/* Notes: Keep this is mind when masking the voxel steps, pretty unintuitive behaviour For scalar types, the equality operators return 0 if false and return 1 if true For vector types, the equality operators return 0 if false and return -1 if true (i.e. all bits set) The equality equal (==) returns 0 if one or both arguments are not a number (NaN). The equality not equal (!=) returns 1 (for scalar source operands) or -1 (for vector source operands) if one or both arguments are not a number (NaN). if statements will take 0 as false and any other integer as true */ // ========================================================================= // ======================== INITIALIZER CONSTANTS ========================== __constant float4 zeroed_float4 = {0.0f, 0.0f, 0.0f, 0.0f}; __constant float3 zeroed_float3 = {0.0f, 0.0f, 0.0f}; __constant float2 zeroed_float2 = {0.0f, 0.0f}; __constant int4 zeroed_int4 = {0, 0, 0, 0}; __constant int3 zeroed_int3 = {0, 0, 0}; __constant int2 zeroed_int2 = {0, 0}; // ========================================================================= // ============================ OCTREE CONSTANTS =========================== // (X, Y, Z) mask for the idx __constant const uchar idx_set_x_mask = 0x1; __constant const uchar idx_set_y_mask = 0x2; __constant const uchar idx_set_z_mask = 0x4; __constant const uchar3 idx_set_mask = {0x1, 0x2, 0x4}; __constant const uchar mask_8[8] = { 0x1, 0x2, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80 }; // Mask for counting the previous valid bits __constant const uchar count_mask_8[8] = { 0x1, 0x3, 0x7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF }; // uint64_t manipulation masks __constant const ulong child_pointer_mask = 0x0000000000007fff; __constant const ulong far_bit_mask = 0x8000; __constant const ulong valid_mask = 0xFF0000; __constant const ulong leaf_mask = 0xFF000000; __constant const ulong contour_pointer_mask = 0xFFFFFF00000000; __constant const ulong contour_mask = 0xFF00000000000000; // ========================================================================= // ========================= RAYCASTER CONSTANTS =========================== constant float4 fog_color = { 0.0f, 0.0f, 0.0f, 0.0f }; constant float4 overshoot_color = { 0.00f, 0.00f, 0.00f, 0.00f }; constant float4 overshoot_color_2 = { 0.00f, 0.00f, 0.00f, 0.00f }; // ========================================================================= // ========================================================================= #define setting(name) settings_buffer[name] // ========================================================================= // ========================= HELPER FUNCTIONS ============================== // Phong + diffuse lighting function for g // 0 1 2 3 4 5 6 7 8 9 // {r, g, b, i, x, y, z, x', y', z'} float4 view_light(float4 in_color, float3 light, float4 light_color, float3 view, int3 mask) { if (all(light == zeroed_float3)) return zeroed_float4; float d = fast_length(light) * 0.01f; d *= d; float diffuse = max(dot(normalize(convert_float3(mask)), normalize(light)), 0.1f); float specular = 0.0f; if (diffuse > 0.0f) { // Small dots of light are caused by floating point error // flipping bits on the face mask and screwing up this calculation float3 halfwayVector = normalize(normalize(light) + normalize(view)); float specTmp = max(dot(normalize(convert_float3(mask)), halfwayVector), 0.0f); specular = pow(specTmp, 1.0f); } in_color += diffuse * light_color + specular * light_color / d; return in_color; } int rand(int* seed) // 1 <= *seed < m { int const a = 16807; //ie 7**5 int const m = 2147483647; //ie 2**31-1 *seed = ((*seed) * a) % m; return(*seed); } // ========================================================================= // ========================= OCTREE TRAVERSAL ============================== struct TraversalState { int parent_stack_position; ulong parent_stack[10]; ulong parent_stack_index[10]; uchar scale; uchar idx_stack[10]; ulong current_descriptor; ulong current_descriptor_index; int3 oct_pos; // ====== DEBUG ======= char found; }; struct TraversalState get_oct_vox( int3 position, global ulong *octree_descriptor_buffer, global