335 lines
9.5 KiB
WebGPU Shading Language
335 lines
9.5 KiB
WebGPU Shading Language
struct VoxelStructureNode
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{
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pointers: array<u32, 64>
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}
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struct VoxelColorNode
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{
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pointers: array<vec4<f32>, 64>
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}
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struct CacheNodeRequest
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{
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location_info: u32,
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request_count: u32
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}
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struct CacheNodeUsageBuffer
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{
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touch_time: u32,
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parent: u32,
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}
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// Rendering kernels
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struct ChunkInfo
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{
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mvp: mat4x4<f32>,
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eye_pos: vec3<f32>,
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root_color: vec4<f32>,
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root_subdiv: u32,
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frame_timestamp: u32,
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}
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struct StructureNode
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{
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pointers: array<u32, 64>
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}
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struct RequestElement
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{
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pointers: array<atomic<u32>, 64>
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}
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struct ColorNode
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{
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colors: array<vec4<f32>, 64>
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}
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struct VertexOutput
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{
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@builtin(position) postion: vec4<f32>,
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@location(0) world_loc: vec3<f32>,
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@location(1) cam_pos: vec3<f32>,
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}
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var<immediate> constants: ChunkInfo;
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//var<push_constant> constants: ChunkInfo;
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@vertex
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fn chunk(@builtin(vertex_index) index: u32) -> VertexOutput
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{
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let cube_vertices = array<vec3<f32>, 8>(
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vec3<f32>(0., 0., 0.),
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vec3<f32>(0., 0., 1.),
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vec3<f32>(1., 0., 1.),
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vec3<f32>(1., 0., 0.),
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vec3<f32>(0., 1., 0.),
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vec3<f32>(0., 1., 1.),
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vec3<f32>(1., 1., 1.),
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vec3<f32>(1., 1., 0.),
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);
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let cube_faces = array<u32, 24>(
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// Bottom face
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1, 0, 2, 3,
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// Top face
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4, 5, 7, 6,
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// Side faces
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0, 1, 4, 5,
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1, 2, 5, 6,
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2, 3, 6, 7,
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3, 0, 7, 4,
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);
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let quad_index = index / (3 * 2);
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let triangle_index = index % (3 * 2);
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let triangle_map = array<u32, 6>(
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0, 1, 2, 1, 3, 2
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);
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let vertex = cube_vertices[cube_faces[quad_index * 4 + triangle_map[triangle_index]]];
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let output_vertex = constants.mvp * vec4<f32>(vertex, 1.0f);
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var output: VertexOutput;
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output.postion = output_vertex;
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output.world_loc = vertex;
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output.cam_pos = constants.eye_pos;
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//let output = vec4<f32>(vertex, 1.0f);
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return output;
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}
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@group(0) @binding(0) var<storage, read> structure_buffer: array<StructureNode>;
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@group(0) @binding(1) var<storage, read> color_buffer: array<ColorNode>;
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@group(0) @binding(2) var<storage, read_write> request_buffer: array<RequestElement>;
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@group(0) @binding(3) var<storage, read_write> usage_buffer: array<u32>;
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fn box_inter(pos: vec3<f32>, ray_dir: vec3<f32>, box_min: vec3<f32>, box_max: vec3<f32>) -> vec2<f32>
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{
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let box_min_t = (box_min - pos) / ray_dir;
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let box_max_t = (box_max - pos) / ray_dir;
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let near_ts = min(box_min_t, box_max_t);
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let far_ts = max(box_min_t, box_max_t);
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let far_t = min(min(far_ts.x, far_ts.y), far_ts.z);
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let near_t = max(max(near_ts.x, near_ts.y), near_ts.z);
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return vec2(near_t, far_t);
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}
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fn sdf(voxel: vec3<i32>) -> bool
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{
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let len = length(vec3<f32>(voxel) - vec3(128)) / 128.;
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return len <= 1.;
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}
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fn min_vec(x: vec3<f32>) -> f32
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{
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return min(x.x, min(x.y, x.z));
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}
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fn min_mask(x: vec3<f32>) -> vec3<bool>
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{
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let min = min(x.x, min(x.y, x.z));
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return vec3<bool>(min == x.x, min == x.y, min == x.z);
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}
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fn node_subdivided(node: u32) -> bool
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{
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return (node >> 31) != 0;
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}
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fn node_pointer_valid(node: u32) -> bool
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{
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return ((node >> 30) & 1) != 0;
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}
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fn node_pointer(node: u32) -> u32
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{
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return node & 0x3FFFFFFF;
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}
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fn voxel_from_wall(position: vec3<f32>, ray_dir: vec3<f32>) -> vec3<i32>
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{
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let integers = round(position);
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let wall_mask = min_mask(abs(position - vec3<f32>(integers)));
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let offsets = select(vec3<f32>(-0.5), vec3<f32>(0.5), ray_dir > vec3(0.));
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return vec3<i32>(floor(position + select(vec3<f32>(0.), offsets, wall_mask)));
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}
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fn traverse(ray_dir: vec3<f32>, ray_origin: vec3<f32>, root_color: vec4<f32>, root_subdiv: bool) -> vec4<f32>
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{
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// Simple FVT
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let t_off = abs(1. / ray_dir);
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// Start location
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let voxel_dir = select(vec3(-1), vec3(1), ray_dir >= vec3(0.));
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var pos_origin = clamp(ray_origin * 256., vec3(0.), vec3(256. - 1.));
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var voxel = vec3<i32>(pos_origin);
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var last_voxel = voxel;
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let wall_offset = select(vec3(0), vec3(1), ray_dir > vec3(0.));
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var dfs_stack = array<u32, 5>(0, 0, 0, 0, 0);
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// Current depth of the node we are exploring
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var current_depth = 0;
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// Index of the current node's data
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var current_node = u32(0);
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// Current node size
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var node_size = 4 * 4 * 4 * 4; // 128
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// Size of a child of this node
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var child_size = node_size / 4;
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// Lut of the node_size per depth
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var node_size_lut = array<i32, 5>(
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4 * 4 * 4 * 4,
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4 * 4 * 4,
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4 * 4,
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4,
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1,
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);
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let depth_limit = 1;
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for(var iter = 0; iter < 256; iter ++)
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{
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// Our ray is currently touching a voxel.
