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2026-09-15 13:39:56 +02:00

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struct PushConstants
{
float4x4 view_proj;
float3 cam_pos;
uint32_t frame_timestamp;
uint32_t width;
uint32_t height;
uint32_t chunk_width;
uint32_t chunk_height;
uint32_t chunk_alt;
}
public struct VertexOutput
{
public float4 position : SV_Position;
[vk::location(0)]
public float3 world_position;
[vk::location(1)]
public nointerpolation uint32_t structure_id;
[vk::location(2)]
public float3 cam_position;
[vk::location(3)]
public float3 chunk_position;
}
[[vk::push_constant]]
uniform PushConstants constants;
[shader("vertex")]
VertexOutput chunk(
uint index: SV_VulkanVertexID,
[vk::location(0)] float3 chunk_position,
[vk::location(1)] uint id)
{
let cube_vertices : float3[8] =
float3[](
float3(0., 0., 0.),
float3(0., 0., 1.),
float3(1., 0., 1.),
float3(1., 0., 0.),
float3(0., 1., 0.),
float3(0., 1., 1.),
float3(1., 1., 1.),
float3(1., 1., 0.), );
// clang-format off
let cube_faces: int[24] = int[](
// Bottom face
1, 0, 2, 3,
// Top face
4, 5, 7, 6,
// Side faces
0, 1, 4, 5,
1, 2, 5, 6,
2, 3, 6, 7,
3, 0, 7, 4,
);
let quad_index = index / (3 * 2);
let triangle_index = index % (3 * 2);
let triangle_map: int[6] = int[](
0, 1, 2, 1, 3, 2
);
let vertex = cube_vertices[cube_faces[quad_index * 4 + triangle_map[triangle_index]]];
let output_vertex = mul(constants.view_proj, float4(vertex + chunk_position, 1.0f));
VertexOutput vertex_output;
vertex_output.position = output_vertex;
vertex_output.world_position = vertex + chunk_position;
vertex_output.structure_id = id;
vertex_output.cam_position = constants.cam_pos;
vertex_output.chunk_position = chunk_position;
return vertex_output;
}
struct StructurePointer
{
uint32_t value;
bool subdivided()
{
return (this.value & 0x80000000) != 0;
}
bool pointer_valid()
{
return (this.value & 0x40000000) != 0;
}
bool subdivided_valid()
{
return (this.value & 0xC0000000) == 0xC0000000;
}
uint32_t pointer()
{
return this.value & 0x3FFFFFFF;
}
}
struct ByteColor
{
uint32_t byte_color;
property uint32_t byte_r {
get {return byte_color & 0xFF;}
}
property uint32_t byte_g {
get {return (byte_color >> 8) & 0xFF;}
}
property uint32_t byte_b {
get {return (byte_color >> 16) & 0xFF;}
}
property uint32_t byte_a {
get {return byte_color >> 24;}
}
property float4 float_color {
get {return float4(
float(byte_r) / 255.,
float(byte_g) / 255.,
float(byte_b) / 255.,
float(byte_a) / 255.
); }
}
}
struct StructurePoolElement
{
uint32_t occupancy_low;
uint32_t occupancy_high;
StructurePointer pointers[64];
}
struct RequestBufferElement
{
Atomic<uint32_t> requests[64];
}
struct ColorPoolElement
{
ByteColor colors[64];
}
struct LocationPoolElement
{
uint32_t structure_id;
uint32_t structure_locator;
}
[[vk::binding(0, 0)]] RWStructuredBuffer<StructurePoolElement> structure_pool;
[[vk::binding(1, 0)]] RWStructuredBuffer<ColorPoolElement> color_pool;
[[vk::binding(2, 0)]] RWStructuredBuffer<LocationPoolElement> location_pool;
[[vk::binding(3, 0)]] RWStructuredBuffer<RequestBufferElement> request_buffer;
[[vk::binding(4, 0)]] RWStructuredBuffer<uint32_t> usage_buffer;
[[vk::binding(5, 0)]] RWStructuredBuffer<StructurePointer> structure_table_pointer;
[[vk::binding(6, 0)]] RWStructuredBuffer<Atomic<uint32_t>> structure_table_request_buffer;
uint32_t3 get_children_pos(float3 position, uint32_t scale_exp)
{
return (asuint(position) >> scale_exp) & 3;
}
uint32_t get_children_index(float3 position, uint32_t scale_exp)
{
// Get mantissa bits for this scale exp an retain bits for the specific children
uint32_t3 cell_position = (asuint(position) >> scale_exp) & 3;
return cell_position.x + cell_position.y * 4 + cell_position.z * 4 * 4;
}
uint64_t get_child_mask(uint32_t low, uint32_t high)
{
return ((uint64_t)high << 32) | (uint64_t)low;
}
float3 floor_scale(float3 position, uint32_t scale_exp)
{
uint32_t mask = ~0u << scale_exp;
return asfloat(asuint(position) & mask);
}
struct HitInformation
{
bool hit;
float3 hit_pos;
float4 color;
}
// struct NodeStack
// {
// uint32_t node_stack[5];
// }
groupshared uint32_t stack[256 * 5];