uint *octree_attachment_lookup_buffer, global ulong *octree_attachment_buffer, global ulong *settings_buffer ){ struct TraversalState ts; // push the root node to the parent stack ts.current_descriptor_index = setting(OCTREE_ROOT_INDEX); ts.current_descriptor = octree_descriptor_buffer[ts.current_descriptor_index]; ts.scale = 0; ts.parent_stack_position = 0; ts.found = false; ts.parent_stack[0] = ts.current_descriptor; // Set our initial dimension and the position at the corner of the oct to keep track of our position int dimension = setting(OCTDIM); ts.oct_pos = zeroed_int3; // While we are not at the required resolution // Traverse down by setting the valid/leaf mask to the subvoxel // Check to see if it is valid // Yes? // Check to see if it is a leaf // No? Break // Yes? Scale down to the next hierarchy, push the parent to the stack // // No? // Break while (dimension > 1) { // So we can be a little bit tricky here and increment our // array index that holds our masks as we build the idx. // Adding 1 for X, 2 for Y, and 4 for Z ts.idx_stack[ts.scale] = 0; // Do the logic steps to find which sub oct we step down into if (position.x >= (dimension / 2) + ts.oct_pos.x) { // Set our voxel position to the (0,0) of the correct oct ts.oct_pos.x += (dimension / 2); // Set the idx to represent the move ts.idx_stack[ts.scale] |= idx_set_x_mask; } if (position.y >= (dimension / 2) + ts.oct_pos.y) { ts.oct_pos.y += (dimension / 2); ts.idx_stack[ts.scale] |= idx_set_y_mask; } if (position.z >= (dimension / 2) + ts.oct_pos.z) { ts.oct_pos.z += (dimension / 2); ts.idx_stack[ts.scale] |= idx_set_z_mask; } int mask_index = ts.idx_stack[ts.scale]; // Check to see if we are on a valid oct if ((ts.current_descriptor >> 16) & mask_8[mask_index]) { // Check to see if it is a leaf if ((ts.current_descriptor >> 24) & mask_8[mask_index]) { // If it is, then we cannot traverse further as CP's won't have been generated ts.found = true; return ts; //return ts.found; } // If all went well and we found a valid non-leaf oct then we will traverse further down the hierarchy ts.scale++; ts.parent_stack_position++; dimension /= 2; // Count the number of valid octs that come before and add it to the index to get the position // Negate it by one as it counts itself int count = popcount((uchar)(ts.current_descriptor >> 16) & count_mask_8[mask_index]) - 1; // access the far point at which the head points too. Determine it's value, and add // a count of the valid bits to the index if (far_bit_mask & octree_descriptor_buffer[ts.current_descriptor_index]) { int far_pointer_index = ts.current_descriptor_index + (ts.current_descriptor & child_pointer_mask); ts.current_descriptor_index = octree_descriptor_buffer[far_pointer_index] + count; } // access the element at which head points to and then add the specified number of indices // to get to the correct child descriptor else { ts.current_descriptor_index = ts.current_descriptor_index + (ts.current_descriptor & child_pointer_mask) + count; } ts.current_descriptor = octree_descriptor_buffer[ts.current_descriptor_index]; ts.parent_stack[ts.parent_stack_position] = ts.current_descriptor; ts.parent_stack_index[ts.parent_stack_position] = ts.current_descriptor_index; } else { // If the oct was not valid, then no CP's exists any further // This implicitly says that if it's non-valid then it must be a leaf!! // It appears that the traversal is now working but I need // to focus on how to now take care of the end condition. // Currently it adds the last parent on the second to lowest // oct CP. Not sure if thats correct ts.found = 0; return ts; //return ts.found; } } ts.found = 1; return ts; //return ts.found; } // ========================================================================= // ========================= RAYCASTER ENTRY =============================== __kernel void raycaster( global char* map, constant int3* map_dim, constant int2* resolution, global float3* projection_matrix, global float2* cam_dir, global float3* cam_pos, global float* lights, global int* light_count, __write_only image2d_t image, __read_only image2d_t texture_atlas, constant int2 *atlas_dim, constant int2 *tile_dim, global ulong *octree_descriptor_buffer, global uint *octree_attachment_lookup_buffer, global ulong *octree_attachment_buffer, global ulong *settings_buffer ){ // Get the pixel on the viewport, and find the view matrix ray that matches it int2 pixel = (int2)(get_global_id(0), get_global_id(1)); float3 ray_dir = projection_matrix[pixel.x + (*resolution).x * pixel.y]; // Pitch ray_dir = (float3)( ray_dir.z * sin((*cam_dir).x) + ray_dir.x * cos((*cam_dir).x), ray_dir.y, ray_dir.z * cos((*cam_dir).x) - ray_dir.x * sin((*cam_dir).x) ); // Yaw ray_dir = (float3)( ray_dir.x * cos((*cam_dir).y) - ray_dir.y * sin((*cam_dir).y), ray_dir.x * sin((*cam_dir).y) + ray_dir.y * cos((*cam_dir).y), ray_dir.z ); if (any(ray_dir == zeroed_float3)) return; // Setup the voxel step based on what direction the ray is pointing // Correct opencl for being stupid and giving us negative for true int3 voxel_step = (-1, -1, -1) * ((ray_dir > 0) - (ray_dir < 0)); // Setup the voxel coords from the camera origin // rtn = round towards negative int3 voxel = convert_int3_rtn(*cam_pos); //voxel = voxel + convert_int3(*cam_pos < 0.0f); // 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); // Intersection T is the collection of the next intersection points // for all 3 axis XYZ. We take the full negative cardinality when // subtracting the floor, so we must transfer the sign over from // the voxel step float3 offset = delta_t * (floor(*cam_pos) - (*cam_pos)); float3 intersection_t = offset * convert_float3(voxel_step); // When we transfer the sign over, we get the correct direction of // the offset, but we merely transposed over the value instead of mirroring // it over the axis like we want. So here, isless returns a boolean if intersection_t // is less than 0 which dictates whether or not we subtract the delta which in effect // mirrors the offset intersection_t -= delta_t * convert_float3(isless(intersection_t, 0)); int distance_traveled = 0; int max_distance = 100; uint bounce_count = 0; int3 face_mask = { 0, 0, 0 }; int voxel_data = 0; float3 face_position = zeroed_float3; float4 voxel_color= zeroed_float4; float2 tile_face_position = zeroed_float2; float3 sign = zeroed_float3; float4 color_accumulator = zeroed_float4; float fog_distance = 0.0f; bool shadow_ray = false; int vox_dim = setting(OCTDIM); struct TraversalState traversal_state; traversal_state = get_oct_vox( voxel, octree_descriptor_buffer, octree_attachment_lookup_buffer, octree_attachment_buffer, settings_buffer); int jump_power = (int)pow((float)2, log2((float)vox_dim) - (float)traversal_state.scale); int prev_jump_power = jump_power; int3 last_oct_pos = (0); // TODO: DEBUG int failsafe = 0; // Andrew Woo's raycasting algo while (distance_traveled < max_distance && bounce_count < 2) { if (jump_power == 2){ color_accumulator = mix((1.0f, 1.0f, 1.0f, 1.0f), (1.0f, 1.0f, 1.0f, 1.0f), 1.0f - max(distance_traveled / 700.0f, 0.0f)); color_accumulator.w *= 4; break; } // If we hit a voxel if (setting(OCTENABLED) == 0 && voxel.x < (*map_dim).x/2 && voxel.y < (*map_dim).x/2 && voxel.z < (*map_dim).x) { traversal_state = get_oct_vox( voxel, octree_descriptor_buffer, octree_attachment_lookup_buffer, octree_attachment_buffer, settings_buffer); // True will result in a -1, e.g (0, 0, -1) so negate it to positive face_mask = -1 * (intersection_t.xyz <= min(intersection_t.yzx, intersection_t.zxy)); prev_jump_power = jump_power; voxel.xyz += voxel_step.xyz * jump_power * face_mask.xyz; // Test for out of bounds contions, add fog if (any(voxel >= *map_dim) || any(voxel < 0)){ voxel.xyz -= voxel_step.xyz * jump_power * face_mask.xyz; color_accumulator = mix(fog_color, voxel_color, 1.0f - max(distance_traveled / 700.0f, 0.0f)); color_accumulator.w *= 4; break; } uchar prev_val = traversal_state.idx_stack[traversal_state.scale]; uchar this_face_mask = 0; // Check the voxel face that we traversed if (face_mask.x) { this_face_mask = idx_set_x_mask; } else if (face_mask.y) { this_face_mask = idx_set_y_mask; } else if (face_mask.z) { this_face_mask = idx_set_z_mask; } // and increment the idx in the idx stack