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#ifndef __ALPHA_H__
#define __ALPHA_H__
#include "linalg.h"
#include "intersect.h"
#include "mesh.h"
template <class T>
__device__ void swap(T &a, T &b)
{
T temp = a;
a = b;
b = temp;
}
#define ALPHA_DEPTH 10
struct HitList
{
unsigned int size;
unsigned int indices[ALPHA_DEPTH];
float distances[ALPHA_DEPTH];
};
__device__ void add_to_hit_list(const float &distance, const int &index, HitList &h)
{
unsigned int i;
if (h.size >= ALPHA_DEPTH)
{
if (distance > h.distances[ALPHA_DEPTH-1])
return;
i = ALPHA_DEPTH-1;
}
else
{
i = h.size;
h.size += 1;
}
h.indices[i] = index;
h.distances[i] = distance;
while (i > 0 && h.distances[i-1] > h.distances[i])
{
swap(h.distances[i-1], h.distances[i]);
swap(h.indices[i-1], h.indices[i]);
i -= 1;
}
}
__device__ int get_color_alpha(const float3 &origin, const float3& direction)
{
HitList h;
h.size = 0;
float distance;
if (!intersect_node(origin, direction, g_start_node, -1.0f))
return 0;
unsigned int stack[STACK_SIZE];
unsigned int *head = &stack[0];
unsigned int *node = &stack[1];
unsigned int *tail = &stack[STACK_SIZE-1];
*node = g_start_node;
unsigned int i;
do
{
unsigned int first_child = tex1Dfetch(node_map, *node);
unsigned int stop = tex1Dfetch(node_map_end, *node);
while (*node >= g_first_node && stop == first_child+1)
{
*node = first_child;
first_child = tex1Dfetch(node_map, *node);
stop = tex1Dfetch(node_map_end, *node);
}
if (*node >= g_first_node)
{
for (i=first_child; i < stop; i++)
{
if (intersect_node(origin, direction, i, -1.0f))
{
*node = i;
node++;
}
}
node--;
}
else // node is a leaf
{
for (i=first_child; i < stop; i++)
{
uint4 triangle_data = g_triangles[i];
float3 v0 = g_vertices[triangle_data.x];
float3 v1 = g_vertices[triangle_data.y];
float3 v2 = g_vertices[triangle_data.z];
if (intersect_triangle(origin, direction, v0, v1, v2, distance))
{
add_to_hit_list(distance, i, h);
}
} // triangle loop
node--;
} // node is a leaf
} // while loop
while (node != head);
if (h.size < 1)
return 0;
float scale = 1.0f;
float fr = 0.0f;
float fg = 0.0f;
float fb = 0.0f;
for (i=0; i < h.size; i++)
{
uint4 triangle_data = g_triangles[h.indices[i]];
float3 v0 = g_vertices[triangle_data.x];
float3 v1 = g_vertices[triangle_data.y];
float3 v2 = g_vertices[triangle_data.z];
float cos_theta = dot(normalize(cross(v1-v0,v2-v1)),-direction);
if (cos_theta < 0.0f)
cos_theta = dot(-normalize(cross(v1-v0,v2-v1)),-direction);
unsigned int r0 = 0xff & (g_colors[h.indices[i]] >> 16);
unsigned int g0 = 0xff & (g_colors[h.indices[i]] >> 8);
unsigned int b0 = 0xff & g_colors[h.indices[i]];
float alpha = (255 - (0xff & (g_colors[h.indices[i]] >> 24)))/255.0f;
fr += r0*scale*cos_theta*alpha;
fg += g0*scale*cos_theta*alpha;
fb += b0*scale*cos_theta*alpha;
scale *= (1.0f-alpha);
}
unsigned int r = floorf(fr);
unsigned int g = floorf(fg);
unsigned int b = floorf(fb);
return r << 16 | g << 8 | b;
}
#endif
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