1 files changed, 157 insertions, 0 deletions
diff --git a/src/alpha.h b/src/alpha.h
new file mode 100644
index 0000000..afd7ea5
--- /dev/null
+++ b/src/alpha.h
@@ -0,0 +1,157 @@
+#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 5
+
+struct HitList
+{
+	int size;
+	int indices[ALPHA_DEPTH];
+	float distances[ALPHA_DEPTH];
+};
+
+__device__ void add_to_hit_list(const float &distance, const int &index, HitList &h)
+{
+	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__ __noinline__ 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))
+		return 0;
+
+	int stack[STACK_SIZE];
+
+	int *head = &stack[0];
+	int *node = &stack[1];
+	int *tail = &stack[STACK_SIZE-1];
+	*node = g_start_node;
+
+	int i;
+
+	do
+	{
+		int first_child = tex1Dfetch(node_map, *node);
+		int child_count = tex1Dfetch(node_length, *node);
+
+		while (*node >= g_first_node && child_count == 1)
+		{
+			*node = first_child;
+			first_child = tex1Dfetch(node_map, *node);
+			child_count = tex1Dfetch(node_length, *node);
+		}
+		
+		if (*node >= g_first_node)
+		{
+			for (i=0; i < child_count; i++)
+			{
+				if (intersect_node(origin, direction, first_child+i))
+				{
+					*node = first_child+i;
+					node++;
+				}
+			}
+
+			node--;
+		}
+		else // node is a leaf
+		{
+			for (i=0; i < child_count; i++)
+			{
+				uint4 triangle_data = g_triangles[first_child+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, first_child+i, h);
+				}
+
+			} // triangle loop
+
+			node--;
+
+		} // node is a leaf
+
+	} // while loop
+	while (node != head);
+
+	if (h.size < 1)
+		return 0;
+
+	float scale = 1.0;
+	unsigned int r = 0;
+	unsigned int g = 0;
+	unsigned int b = 0;
+	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;
+
+		r += floorf(r0*scale*cos_theta*alpha);
+		g += floorf(g0*scale*cos_theta*alpha);
+		b += floorf(b0*scale*cos_theta*alpha);
+
+		scale *= (1.0f-alpha);
+	}
+
+	return r << 16 | g << 8 | b;
+}
+
+#endif