HitInformation ray_march(float3 ray_direction, float3 ray_origin, uint32_t root_id, float dist_offset, uint32_t stack_index)
{
float fov_deg = 100. / 1920.;
float fov_rad = (float.getPi() * fov_deg) / 180.;
float cone_factor = tan(fov_rad / 2.) * 2; // Horizontal size of pixel
let st_pointer = structure_table_pointer[root_id];
if(!st_pointer.subdivided())
{
var hit: HitInformation;
hit.hit = false;
return hit;
}
if(!st_pointer.pointer_valid())
{
// Record request
structure_table_request_buffer[root_id].add(1);
var hit: HitInformation;
hit.hit = false;
return hit;
}
ray_origin += float3(1.);
ray_origin = clamp(ray_origin , float(1.), asfloat(0x3fffffff));
ray_origin = select(ray_direction > 0., asfloat(asuint(ray_origin) ^ 0x007fffff), ray_origin);
uint32_t child_mirror = 0;
if(ray_direction.x > 0.) {child_mirror |= 3;}
if(ray_direction.y > 0.) {child_mirror |= 3 << 2;}
if(ray_direction.z > 0.) {child_mirror |= 3 << 4;}
ray_direction = -abs(ray_direction);
float3 pos = ray_origin;
uint32_t scale_exp = 23 - 2;
uint32_t node_stack[5] =
{
0
};
uint32_t current_node_index = structure_table_pointer[root_id].pointer();
usage_buffer[current_node_index] = constants.frame_timestamp;
stack[stack_index * 5 + 10 - scale_exp / 2] = current_node_index;
//node_stack[10 - scale_exp / 2] = current_node_index;
[loop]
for(uint32_t iter = 0; iter < 500; iter ++)
{
uint32_t child_index = get_children_index(pos, scale_exp) ^ child_mirror;
StructurePointer current_node = structure_pool[current_node_index].pointers[child_index];
// Scale computations
let cone_size = (length(ray_origin - pos) + dist_offset) * cone_factor;
let exponent =
select(
cone_size == 0.,
0,
23 - (127 - (asuint(cone_size) >> 23))
);
while(
current_node.subdivided_valid() &&
scale_exp - 2 > exponent
)
{
scale_exp -= 2;
current_node_index = current_node.pointer();
stack[stack_index * 5 + 10 - scale_exp / 2] = current_node_index;
//node_stack[10 - scale_exp / 2] = current_node_index;
child_index = get_children_index(pos, scale_exp) ^ child_mirror;
current_node = structure_pool[current_node_index].pointers[child_index];
// Write usage
usage_buffer[current_node_index] = constants.frame_timestamp;
}
// Request subdiv
if(current_node.subdivided() && !current_node.pointer_valid())
{
request_buffer[current_node_index].requests[child_index].add(1);
}
if(color_pool[current_node_index].colors[child_index].byte_a != 0)
{
var hit: HitInformation;
hit.hit = true;
hit.hit_pos = pos - float3(1.);
hit.color = color_pool[current_node_index].colors[child_index].float_color;
return hit;
}
uint64_t occupancy = get_child_mask(structure_pool[current_node_index].occupancy_low, structure_pool[current_node_index].occupancy_high);
uint32_t adv_scale_exp = scale_exp;
if(((occupancy >> (child_index & 0b101010)) & 0x00330033) == 0)
{
adv_scale_exp ++;
}
// Perform dda
// Compute correct exponent, and shift it into the exponent part of floatt
let child_pos : float3 = floor_scale(pos, adv_scale_exp);
// Intersection t
let inter_ts : float3 = (child_pos - ray_origin) / ray_direction;
float inter_t = min(inter_ts.x, min(inter_ts.y, inter_ts.z));
//return float4(inter_t);
// Perform dda step
//let neighbor_max = asint(child_pos) + select(inter_t == inter_ts, -1, (1 << adv_scale_exp) - 1);
let neighbor_max = asint(child_pos) + select(inter_t == inter_ts, -1, (1 << adv_scale_exp) - 1);
pos = min(ray_origin + ray_direction * inter_t, asfloat(neighbor_max));
// Find most common ancestor
uint32_t3 diffs = asuint(child_pos) ^ asuint(pos);
uint32_t diff = (diffs.x | diffs.y | diffs.z);
int32_t common_depth = (1 + (22 - firstbithigh(diff)) / 2) * 2;
if(common_depth <= 0)
{
break;
}
scale_exp = 23 - common_depth;
current_node_index = stack[stack_index * 5 + 10 - scale_exp / 2];
//current_node_index = node_stack[10 - scale_exp / 2];
}
var hit: HitInformation;
hit.hit = false;
return hit;
}
struct FragmentOutput
{
float depth : SV_Depth;
float4 color : SV_Target<0>;
}
/*
//[earlydepthstencil]
[shader("fragment")]
FragmentOutput fragment(VertexOutput vertex_out)
{
let ray_direction = normalize(vertex_out.world_position - vertex_out.cam_position);