traversal_state.idx_stack[traversal_state.scale] ^= this_face_mask; // Mask index is the 1D index'd value of the idx for interaction with the valid / leaf masks uchar mask_index = traversal_state.idx_stack[traversal_state.scale]; // Whether or not the next oct we want to enter in the current CD's valid mask is 1 or 0 bool is_valid = false; // Check to see if the idx increased or decreased // If it decreased, thus invalid // Pop up the stack until the oct that the idx flip is valid and we landed on a valid oct failsafe = 0; if (mask_index > prev_val) // TODO: Rework this logic so we don't have this bodgy if is_valid = (traversal_state.parent_stack[traversal_state.parent_stack_position] >> 16) & mask_8[mask_index]; while (mask_index < prev_val || !is_valid) { jump_power *= 2; // Keep track of the 0th edge of our current oct traversal_state.oct_pos.x = floor((float)(voxel.x / 2)) * jump_power; traversal_state.oct_pos.y = floor((float)(voxel.y / 2)) * jump_power; traversal_state.oct_pos.z = floor((float)(voxel.z / 2)) * jump_power; // Clear and pop the idx stack traversal_state.idx_stack[traversal_state.scale] = 0; // Scale is now set to the oct above. Be wary of this traversal_state.scale--; // Update the prev_val for our new idx prev_val = traversal_state.idx_stack[traversal_state.scale]; // Clear and pop the parent stack, maybe off by one error? traversal_state.parent_stack_index[traversal_state.parent_stack_position] = 0; traversal_state.parent_stack[traversal_state.parent_stack_position] = 0; traversal_state.parent_stack_position--; // Set the current CD to the one on top of the stack traversal_state.current_descriptor = traversal_state.parent_stack[traversal_state.parent_stack_position]; // Apply the face mask to the new idx for the while check traversal_state.idx_stack[traversal_state.scale] ^= this_face_mask; // Get the mask index of the new idx and check the valid status mask_index = traversal_state.idx_stack[traversal_state.scale]; is_valid = (traversal_state.parent_stack[traversal_state.parent_stack_position] >> 16) & mask_8[mask_index]; failsafe++; if (failsafe > 50) break; } // At this point parent_stack[position] is at the CD of an oct with a // valid oct at the leaf indicated by the current idx in the idx stack scale failsafe = 0; // While we haven't bottomed out and the oct we're looking at is valid while (jump_power > 1 && is_valid) { // If all went well and we found a valid non-leaf oct then we will traverse further down the hierarchy traversal_state.scale++; jump_power /= 2; // Count the number of valid octs that come before and add it to the index to get the position // Negate it by one as it counts itself int count = popcount((uchar)(traversal_state.parent_stack[traversal_state.parent_stack_position] >> 16) & count_mask_8[mask_index]) - 1; //TODO: REWORK THIS IF STATEMENT, PERF KILLER // If this CD had the far bit set if (far_bit_mask & octree_descriptor_buffer[traversal_state.parent_stack_index[traversal_state.parent_stack_position]]) { // access the far point at which the head points too. Determine it's value, and add // the count of the valid bits in the current CD to the index uint far_pointer_index = traversal_state.parent_stack_index[traversal_state.parent_stack_position] + // current index + (traversal_state.parent_stack[traversal_state.parent_stack_position] & child_pointer_mask); // the relative prt to the far ptr // Get the absolute ptr from the far ptr and add the count to get the CD that we want traversal_state.parent_stack_index[traversal_state.parent_stack_position + 1] = octree_descriptor_buffer[far_pointer_index] + count; } // If this CD doesn't have the far bit set, access the element at which head points to // and then add the specified number of indices to get to the correct child descriptor else { traversal_state.parent_stack_index[traversal_state.parent_stack_position + 1] = traversal_state.parent_stack_index[traversal_state.parent_stack_position] + // The current index to this CD (traversal_state.parent_stack[traversal_state.parent_stack_position] & child_pointer_mask) + count; // The relative dist + the number of bits that were valid } // Now that we have the index