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voxel-rs
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Rewrite raycast shader to take larger steps when encountering empty chunks

This commit is contained in:
Jarrod Doyle 2023-04-29 14:48:24 +01:00
parent 63e1fd94bd
commit b857b5a157
Signed by: Jayrude
GPG Key ID: 38B57B16E7C0ADF7
1 changed files with 111 additions and 26 deletions
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137
assets/shaders/voxel_volume.wgsl
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@ -58,10 +58,15 @@ fn get_shading_offset(p: vec3<i32>) -> u32 {
return (*brickmap).shading_table_offset + map_voxel_idx; return (*brickmap).shading_table_offset + map_voxel_idx;
} }
fn ray_intersect_aabb(ray_pos: vec3<f32>, ray_dir: vec3<f32>) -> AabbHitInfo { fn ray_intersect_aabb(
ray_pos: vec3<f32>,
ray_dir: vec3<f32>,
min: vec3<f32>,
max: vec3<f32>
) -> AabbHitInfo {
let ray_dir_inv = 1.0 / ray_dir; let ray_dir_inv = 1.0 / ray_dir;
let t1 = -ray_pos * ray_dir_inv; let t1 = (min - ray_pos) * ray_dir_inv;
let t2 = (vec3<f32>(8u * world_state.brickmap_cache_dims) - ray_pos) * ray_dir_inv; let t2 = (max - ray_pos) * ray_dir_inv;
let t_min = min(t1, t2); let t_min = min(t1, t2);
let t_max = max(t1, t2); let t_max = max(t1, t2);
let tmin = max(max(t_min.x, 0.0), max(t_min.y, t_min.z)); let tmin = max(max(t_min.x, 0.0), max(t_min.y, t_min.z));
@ -69,34 +74,37 @@ fn ray_intersect_aabb(ray_pos: vec3<f32>, ray_dir: vec3<f32>) -> AabbHitInfo {
return AabbHitInfo(tmax > tmin, tmin); return AabbHitInfo(tmax > tmin, tmin);
} }
fn point_inside_aabb(p: vec3<i32>) -> bool { fn point_inside_aabb(p: vec3<i32>, min: vec3<i32>, max: vec3<i32>) -> bool {
let max = vec3<i32>(world_state.brickmap_cache_dims) * 8; let clamped = clamp(p, min, max - vec3<i32>(1));
let clamped = clamp(p, vec3<i32>(0), max - vec3<i32>(1));
return clamped.x == p.x && clamped.y == p.y && clamped.z == p.z; return clamped.x == p.x && clamped.y == p.y && clamped.z == p.z;
} }
fn voxel_hit(p: vec3<i32>) -> bool { fn voxel_hit(brickmap_idx: u32, p: vec3<i32>) -> bool {
let brickgrid_index = to_1d_index(p / 8, vec3<i32>(world_state.brickmap_cache_dims));
let brick_ptr = brickgrid[brickgrid_index];
if ((brick_ptr & 1u) == 0u){
return false;
}
let local_index = to_1d_index(p % 8, vec3<i32>(8)); let local_index = to_1d_index(p % 8, vec3<i32>(8));
let bitmask_segment = brickmap_cache[brick_ptr >> 8u].bitmask[local_index / 32u]; let bitmask_segment = brickmap_cache[brickmap_idx].bitmask[local_index / 32u];
return (bitmask_segment >> (local_index % 32u) & 1u) != 0u; return (bitmask_segment >> (local_index % 32u) & 1u) != 0u;
} }
fn cast_ray(orig_ray_pos: vec3<f32>, ray_dir: vec3<f32>) -> HitInfo { fn brick_ray_cast(
chunk_pos: vec3<i32>,
brickmap_idx: u32,
orig_ray_pos: vec3<f32>,
ray_dir: vec3<f32>
) -> HitInfo {
var hit_info = HitInfo(false, vec3<i32>(0), vec3<bool>(false)); var hit_info = HitInfo(false, vec3<i32>(0), vec3<bool>(false));
let aabbHit = ray_intersect_aabb(orig_ray_pos, ray_dir);
var ray_pos = orig_ray_pos; var ray_pos = orig_ray_pos * 8.0;
let min = vec3<f32>(chunk_pos * 8);
let max = min + vec3<f32>(8.0);
let aabbHit = ray_intersect_aabb(ray_pos, ray_dir, min, max);
var tmin = aabbHit.distance; var tmin = aabbHit.distance;
if (aabbHit.hit) { if (aabbHit.hit) {
// Accelerate ray // Accelerate ray
if (tmin > 0.0) { if (tmin > 0.0) {
ray_pos += ray_dir * (tmin - 0.0001); ray_pos += ray_dir * (tmin + 0.0001);
} }
tmin = max(0.0, tmin); tmin = max(0.0, tmin);
@ -105,9 +113,20 @@ fn cast_ray(orig_ray_pos: vec3<f32>, ray_dir: vec3<f32>) -> HitInfo {
let ray_step = vec3<i32>(sign(ray_dir)); let ray_step = vec3<i32>(sign(ray_dir));
