Alex Selimov
209f483992
- Add missing primitives file - Begin bounding volume hierarchy code - Add some untested base functions for octree and morton encoding - Add interesection tests for box and triangle
51 lines
1.5 KiB
Rust
51 lines
1.5 KiB
Rust
use core::f64;
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use vecmath::{vec3_cross, vec3_dot, vec3_sub};
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use crate::primitives::{Box3, Triangle};
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/// Determine whether two shapes interesect using the separating axis theorem
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pub fn tri_aabb_intersect(bx: &Box3, tri: &Triangle) -> bool {
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// Get edge vectors for triangle
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let e1 = vec3_sub(tri.v2, tri.v1);
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let e2 = vec3_sub(tri.v3, tri.v2);
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let e3 = vec3_sub(tri.v1, tri.v3);
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// Get face and edge normals
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let tri_face = vec3_cross(e1, e2);
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let n1 = vec3_cross(e1, e1);
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let n2 = vec3_cross(e2, e1);
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let n3 = vec3_cross(e3, e1);
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// Face normals AABB
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let u0 = [1.0, 0.0, 0.0];
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let u1 = [0.0, 1.0, 0.0];
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let u2 = [0.0, 0.0, 1.0];
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// Now check all of the axes
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let box_vertices = bx.get_vertices();
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for axis in [u0, u1, u2, tri_face, n1, n2, n3] {
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let box_projection = project_pnts(&box_vertices, axis);
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let tri_projection = project_pnts(&[tri.v1, tri.v2, tri.v3], axis);
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let start = f64::max(box_projection.0, tri_projection.0);
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let end = f64::min(box_projection.1, tri_projection.1);
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if start < end {
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return false;
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}
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}
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return true;
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}
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/// Project points unto an Axis and return the max and min
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fn project_pnts(pnts: &[[f64; 3]], axis: [f64; 3]) -> (f64, f64) {
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let mut min_proj = f64::INFINITY;
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let mut max_proj = f64::NEG_INFINITY;
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for pnt in pnts {
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let projection = vec3_dot(axis, *pnt);
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min_proj = min_proj.min(projection);
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max_proj = max_proj.max(projection);
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}
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(min_proj, max_proj)
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}
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