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// Descend to the lowest node that contains this voxel
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// Position of the child we are in
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var child_pos = (vec3<u32>(voxel) >> vec3<u32>((4 - u32(current_depth + 1)) * 2)) & vec3<u32>(3); // Hardcode for 4-tree
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var child_index = child_pos.x + child_pos.y * 4 + child_pos.z * 4 * 4;
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// Current node has been used. report
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usage_buffer[current_node] = constants.frame_timestamp;
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while(
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node_subdivided(structure_buffer[current_node].pointers[child_index])
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&& current_depth < depth_limit)
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{
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if(!node_pointer_valid(structure_buffer[current_node].pointers[child_index]))
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{
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atomicAdd(&request_buffer[current_node].pointers[child_index], 1);
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break;
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}
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// Child node is subdivided, we go in, save position in stack
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current_node = node_pointer(structure_buffer[current_node].pointers[child_index]);
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usage_buffer[current_node] = constants.frame_timestamp;
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current_depth += 1;
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dfs_stack[current_depth] = current_node;
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node_size = node_size_lut[current_depth];
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child_pos = (vec3<u32>(voxel) >> vec3<u32>((4 - u32(current_depth + 1)) * 2)) & vec3<u32>(3); // Hardcode for 4-tree
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child_index = child_pos.x + child_pos.y * 4 + child_pos.z * 4 * 4;
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child_size = node_size / 4;
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}
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// At this point current_depth is the depth of the node that contains the voxel
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// child_pos and child_index relate to the specific child of the node that contains this voxel
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// It is guaranteed that the child is leave
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// Check current leave's color
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let color = color_buffer[current_node].colors[child_index];
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if(color.w != 0.) // Not transparent
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{
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let k = child_pos.x + child_pos.y + child_pos.z;
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let x = select(0.5, 1., k % 2 == 0);
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return x * color / f32(current_depth);
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}
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// Voxel and whole child containing it is empty
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// Perform a step through the children of the node
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let child_position = (voxel / child_size) * child_size;
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let far_corner = child_position + wall_offset * child_size;
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let far_ts = (vec3<f32>(far_corner) - pos_origin) / ray_dir; // TODO: Turn into fma
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let far_t = min(min(far_ts.x, far_ts.y), far_ts.z);
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let next_child_min = select(child_position, child_position + wall_offset * child_size, vec3(far_t) == far_ts);
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let next_child_max = next_child_min + vec3(child_size);
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// The ray (far_t) is now touching the new child to explore
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// Find out which actual voxel we are touching
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let previous_voxel = voxel;
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let float_voxel = clamp(pos_origin + far_t * ray_dir, vec3<f32>(next_child_min), vec3<f32>(next_child_max));
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/*
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voxel = vec3<i32>(
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floor(
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select(
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float_voxel - vec3(0.5),
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float_voxel + vec3(0.5),
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ray_dir > vec3(0.)
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))
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);
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*/
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//voxel = vec3<i32>(round(float_voxel));
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voxel = voxel_from_wall(float_voxel, ray_dir);
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if(any(voxel < vec3(0)) || any(voxel >= vec3(256)))
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{
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//return vec4(f32(iter) / 100.);
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discard;
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}
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// We touched a voxel as if we explored blocks sized by the child size of the current node.
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// But we might have exited the current node.
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// If this is the case we have to walk back up the tree
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// And then back down to the next node over
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// As such we find the lowest ancestor that can contain both the privous voxel (in node) and the new voxel (out of node)
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let bit_diffs = voxel ^ previous_voxel;
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let bit_diffs_lowest = bit_diffs.x | bit_diffs.y | bit_diffs.z;
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let flb = ((countLeadingZeros(bit_diffs_lowest) - 24) / 2);
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let common_depth = flb;
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current_depth = common_depth;
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node_size = node_size_lut[current_depth];
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child_size = node_size / 4;
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current_node = dfs_stack[current_depth];
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// Figure out current voxel position
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//voxel = vec3<i32>(ray_origin + ray_dir * t);
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}
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return vec4<f32>(1., 0., 1., 1.);
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}
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@fragment
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fn fragment(in: VertexOutput) -> @location(0) vec4<f32>
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{
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let ray_dir = normalize(in.world_loc - in.cam_pos);
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let interp = box_inter(in.cam_pos, ray_dir, vec3(0.), vec3(1));
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let ray_origin = in.cam_pos + ray_dir * (max(0., interp.x));
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return traverse(ray_dir, ray_origin, constants.root_color, constants.root_subdiv != 0);
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return vec4(interp.y / 10.);
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}
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// Cache managment kernels
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// Request buffer managment
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// Compaction
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@workgroup_size(64)
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fn main(
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@builtin(global_invocation_id) gid: vec3<u32>
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)
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{
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let cache_size = 1024;
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let index = gid.x;
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for()
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}
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