var map_pos = vec3<i32>(floor(ray_pos)); var map_pos = vec3<i32>(floor(ray_pos));
var side_dist = (sign(ray_dir) * (vec3<f32>(map_pos) - ray_pos) + (sign(ray_dir) * 0.5) + 0.5) * delta_dist; var side_dist = (sign(ray_dir) * (vec3<f32>(map_pos) - ray_pos) + (sign(ray_dir) * 0.5) + 0.5) * delta_dist;
map_pos = map_pos % 8;
let max_brick_depth = 8 * 8 * 8;
for (var i: i32 = 0; i < max_brick_depth; i++) {
if (!point_inside_aabb(map_pos, vec3<i32>(0), vec3<i32>(8))) {
break;
}
if (voxel_hit(brickmap_idx, map_pos)){
hit_info.hit = true;
hit_info.hit_pos = map_pos;
break;
}
// TODO: don't hardcode max ray depth
for (var i: i32 = 0; i < 2048; i++) {
if (side_dist.x < side_dist.y) { if (side_dist.x < side_dist.y) {
if (side_dist.x < side_dist.z) { if (side_dist.x < side_dist.z) {
side_dist.x += delta_dist.x; side_dist.x += delta_dist.x;
@ -132,15 +151,81 @@ fn cast_ray(orig_ray_pos: vec3<f32>, ray_dir: vec3<f32>) -> HitInfo {
hit_info.mask = vec3<bool>(false, false, true); hit_info.mask = vec3<bool>(false, false, true);
} }
} }
}
}
if (!point_inside_aabb(map_pos)) { return hit_info;
}
fn grid_cast_ray(orig_ray_pos: vec3<f32>, ray_dir: vec3<f32>) -> HitInfo {
var hit_info = HitInfo(false, vec3<i32>(0), vec3<bool>(false));
let min = vec3<f32>(0.0);
let max = min + vec3<f32>(world_state.brickmap_cache_dims);
let aabbHit = ray_intersect_aabb(orig_ray_pos, ray_dir, min, max);
var ray_pos = orig_ray_pos;
var tmin = aabbHit.distance;
if (aabbHit.hit) {
// Accelerate ray
if (tmin > 0.0) {
ray_pos += ray_dir * (tmin + 0.0001);
}
tmin = max(0.0, tmin);
// Convert ray_pos into chunk scale
// ray_pos /= 8.0;
// DDA setup
let delta_dist = abs(length(ray_dir) / ray_dir);
let ray_step = vec3<i32>(sign(ray_dir));
var map_pos = vec3<i32>(floor(ray_pos));
var side_dist = (sign(ray_dir) * (vec3<f32>(map_pos) - ray_pos) + (sign(ray_dir) * 0.5) + 0.5) * delta_dist;
let max_grid_depth = i32(length(vec3<f32>(world_state.brickmap_cache_dims)));
for (var i: i32 = 0; i < max_grid_depth; i++) {
if (!point_inside_aabb(map_pos, vec3<i32>(0), vec3<i32>(world_state.brickmap_cache_dims))) {
break; break;
} }
if (voxel_hit(map_pos)) { let grid_idx = to_1d_index(map_pos, vec3<i32>(world_state.brickmap_cache_dims));
hit_info.hit = true; let brick_ptr = brickgrid[grid_idx];
hit_info.hit_pos = map_pos;
break; // If brick pointers loaded flag is set
if ((brick_ptr & 1u) == 1u) {
let brickmap_idx = brick_ptr >> 8u;
let tmp_voxel_hit = brick_ray_cast(map_pos, brickmap_idx, orig_ray_pos, ray_dir);
if (tmp_voxel_hit.hit == true){
hit_info.hit = tmp_voxel_hit.hit;
hit_info.hit_pos = tmp_voxel_hit.hit_pos + (map_pos * 8);
hit_info.mask = tmp_voxel_hit.mask;
break;
}
}
if (side_dist.x < side_dist.y) {
if (side_dist.x < side_dist.z) {
side_dist.x += delta_dist.x;
map_pos.x += ray_step.x;
hit_info.mask = vec3<bool>(true, false, false);
}
else {
side_dist.z += delta_dist.z;
map_pos.z += ray_step.z;
hit_info.mask = vec3<bool>(false, false, true);
}
}
else {
if (side_dist.y < side_dist.z) {
side_dist.y += delta_dist.y;
map_pos.y += ray_step.y;
hit_info.mask = vec3<bool>(false, true, false);
}
else {
side_dist.z += delta_dist.z;
map_pos.z += ray_step.z;
hit_info.mask = vec3<bool>(false, false, true);
}
} }
} }
} }
@ -167,7 +252,7 @@ fn compute(@builtin(global_invocation_id) global_id: vec3<u32>) {
let ray_pos = camera.pos; let ray_pos = camera.pos;
// Cast the ray // Cast the ray
var hit_info = cast_ray(ray_pos, ray_dir); var hit_info = grid_cast_ray(ray_pos, ray_dir);
var color = vec4<f32>(0.0, 0.0, 0.0, 1.0); var color = vec4<f32>(0.0, 0.0, 0.0, 1.0);
if (hit_info.hit){ if (hit_info.hit){
// if (hit_info.mask.x) { // if (hit_info.mask.x) {