voxel-raycaster/kernels/minimal_kernel.cl

__kernel void min_kern(
        global char* map,
        global int3* map_dim,
        global int2* resolution,
        global float3* projection_matrix,
        global float3* cam_dir,
        global float3* cam_pos,
        __write_only image2d_t image
){

    size_t id = get_global_id(0);

    int2 pixel = {id % resolution->x, id / resolution->x};

    float3 ray_dir = projection_matrix[pixel.x + resolution->x * pixel.y];
    //printf("%i === %f, %f, %f\n", id, ray_dir.x, ray_dir.y, ray_dir.z);

    // Y axis, pitch
    //ray_dir.x = ray_dir.z * sin(cam_dir->y) + ray_dir.x * cos(cam_dir->y);
    //ray_dir.y = ray_dir.y;
    //ray_dir.z = ray_dir.z * cos(cam_dir->y) - ray_dir.x * sin(cam_dir->y);


    ray_dir = (float3)(
            ray_dir.z * sin(cam_dir->y) + ray_dir.x * cos(cam_dir->y),
            ray_dir.y,
            ray_dir.z * cos(cam_dir->y) - ray_dir.x * sin(cam_dir->y)
    );

    // Z axis, yaw
    //ray_dir.x = ray_dir.x * cos(cam_dir->z) - ray_dir.y * sin(cam_dir->z);
    //ray_dir.y = ray_dir.x * sin(cam_dir->z) + ray_dir.y * cos(cam_dir->z);
    //ray_dir.z = ray_dir.z;

    ray_dir = (float3)(
            ray_dir.x * cos(cam_dir->z) - ray_dir.y * sin(cam_dir->z),
            ray_dir.x * sin(cam_dir->z) + ray_dir.y * cos(cam_dir->z),
            ray_dir.z
    );


    // Setup the voxel step based on what direction the ray is pointing
    int3 voxel_step = {1, 1, 1};
    voxel_step.x *= (ray_dir.x > 0) - (ray_dir.x < 0);
    voxel_step.y *= (ray_dir.y > 0) - (ray_dir.y < 0);
    voxel_step.z *= (ray_dir.z > 0) - (ray_dir.z < 0);

    // Setup the voxel coords from the camera origin
    int3 voxel = {
            floor(cam_pos->x),
            floor(cam_pos->y),
            floor(cam_pos->z)
    };

    // Delta T is the units a ray must travel along an axis in order to
    // traverse an integer split
    float3 delta_t = {
            fabs(1.0f / ray_dir.x),
            fabs(1.0f / ray_dir.y),
            fabs(1.0f / ray_dir.z)
    };

    // Intersection T is the collection of the next intersection points
    // for all 3 axis XYZ.
    float3 intersection_t = {
            delta_t.x,
            delta_t.y,
            delta_t.z
    };


    int dist = 0;
    int face = -1;
    // X:0, Y:1, Z:2


	int3 mask = { 0, 0, 0 };

    // Andrew Woo's raycasting algo
    do {

		mask = intersection_t.xyz <= min(intersection_t.yzx, intersection_t.zxy);
		float3 thing = delta_t * fabs(convert_float3(mask.xyz));
		intersection_t += delta_t * fabs(convert_float3(mask.xyz));
		voxel.xyz += voxel_step.xyz * mask.xyz;



        // If the ray went out of bounds
		int3 overshoot = voxel.xyz <= map_dim->xyz;
		int3 undershoot = voxel > 0;

		//if (id == 240000)
		//	printf("%i, %i, %i\n", overshoot.x, overshoot.y, overshoot.z);

		//if (id == 240000)
		//	printf("%i, %i, %i\n", undershoot.x, undershoot.y, undershoot.z);
		
		if (overshoot.x == 0|| overshoot.y == 0 || overshoot.z == 0){
			write_imagef(image, pixel, (float4)(.50 * abs(overshoot.x), .50 * abs(overshoot.y), .50 * abs(overshoot.z), 1));
			return;
		}
		if (undershoot.x == 0 || undershoot.y == 0 || undershoot.z == 0) {
			write_imagef(image, pixel, (float4)(.1 * abs(undershoot.x), .80 * abs(undershoot.y), .20 * abs(undershoot.z), 1));
			return;
		}
        //if (voxel.x >= map_dim->x) {
        //    write_imagef(image, pixel, (float4)(.00, .00, .99, 1));
        //    return;
        //}
        //if (voxel.y >= map_dim->x) {
        //    write_imagef(image, pixel, (float4)(.00, .44, .00, 1));
        //    return;
        //}

        //if (voxel.x < 0) {
        //    write_imagef(image, pixel, (float4)(.99, .00, .99, 1));
        //    return;
        //}
        //if (voxel.y < 0) {
        //    write_imagef(image, pixel, (float4)(.99, .99, .00, 1));
        //    return;
        //}
        //if (voxel.z < 0) {
        //    write_imagef(image, pixel, (float4)(.00, .99, .99, 1));
        //    return;
        //}

        // If we hit a voxel
        int index = voxel.x + map_dim->x * (voxel.y + map_dim->z * voxel.z);
        int voxel_data = map[index];



		if (voxel_data != 0) {
			switch (voxel_data) {
			case 1:
				write_imagef(image, pixel, (float4)(.50, .00, .00, 1));
				return;
			case 2:
				write_imagef(image, pixel, (float4)(.00, .50, .40, 1.00));
				//if (id == 249000)
				   // printf("%i\n", voxel_data);
				return;
			case 3:
				write_imagef(image, pixel, (float4)(.00, .00, .50, 1.00));
				return;
			case 4:
				write_imagef(image, pixel, (float4)(.25, .00, .25, 1.00));
				return;
			case 5:
				write_imagef(image, pixel, (float4)(.10, .30, .80, 1.00));
				return;
			case 6:
				write_imagef(image, pixel, (float4)(.30, .80, .10, 1.00));
				return;
			}
		}

        dist++;
    } while (dist < 2500);


    write_imagef(image, pixel, (float4)(.00, .00, .00, .00));
    return;

    //printf("%i %i -- ", id, map[id]);
    //printf("%i, %i, %i\n", map_dim->x, map_dim->y, map_dim->z);
    //printf("\n%i\nX: %f\nY: %f\nZ: %f\n", id, projection_matrix[id].x, projection_matrix[id].y, projection_matrix[id].z);
    //printf("%f, %f, %f\n", cam_dir->x, cam_dir->y, cam_dir->z);
    //printf("%f, %f, %f\n", cam_pos->x, cam_pos->y, cam_pos->z);

}