tie fighter

1 files changed, 118 insertions, 0 deletions

diff --git a/src/intersect.cu b/src/intersect.cu
new file mode 100644
index 0000000..844f6fd
--- /dev/null
+++ b/src/intersect.cu
@@ -0,0 +1,118 @@
+//-*-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"