set we can increase our parent stack position to the next level and // retrieve the value of its CD traversal_state.parent_stack_position++; traversal_state.parent_stack[traversal_state.parent_stack_position] = octree_descriptor_buffer[traversal_state.parent_stack_index[traversal_state.parent_stack_position]]; // Unlike the single shot DFS, it makes a bit more sense to have this at the tail of the while loop // Do the logic steps to find which sub oct we step down into if (voxel.x >= (jump_power / 2) + traversal_state.oct_pos.x) { // Set our voxel position to the (0,0) of the correct oct traversal_state.oct_pos.x += (jump_power / 2); // Set the idx to represent the move traversal_state.idx_stack[traversal_state.scale] |= idx_set_x_mask; } if (voxel.y >= (jump_power / 2) + traversal_state.oct_pos.y) { traversal_state.oct_pos.y += (jump_power / 2); traversal_state.idx_stack[traversal_state.scale] |= idx_set_y_mask; } if (voxel.z >= (jump_power / 2) + traversal_state.oct_pos.z) { traversal_state.oct_pos.z += (jump_power / 2); traversal_state.idx_stack[traversal_state.scale] |= idx_set_z_mask; } // Update the mask index with the new voxel we walked down to, and then check it's valid status mask_index = traversal_state.idx_stack[traversal_state.scale]; is_valid = (traversal_state.parent_stack[traversal_state.parent_stack_position] >> 16) & mask_8[mask_index]; failsafe++; if (failsafe > 50) break; } // Add the delta for the jump power and the traversed face intersection_t += delta_t * jump_power * fabs(convert_float3(face_mask.xyz)); // Get the other faces int3 other_faces = select((int3)(1,1,1), (int3)(0,0,0), (int3)(face_mask == 1)); // Get the amount of times we need to multiply the delta t to get to our face uint3 multiplier = convert_uint3(abs(traversal_state.oct_pos - last_oct_pos) * (1.0f/prev_jump_power)); last_oct_pos = traversal_state.oct_pos; // Go back to the beginning intersection t's for the non traversed faces intersection_t -= delta_t * prev_jump_power * convert_float3(other_faces.xyz); // add back the intersection for our current jump power intersection_t += delta_t * convert_float3(multiplier) * jump_power * fabs(convert_float3(other_faces.xyz)); if (traversal_state.scale == 1 && is_valid){ voxel_data = 5; //voxel.xyz -= voxel_step.xyz * face_mask.xyz; color_accumulator = mix((1.0f, 1.0f, 1.0f, 1.0f), (1.0f, 1.0f, 1.0f, 1.0f), 1.0f - max(distance_traveled / 700.0f, 0.0f)); color_accumulator.w *= 4; break; } //voxel_data = map[voxel.x + (*map_dim).x * (voxel.y + (*map_dim).z * (voxel.z))]; } else { // True will result in a -1, e.g (0, 0, -1) so negate it to positive face_mask = -1 * (intersection_t.xyz <= min(intersection_t.yzx, intersection_t.zxy)); intersection_t += delta_t * convert_float3(face_mask.xyz); voxel.xyz += voxel_step.xyz * face_mask.xyz; // Test for out of bounds contions, add fog if (any(voxel >= *map_dim) || any(voxel < 0)){ voxel.xyz -= voxel_step.xyz * face_mask.xyz; color_accumulator = mix(fog_color, voxel_color, 1.0f - max(distance_traveled / 700.0f, 0.0f)); color_accumulator.w *= 4; break; } voxel_data = map[voxel.x + (*map_dim).x * (voxel.y + (*map_dim).z * (voxel.z))]; } if (voxel_data == 5 || voxel_data == 6) { // Determine where on the 2d plane the ray intersected face_position = zeroed_float3; tile_face_position = zeroed_float2; // Collect the sign of the face hit for ray redirection sign = (1.0f, 1.0f, 1.0f); // First determine the percent of the way the ray is towards the next intersection_t // in relation to the xyz position on the plane if (face_mask.x == 1) { sign.x *= -1.0; // the next intersection for this plane - the last intersection of the passed plane / delta of this plane // basically finds how far in on the other 2 axis we are when the ray traversed the plane float z_percent = (intersection_t.z - (intersection_t.x - delta_t.x)) / delta_t.z; float y_percent = (intersection_t.y - (intersection_t.x - delta_t.x)) / delta_t.y; // Since we intersected face x, we know that we are at the face (1.0) // I think the 1.001f rendering bug is the ray thinking it's within the voxel // even though it's sitting on the very edge face_position = (float3)(1.00001f, y_percent, z_percent); tile_face_position = face_position.yz; } else if (face_mask.y == 1) { sign.y *= -1.0; float x_percent = (intersection_t.x - (intersection_t.y - delta_t.y)) / delta_t.x; float z_percent = (intersection_t.z - (intersection_t.y - delta_t.y)) / delta_t.z; face_position = (float3)(x_percent, 1.00001f, z_percent); tile_face_position = face_position.xz; } else if (face_mask.z == 1) { sign.z *= -1.0; float x_percent = (intersection_t.x - (intersection_t.z - delta_t.z)) / delta_t.x; float y_percent = (intersection_t.y - (intersection_t.z - delta_t.z)) / delta_t.y; face_position = (float3)(x_percent, y_percent, 1.00001f); tile_face_position = face_position.xy; } // Because the raycasting process is agnostic to the quadrant // it's working in, we need to transpose the sign over to the face positions. // If we don't it will think that it is always working in the (1, 1, 1) quadrant // and will just "copy" the quadrant. This includes shadows as they use the face_position // in order to cast the intersection ray!! face_position.x = select((face_position.x), (-face_position.x + 1.0f), (int)(ray_dir.x > 0)); tile_face_position.x = select((tile_face_position.x), (-tile_face_position.x + 1.0f), (int)(ray_dir.x < 0)); if (ray_dir.y > 0){ face_position.y = -face_position.y + 1; } else { tile_face_position.x = 1.0 - tile_face_position.x; // We run into the Hairy ball problem, so we need to define // a special case for the zmask if (face_mask.z == 1) { tile_face_position.x = 1.0f - tile_face_position.x; tile_face_position.y = 1.0f - tile_face_position.y; } } face_position.z = select((face_position.z), (-face_position.z + 1.0f), -1 * (int)(ray_dir.z > 0)); tile_face_position.y = select((tile_face_position.y), (-tile_face_position.y + 1.0f), -1 * (int)(ray_dir.z < 0)); // Now we detect what type of of voxel we intersected and decide whether // to bend the ray, send out a light intersection ray, or add texture color // TEXTURE HIT + SHADOW RAY REDIRECTION if (voxel_data == 5 && !shadow_ray){ shadow_ray = true; voxel_color.xyz += (float3)read_imagef( texture_atlas, convert_int2(tile_face_position * convert_float2(*atlas_dim / *tile_dim)) + convert_int2((float2)(5, 0) * convert_float2(*atlas_dim / *tile_dim)) ).xyz/2; color_accumulator = view_light( voxel_color, (convert_float3(voxel) + face_position) - (float3)(lights[4], lights[5], lights[6]), (float4)(lights[0], lights[1], lights[2], lights[3]), (convert_float3(voxel) + face_position) - (*cam_pos), face_mask * voxel_step ); fog_distance = distance_traveled; max_distance = distance_traveled + fast_distance(convert_float3(voxel), (float3)(lights[4], lights[5], lights[6])); float3 hit_pos = convert_float3(voxel) + face_position; ray_dir = normalize((float3)(lights[4], lights[5], lights[6]) - hit_pos); if (any(ray_dir == zeroed_float3)) return; voxel -= voxel_step * face_mask; voxel_step = ( -1, -1, -1 ) * ((ray_dir > 0) - (ray_dir < 0)); delta_t = fabs(1.0f / ray_dir); intersection_t = delta_t * ((hit_pos) - floor(hit_pos)) * convert_float3(voxel_step); intersection_t += delta_t * -convert_float3(isless(intersection_t, 0)); // REFLECTION } else if (voxel_data == 6 && !shadow_ray) { voxel_color.xyz += (float3)read_imagef( texture_atlas, convert_int2(tile_face_position * convert_float2(*atlas_dim / *tile_dim)) + convert_int2((float2)(3, 4) * convert_float2(*atlas_dim / *tile_dim)) ).xyz/4; voxel_color.w -= 0.0f; float3 hit_pos = convert_float3(voxel) + face_position; ray_dir *= sign; if (any(ray_dir == zeroed_float3)) return; voxel -= voxel_step * face_mask; voxel_step = ( -1, -1, -1 ) * (ray_dir > 0) - (ray_dir < 0); delta_t = fabs(1.0f / ray_dir); intersection_t = delta_t * ((hit_pos)-floor(hit_pos)) * convert_float3(voxel_step); intersection_t += delta_t * -convert_float3(isless(intersection_t, 0)); bounce_count += 1; // SHADOW RAY HIT } else { color_accumulator.w = 0.1f; break; } } // At the bottom of the while loop, add one to the distance ticker distance_traveled++; } color_accumulator = mix(fog_color, color_accumulator, 1.0f - max(fog_distance / 700.0f, 0.0f)); write_imagef( image, pixel, color_accumulator ); return; }