > 0) // It's an inside pixel
{
// Find closest outside pixel
for (int j = 0; j < size; j++)
{
float pixelVal2 = src[j];
if (pixelVal2 == 0)// Outside pixel
{
// Calculate distance
float tx = j - ((j / width) * width);
float ty = j / width;
float dx = tx - lx;
float dy = ty - ly;
float distSqured = dx * dx + dy * dy;
if (distSqured < shortestDistSqured) shortestDistSqured = distSqured;
}
}
float shortestDist = sqrtf(shortestDistSqured);
float spread01 = (shortestDist / spread);
if (spread01 > 1) spread01 = 1; // clamp it
dst[i] = (spread01 * .5f) + 0.5f;
}
else // It's an outisde pixel
{
// Find closest inside pixel
for (int j = 0; j < size; j++)
{
float pixelVal2 = src[j];
if (pixelVal2 > 0)// Inside pixel
{
// Calculate distance
float tx = j - ((j / width) * width);
float ty = j / width;
float dx = tx - lx;
float dy = ty - ly;
float distSqured = dx * dx + dy * dy;
if (distSqured < shortestDistSqured) shortestDistSqured = distSqured;
}
}
float shortestDist = sqrtf(shortestDistSqured);
float spread01 = (shortestDist / spread);
if (spread01 > 1) spread01 = 1; // clamp it
dst[i] = (1 - spread01) *.5f;
}
}
</syntaxhighlight lang="cpp">