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//-*-c-*-
#include <math_constants.h>
#include "linalg.h"
#include "matrix.h"
#include "rotate.h"
#include "intersect.h"
#define STACK_SIZE 100
/* flattened triangle mesh */
texture<float4, 1, cudaReadModeElementType> mesh;
/* lower/upper bounds for the bounding box associated with each node/leaf */
texture<float4, 1, cudaReadModeElementType> upper_bounds;
texture<float4, 1, cudaReadModeElementType> lower_bounds;
/* map to child nodes/triangles and the number of child nodes/triangles */
texture<uint, 1, cudaReadModeElementType> child_map_arr;
texture<uint, 1, cudaReadModeElementType> child_len_arr;
__device__ float3 make_float3(const float4 &a)
{
return make_float3(a.x, a.y, a.z);
}
/* Test the intersection between a ray starting at `origin` traveling in the
direction `direction` and the bounding box around node `i`. If the ray
intersects the bounding box return true, else return false. */
__device__ bool intersect_node(const float3 &origin, const float3 &direction, const int &i)
{
float3 lower_bound = make_float3(tex1Dfetch(lower_bounds, i));
float3 upper_bound = make_float3(tex1Dfetch(upper_bounds, i));
return intersect_box(origin, direction, lower_bound, upper_bound);
}
/* Find the intersection between a ray starting at `origin` traveling in the
direction `direction` and the global mesh texture. If the ray intersects
the texture return the index of the triangle which the ray intersected,
else return -1. */
__device__ int intersect_mesh(const float3 &origin, const float3& direction, const int first_leaf)
{
int triangle_idx = -1;
float distance;
float min_distance;
if (!intersect_node(origin, direction, 0))
return -1;
int stack[STACK_SIZE];
int *head = &stack[0];
int *node = &stack[1];
int *tail = &stack[STACK_SIZE-1];
*node = 0;
int i;
do
{
int child_map = tex1Dfetch(child_map_arr, *node);
int child_len = tex1Dfetch(child_len_arr, *node);
if (*node < first_leaf)
{
for (i=0; i < child_len; i++)
if (intersect_node(origin, direction, child_map+i))
*node++ = child_map+i;
if (node == head)
break;
node--;
}
else // node is a leaf
{
for (i=0; i < child_len; i++)
{
int mesh_idx = 3*(child_map + i);
float3 v0 = make_float3(tex1Dfetch(mesh, mesh_idx));
float3 v1 = make_float3(tex1Dfetch(mesh, mesh_idx+1));
float3 v2 = make_float3(tex1Dfetch(mesh, mesh_idx+2));
if (intersect_triangle(origin, direction, v0, v1, v2, distance))
{
if (triangle_idx == -1)
{
triangle_idx = child_map + i;
min_distance = distance;
continue;
}
if (distance < min_distance)
{
triangle_idx = child_map + i;
min_distance = distance;
}
}
} // triangle loop
node--;
} // node is a leaf
} // while loop
while (node != head);
return triangle_idx;
}
extern "C"
{
/* Translate `points` by the vector `v` */
__global__ void translate(int max_idx, float3 *points, float3 v)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
*(points+idx) += v;
}
/* Rotate `points` through an angle `phi` counter-clockwise about the
axis `axis` (when looking towards +infinity). */
__global__ void rotate(int max_idx, float3 *points, float phi, float3 axis)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
*(points+idx) = rotate(*(points+idx), phi, axis);
}
/* Trace the rays starting at `origins` traveling in the direction `directions`
to their intersection with the global mesh. If the ray intersects the mesh
set the pixel associated with the ray to a 32 bit color whose brightness is
determined by the cosine of the angle between the ray and the normal of the
triangle it intersected, else set the pixel to 0. */
__global__ void ray_trace(int max_idx, float3 *origins, float3 *directions, int first_leaf, int *pixels)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
float3 origin = *(origins+idx);
float3 direction = *(directions+idx);
direction /= norm(direction);
int intersection_idx = intersect_mesh(origin, direction, first_leaf);
if (intersection_idx == -1)
{
*(pixels+idx) = 0;
}
else
{
int mesh_idx = 3*intersection_idx;
float3 v0 = make_float3(tex1Dfetch(mesh, mesh_idx));
float3 v1 = make_float3(tex1Dfetch(mesh, mesh_idx+1));
float3 v2 = make_float3(tex1Dfetch(mesh, mesh_idx+2));
*(pixels+idx) = get_color(direction, v0, v1, v2);
}
} // ray_trace
/* Propagate the photons starting at `origins` traveling in the direction
`directions` to their intersection with the global mesh. If the ray
intersects the mesh set the hit_solid array value associated with the
photon to the triangle index of the triangle the photon intersected, else
set the hit_solid array value to -1. */
__global__ void propagate(int max_idx, float3 *origins, float3 *directions, int first_leaf, int *hit_solids)
{
int idx = blockIdx.x*blockDim.x + threadIdx.x;
if (idx > max_idx)
return;
float3 origin = *(origins+idx);
float3 direction = *(directions+idx);
direction /= norm(direction);
*(hit_solids+idx) = intersect_mesh(origin, direction, first_leaf);
} // propagate
} // extern "c"
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