75 lines
2.7 KiB
Rust
75 lines
2.7 KiB
Rust
//! Module containing the frustum struct.
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//!
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//! The frustum is the field of view of a camera. It allows you to make computation to know what is
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//! visible or not in an efficient manner, though it doesn't take occlusions into account.
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use nalgebra::Matrix4;
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use math::vector::Vector3;
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use math::plane::Plane;
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use math::bounding_box::BoundingBox3;
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/// Struct containing the 6 planes of a 3D camera.
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#[derive(Copy, Clone)]
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pub struct Frustum {
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/// The planes of the frustum.
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planes: [Plane; 6],
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}
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impl Frustum {
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/// Creates a frustum from its four planes.
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pub fn new(planes: [Plane; 6]) -> Frustum {
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Frustum {
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planes: planes,
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}
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}
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/// Creates a frustum for a camera matrix.
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pub fn from_matrix(m: &Matrix4<f32>) -> Frustum {
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// let m0 = m[(0, 0)]; let m1 = m[(0, 1)]; let m2 = m[(0, 2)]; let m3 = m[(0, 3)];
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// let m4 = m[(1, 0)]; let m5 = m[(1, 1)]; let m6 = m[(1, 2)]; let m7 = m[(1, 3)];
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// let m8 = m[(2, 0)]; let m9 = m[(2, 1)]; let m10 = m[(2, 2)]; let m11 = m[(2, 3)];
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// let m12 = m[(3, 0)]; let m13 = m[(3, 1)]; let m14 = m[(3, 2)]; let m15 = m[(3, 3)];
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// Swapped version...
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let m0 = m[(0, 0)]; let m1 = m[(1, 0)]; let m2 = m[(2, 0)]; let m3 = m[(3, 0)];
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let m4 = m[(0, 1)]; let m5 = m[(1, 1)]; let m6 = m[(2, 1)]; let m7 = m[(3, 1)];
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let m8 = m[(0, 2)]; let m9 = m[(1, 2)]; let m10 = m[(2, 2)]; let m11 = m[(3, 2)];
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let m12 = m[(0, 3)]; let m13 = m[(1, 3)]; let m14 = m[(2, 3)]; let m15 = m[(3, 3)];
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Frustum {
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planes: [
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Plane::from_coordinates(m3 - m0, m7 - m4, m11 - m8, m15 - m12),
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Plane::from_coordinates(m3 + m0, m7 + m4, m11 + m8, m15 + m12),
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Plane::from_coordinates(m3 + m1, m7 + m5, m11 + m9, m15 + m13),
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Plane::from_coordinates(m3 - m1, m7 - m5, m11 - m9, m15 - m13),
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Plane::from_coordinates(m3 - m2, m7 - m6, m11 - m10, m15 - m14),
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Plane::from_coordinates(m3 + m2, m7 + m6, m11 + m10, m15 + m14),
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],
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}
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}
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/// Returns true if the intersection of the frustum and the bounding box is not empty.
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pub fn intersects_box(&self, bbox: BoundingBox3<f32>) -> bool {
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use num::Zero;
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let mut p = Vector3::<f32>::zero();
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for plane in &self.planes {
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p[0] = if plane.normal().x() > 0.0 { bbox.max().x() } else { bbox.min().x() };
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p[1] = if plane.normal().y() > 0.0 { bbox.max().y() } else { bbox.min().y() };
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p[2] = if plane.normal().z() > 0.0 { bbox.max().z() } else { bbox.min().z() };
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if plane.distance_to_point(p) < 0.0 {
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return false;
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}
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}
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true
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}
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}
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