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Merge pull request #8 from saaaji/wrtg3030_proj
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Wrtg3030 proj
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@saaaji
saaaji authored Nov 7, 2024
2 parents 447ae94 + e2b158e commit a1e2ec8
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Showing 21 changed files with 1,999 additions and 22 deletions.
Binary file added WRTG3030_MockAcademicArticle_RayTracingAcceleration.pdf
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271 changes: 271 additions & 0 deletions mock_aa_impl/assets/shaders/bvh_util.wgsl
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const BVH_STACK_SIZE: i32 = 32;

fn ray_bvh_isect_fixed_enc_df(
ray: Ray,
t_min: f32,
t_max: f32,
info: ptr<function, IsectInfo>
) -> bool {
var any_hit: bool = false;
var t_closest: f32 = t_max;
var temp_info: IsectInfo;
(*info).cost = 0;

var<function> stack: array<i32, BVH_STACK_SIZE>;
var ptr: i32 = 0;
stack[ptr] = 0;
ptr++;

while (ptr > 0) {
ptr--;
let idx = stack[ptr];
let node = bvh[idx];

var dummy_t: f32;
if (ray_aabb_isect(ray, node.mini, node.maxi, t_min, t_closest, &dummy_t)) {
(*info).cost += 0.5;

if (node.prim_or_split < 0) {
if (ptr < BVH_STACK_SIZE - 2) {
let split_axis = abs(node.prim_or_split) - 1;

var first = idx + 1;
var second = node.child_or_miss;

if (ray.d[split_axis] < 0) {
let temp = first;
first = second;
second = temp;
}

stack[ptr] = second;
ptr++;
stack[ptr] = first;
ptr++;
} else {
break;
}
} else {
let tri: TriPrim = fetch_tri(node.prim_or_split);

let old_cost = (*info).cost;
if (ray_tri_isect(ray, tri, t_min, t_closest, &temp_info)) {
any_hit = true;
t_closest = temp_info.t;
(*info) = temp_info;
}

(*info).cost = old_cost + 1.0;
}
}
}

return any_hit;
}

fn ray_bvh_isect_stackless_enc_df(
ray: Ray,
t_min: f32,
t_max: f32,
info: ptr<function, IsectInfo>
) -> bool {
var any_hit: bool = false;
var t_closest: f32 = t_max;
var temp_info: IsectInfo;
(*info).cost = 0;

var idx: i32 = 0;

while (idx >= 0) {
let node = bvh[idx];

var dummy_t: f32;
if (ray_aabb_isect(ray, node.mini, node.maxi, t_min, t_closest, &dummy_t)) {
(*info).cost += 0.5;

if (node.prim_or_split < 0) {
// follow depth first order
idx += 1;
} else {
let tri: TriPrim = fetch_tri(node.prim_or_split);

let old_cost = (*info).cost;
if (ray_tri_isect(ray, tri, t_min, t_closest, &temp_info)) {
any_hit = true;
t_closest = temp_info.t;
(*info) = temp_info;
}

// for leaf node, DF & miss-link order are identical
idx = node.child_or_miss;
(*info).cost = old_cost + 1.0;
}
} else {
// follow miss index
idx = node.child_or_miss;
}
}

return any_hit;
}

// DEPRECATED IMPLEMENTATION
/*
fn ray_bvh_isect_ordered_enc_bf(
ray: Ray,
t_min: f32,
t_max: f32,
info: ptr<function, IsectInfo>,
) -> bool {
var any_hit: bool = false;
var t_closest: f32 = t_max;
var temp_info: IsectInfo;
(*info).cost = 0;

*overflow = vec3f(1, 0, 0);

var<function> stack: array<i32, BVH_STACK_SIZE>;
var ptr: i32 = 0;
stack[ptr] = 0;
ptr++;

while (ptr > 0) {
ptr--;
let idx = stack[ptr];
let node = bvh[idx];

var dummy_t: f32;
if (ray_aabb_isect(ray, node.mini, node.maxi, t_min, t_closest, &dummy_t)) {
(*info).cost += 0.5;

let old_cost = (*info).cost;
if (node.prim_or_split < 0) {
if (ptr < BVH_STACK_SIZE - 2) {
let split_axis = abs(node.prim_or_split) - 1;
let d_sign01 = vec3i(ray.d > vec3f(0));
let order = d_sign01[split_axis];

stack[ptr] = node.child_or_miss + order;
ptr++;
stack[ptr] = node.child_or_miss + 1 - order;
ptr++;
} else {
break;
}
} else {
let tri: TriPrim = fetch_tri(node.prim_or_split);

let old_cost = (*info).cost;
if (ray_tri_isect(ray, tri, t_min, t_closest, &temp_info)) {
any_hit = true;
t_closest = temp_info.t;
(*info) = temp_info;
}

(*info).cost = old_cost + 1.0;
}
}
}

return any_hit;
}
*/

fn ray_bvh_isect_ordered_enc_bf(
ray: Ray,
t_min: f32,
t_max: f32,
info: ptr<function, IsectInfo>,
) -> bool {
var any_hit: bool = false;
var t_closest: f32 = t_max;
var temp_info: IsectInfo;
(*info).cost = 0;

// special case where root is a leaf
let root = bvh[0];
if (root.prim_or_split >= 0) {
var dummy_t: f32;

(*info).cost += 1.5; // 0.5 for AABB test, 1.0 for triangle test

return ray_aabb_isect(ray, root.mini, root.maxi, t_min, t_closest, &dummy_t) &&
ray_tri_isect(ray, fetch_tri(root.prim_or_split), t_min, t_closest, info);
}

// initialize the stack
var<function> stack: array<i32, BVH_STACK_SIZE>;
var ptr: i32 = 0;

var first_child_idx = root.child_or_miss;
loop {
var left = bvh[first_child_idx];
var right = bvh[first_child_idx + 1];
var left_t: f32;
var right_t: f32;

// intersect both children at same time
var left_hit_node = ray_aabb_isect(ray, left.mini, left.maxi, t_min, t_closest, &left_t);
var right_hit_node = ray_aabb_isect(ray, right.mini, right.maxi, t_min, t_closest, &right_t);
(*info).cost += 1.0; // 2x 0.5 for AABB tests

if (left_hit_node) {
if (left.prim_or_split >= 0) {
let old_cost = (*info).cost;
if (ray_tri_isect(ray, fetch_tri(left.prim_or_split), t_min, t_closest, &temp_info)) {
any_hit = true;
t_closest = temp_info.t;
(*info) = temp_info;
}
(*info).cost = old_cost + 1.0;
left_hit_node = false;
}
}

if (right_hit_node) {
if (right.prim_or_split >= 0) {
let old_cost = (*info).cost;
if (ray_tri_isect(ray, fetch_tri(right.prim_or_split), t_min, t_closest, &temp_info)) {
any_hit = true;
t_closest = temp_info.t;
(*info) = temp_info;
}
(*info).cost = old_cost + 1.0;
right_hit_node = false;
}
}

// determine traversal order
if (left_hit_node) {
if (right_hit_node) {
// sort based on intersection distances
if (left_t > right_t) {
let temp = left;
left = right;
right = temp;
}

if (ptr <= BVH_STACK_SIZE - 1) {
stack[ptr] = right.child_or_miss;
ptr++;
} else {
break;
}
}
first_child_idx = left.child_or_miss;
} else if (right_hit_node) {
// only the right node was intersected
first_child_idx = right.child_or_miss;
} else {
// no intersections were found, check the stack
if (ptr <= 0) {
break;
}

ptr--;
first_child_idx = stack[ptr];
}
}

return any_hit;
}
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