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// global : local : constant : private
// Function arguments of type image2d_t, image3d_t, image2d_array_t, image1d_t, image1d_buffer_t,
// and image1d_array_t refer to image memory objects allocated in the **global** address space.
// http://downloads.ti.com/mctools/esd/docs/opencl/memory/buffers.html
// Open CL C
// https://www.fixstars.com/en/opencl/book/OpenCLProgrammingBook/opencl-c/
__kernel void hello(
global int2* resolution,
global char* map,
global float3* projection_matrix,
global float3* cam_dir,
global float3* cam_pos,
global image2d_t* canvas) {
printf("%s\n", "this is a test string\n");
const int MAX_RAY_STEPS = 64;
// The pixel coord we are at
int2 screenPos = (int2)(get_global_id(0) % resolution->x, get_global_id(0) / resolution->x);
// The X and Y planes
//float3 cameraPlaneU = vec3(1.0, 0.0, 0.0)
// Y being multiplied by the aspect ratio, usually around .5-6ish;
//cl_float3 cameraPlaneV = vec3(0.0, 1.0, 0.0) * iResolution.y / iResolution.x;
// So this is how they do that ray aiming! hah this is so tiny
// (camera direction) + (pixel.x * the X plane) + (product of pixel.y * Y plane)
// Oh all it's doing is adding the x and y coords of the pixel to the camera direction vector, interesting
//cl_float3 rayDir = cameraDir + screenPos.x * cameraPlaneU + screenPos.y * cameraPlaneV;
// the origin of the ray
// So the sign thing is for the up and down motion
//cl_float3 rayPos = vec3(0.0, 2.0 * sin(iGlobalTime * 2.7), -12.0);
// Ah, and here is where it spins around the center axis
// So it looks like its applying a function to rotate the x and z axis
//rayPos.xz = rotate2d(rayPos.xz, iGlobalTime);
//rayDir.xz = rotate2d(rayDir.xz, iGlobalTime);
// Just an intvec of out coords
//ivec3 mapPos = ivec3(floor(rayPos));
// I think this is the delta t value
// the magnitude of the vector divided by the rays direction. Not sure what the aim of that is
// The ray direction might always be normalized, so that would be the dame as my delta_T
//vec3 deltaDist = abs(vec3(length(rayDir)) / rayDir);
// The steps are the signs of the ray direction
//ivec3 rayStep = ivec3(sign(rayDir));
// ithe sign of the rays direction
// *
// Convert map position to a floating point vector and take away the ray position
// +
// the sign of the rays direction by 0.5
// +
// 0.5
// Now multyply everything by 0.5
//vec3 sideDist = (sign(rayDir) * (vec3(mapPos) - rayPos) + (sign(rayDir) * 0.5) + 0.5) * deltaDist;
// A byte mask
//bvec3 mask;
// repeat until the max steps
//for (int i = 0; i < MAX_RAY_STEPS; i++) {
// If there is a voxel at the map position, continue?
//if (getVoxel(mapPos))
// break;
//
// find which is smaller
// y ? z --> x`
// z ? x --> y`
// x ? y --> z`
//
// find which os is less or equal
// x` ? x --> x
// y` ? y --> y
// z` ? z --> z
// Now find which ons is
//mask = lessThanEqual(sideDist.xyz, min(sideDist.yzx, sideDist.zxy));
// Originally he used a component wise
/*bvec3 b1 = lessThan(sideDist.xyz, sideDist.yzx);
bvec3 b2 = lessThanEqual(sideDist.xyz, sideDist.zxy);
mask.x = b1.x && b2.x;
mask.y = b1.y && b2.y;
mask.z = b1.z && b2.z;*/
//Would've done mask = b1 && b2 but the compiler is making me do it component wise.
//All components of mask are false except for the corresponding largest component
//of sideDist, which is the axis along which the ray should be incremented.
//sideDist += vec3(mask) * deltaDist;
//mapPos += ivec3(mask) * rayStep;
//}
// Ah this is for coloring obviously, seems to be odd though, no indexing
//vec4 color;
//if (mask.x) {
// color = vec4(0.5);
//}
//if (mask.y) {
// color = vec4(1.0);
//}
//if (mask.z) {
// color = vec4(0.75);
//}
//write_imagef(image, pixel, color);
}