let intersection_t = box_intersect(vertex_out.cam_position, ray_direction, vertex_out.chunk_position, vertex_out.chunk_position + float3(1.));
let local_ray_origin = max(intersection_t.x, 0.) * ray_direction + vertex_out.cam_position - vertex_out.chunk_position;
// Figure out intersection
let hit = ray_march(ray_direction, local_ray_origin, vertex_out.structure_id, max(0., intersection_t.x));
let world_hit_pos = hit.hit_pos + vertex_out.chunk_position;
let clip = mul(constants.view_proj, float4(world_hit_pos, 1.));
let depth = clip.z / clip.w;
var frag_out : FragmentOutput;
frag_out.depth = depth;
frag_out.color = hit.color;
return frag_out;
}
*/
bool3 min_mask(float3 val)
{
let min_val = min(val.x, min(val.y, val.z));
return val == min_val;
}
[[vk::binding(0, 1)]]
[[format("rgba32f")]]
WTexture2D<float4> output_texture;
float3 get_ray_direction(uint32_t2 pixel_loc)
{
let ndc_loc_x = (float)pixel_loc.x / (float)constants.width * 2. - 1.;
let ndc_loc_y = 1. - (float)pixel_loc.y / (float)constants.height * 2.;
var world_loc = mul(constants.view_proj, float4(ndc_loc_x, ndc_loc_y, 1., 1.));
world_loc /= world_loc.w;
return normalize(world_loc.xyz - constants.cam_pos);
}
[shader("compute")]
[numthreads(16, 16, 1)]
void ray_march_compute(uint32_t3 location : SV_DispatchThreadID, uint32_t3 local_location: SV_GroupThreadID)
{
if(location.x >= constants.width || location.y >= constants.height)
{
return;
}
let stack_index = local_location.x + local_location.y * 16;
let ray_direction = get_ray_direction(location.xy);
var inter = box_intersect(constants.cam_pos, ray_direction, float3(0.), float3(constants.chunk_width, constants.chunk_alt, constants.chunk_height));
// Clear if out of box
if(inter.y <= inter.x || inter.y <= 0.)
{
output_texture.Store(location.xy, float4(0.));
return;
}
inter.x = max(0., inter.x);
// float3 position = constants.cam_pos + ray_direction * inter.x;
// int32_t3 current_voxel = clamp(
// int32_t3(floor(position)),
// int32_t3(0),
// int32_t3(constants.chunk_width - 1, constants.chunk_alt - 1, constants.chunk_height - 1)
// );
// let chunk_index = current_voxel.y + current_voxel.z * constants.chunk_alt + current_voxel.x * constants.chunk_alt * constants.chunk_height;
// let hit = ray_march(ray_direction, position - float3(current_voxel), chunk_index, length(position - constants.cam_pos), stack_index);
// if(hit.hit)
// {
// output_texture.Store(location.xy, float4(hit.color));
// }
let start_position = inter.x * ray_direction + constants.cam_pos;
// FVT
int32_t3 current_voxel = clamp(
int32_t3(floor(start_position)),
int32_t3(0),
int32_t3(constants.chunk_width - 1, constants.chunk_alt - 1, constants.chunk_height - 1)
);
//int32_t3 offset = int32_t3(sign(ray_direction));
//float3 delta = abs(1. / ray_direction);
float3 t = select(ray_direction > 0., current_voxel + int32_t3(1) - start_position, start_position - current_voxel) / abs(ray_direction);
t += inter.x;
[loop]
while(true)
{
{
let off = t - abs(1. / ray_direction);
let t_adv = max(max(off.x, max(off.y, off.z)), 0.);
let chunk_index = current_voxel.y + current_voxel.z * constants.chunk_alt + current_voxel.x * constants.chunk_alt * constants.chunk_height;
let position = constants.cam_pos + ray_direction * t_adv;
let hit = ray_march(ray_direction, position - float3(current_voxel), chunk_index, t_adv, stack_index);
if(hit.hit)
{
output_texture.Store(location.xy, hit.color);
return;
}
}
let min_mask = min_mask(t);
t += select(min_mask, abs(1. / ray_direction), float3(0.));
current_voxel += select(min_mask, int32_t3(sign(ray_direction)), int32_t3(0));
if(any(current_voxel < 0) || any(current_voxel >= int32_t3(constants.chunk_width, constants.chunk_alt, constants.chunk_height)))
{
output_texture.Store(location.xy, float4(0.));
return;
}
}
}
float2 box_intersect(float3 origin, float3 ray_direction, float3 box_min, float3 box_max)
{
let min_ts = (box_min - origin) / ray_direction;
let max_ts = (box_max - origin) / ray_direction;
let far_ts = max(min_ts, max_ts);
let near_ts = min(min_ts, max_ts);
let far_t = min(far_ts.x, min(far_ts.y, far_ts.z));
let near_t = max(near_ts.x, max(near_ts.y, near_ts.z));
return float2(near_t, far_t);
}