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//-*-c-*-
__device__ __host__ Matrix inv(const Matrix&m, float& determinant)
{
determinant = det(m);
return make_matrix(m.a11*m.a22 - m.a12*m.a21,
m.a02*m.a21 - m.a01*m.a22,
m.a01*m.a12 - m.a02*m.a11,
m.a12*m.a20 - m.a10*m.a22,
m.a00*m.a22 - m.a02*m.a20,
m.a02*m.a10 - m.a00*m.a12,
m.a10*m.a21 - m.a11*m.a20,
m.a01*m.a20 - m.a00*m.a21,
m.a00*m.a11 - m.a01*m.a10)/determinant;
}
__device__ bool intersect_triangle(const float3 &x, const float3 &p, float3 *vertex, float3 &intersection)
{
float determinant;
float3 u = inv(make_matrix(vertex[1]-vertex[0],vertex[2]-vertex[0],-p), determinant)*(x-vertex[0]);
if (determinant == 0.0)
return false;
if (u.x < 0.0 || u.y < 0.0 || u.z < 0.0 || (1-u.x-u.y) < 0.0)
return false;
intersection = x + p*u.z;
return true;
}
__device__ int get_color(const float3 &p, float3 *vertex)
{
float3 v1 = vertex[1] - vertex[0];
float3 v2 = vertex[2] - vertex[0];
float3 normal = cross(v1,v2);
float scale;
scale = dot(normal,-p)/(norm(normal)*norm(p));
if (scale < 0.0)
scale = dot(-normal,-p)/(norm(normal)*norm(p));
int rgb = floorf(255*scale);
return rgb*65536 + rgb*256 + rgb;
}
extern "C"
{
__global__ void translate(int max_idx, float3 *x, float3 v)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
x[idx] += v;
}
__global__ void rotate(int max_idx, float3 *x, float phi, float3 axis)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
x[idx] = rotate(x[idx], phi, axis);
}
__global__ void intersect_triangle_mesh(int max_idx, float3 *x, float3 *p, int n, float3 *mesh, int *pixel)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
bool hit = false;
float distance, min_distance;
float3 intersection, min_intersection;
int i;
for (i=0; i < n; i++)
{
if (intersect_triangle(x[idx], p[idx], mesh+3*i, intersection))
{
if (!hit)
{
pixel[idx] = get_color(p[idx], mesh+3*i);
min_distance = norm(intersection-x[idx]);
min_intersection = intersection;
hit = true;
continue;
}
distance = norm(intersection-x[idx]);
if (distance < min_distance)
{
pixel[idx] = get_color(p[idx], mesh+3*i);
min_distance = distance;
min_intersection = intersection;
}
}
}
if (!hit)
pixel[idx] = 0;
}
} // extern "c"
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