Basic brush plane intersection calculation

Cargo.lock

@@ -5,7 +5,19 @@ version = 3
 [[package]]
 name = "csg"
 version = "0.1.0"
+dependencies = [
+ "glam",
+]
 
 [[package]]
 name = "editor"
 version = "0.1.0"
+dependencies = [
+ "csg",
+]
+
+[[package]]
+name = "glam"
+version = "0.24.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42218cb640844e3872cc3c153dc975229e080a6c4733b34709ef445610550226"

csg/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+glam = "0.24.1"

csg/src/brush.rs

@@ -0,0 +1,63 @@
+use glam::Vec3;
+
+use crate::plane::{Plane, PlaneIntersection};
+
+pub struct MaterialId(pub String);
+
+pub struct TextureProjection {
+    pub u: Plane,
+    pub v: Plane,
+}
+
+impl Default for TextureProjection {
+    fn default() -> Self {
+        Self {
+            u: Plane {
+                normal: glam::vec3(1.0, 0.0, 0.0),
+                offset: 0.0,
+            },
+            v: Plane {
+                normal: glam::vec3(0.0, 1.0, 0.0),
+                offset: 0.0,
+            },
+        }
+    }
+}
+
+pub struct BrushPlane {
+    pub plane: Plane,
+    pub material: MaterialId,
+    pub tex_projection: TextureProjection,
+}
+
+pub struct Brush {
+    pub planes: Vec<BrushPlane>,
+}
+
+impl Brush {
+    pub fn get_vertices(&self) -> Vec<Vec3> {
+        if self.planes.len() < 3 {
+            println!("fug");
+            return vec![];
+        }
+
+        let mut vs = vec![];
+        let len = self.planes.len();
+        for i in 0..(len - 2) {
+            for j in (i + 1)..(len - 1) {
+                for k in (j + 1)..len {
+                    if let Some(intersection) = PlaneIntersection::from_planes(
+                        self.planes[i].plane,
+                        self.planes[j].plane,
+                        self.planes[k].plane,
+                    ) {
+                        // TODO: Validate that the found intersection is within all brush planes
+                        vs.push(intersection.get_intersection_point())
+                    }
+                }
+            }
+        }
+
+        vs
+    }
+}

csg/src/lib.rs

@@ -1,3 +1,9 @@
+pub mod brush;
+pub mod math;
+pub mod plane;
+
+pub use glam;
+
 pub fn add(left: usize, right: usize) -> usize {
     left + right
 }

csg/src/math.rs

@@ -0,0 +1 @@
+pub const EPSILON: f32 = 0.0001;

csg/src/plane.rs

@@ -0,0 +1,66 @@
+use glam::{Mat3, Vec3};
+
+use crate::math;
+
+#[derive(Clone, Copy, Debug)]
+pub struct Plane {
+    pub normal: Vec3,
+    pub offset: f32,
+}
+
+impl Plane {
+    pub fn from_point_normal(point: Vec3, normal: Vec3) -> Self {
+        Self {
+            normal,
+            offset: -point.dot(normal),
+        }
+    }
+}
+
+pub struct PlaneIntersection {
+    pub planes: [Plane; 3],
+}
+
+impl PlaneIntersection {
+    pub fn from_planes(p1: Plane, p2: Plane, p3: Plane) -> Option<Self> {
+        let plane = Self {
+            planes: [p1, p2, p3],
+        };
+
+        let determinant = plane.get_matrix().determinant();
+        // println!("Determinant: {determinant}");
+        if determinant.abs() > math::EPSILON {
+            Some(plane)
+        } else {
+            None
+        }
+    }
+
+    pub fn get_intersection_point(&self) -> Vec3 {
+        let base_matrix = self.get_matrix();
+        let base_det = base_matrix.determinant();
+        let offsets = glam::vec3(
+            self.planes[0].offset,
+            self.planes[1].offset,
+            self.planes[2].offset,
+        );
+
+        let mut vs = vec![];
+        for idx in 0..3 {
+            let mut matrix = base_matrix;
+            *(matrix.col_mut(idx)) = -offsets;
+            vs.push(matrix.determinant() / base_det);
+        }
+
+        Vec3::from_slice(&vs)
+    }
+
+    fn get_matrix(&self) -> Mat3 {
+        glam::mat3(
+            self.planes[0].normal,
+            self.planes[1].normal,
+            self.planes[2].normal,
+        )
+        .transpose()
+    }
+}

editor/Cargo.toml

@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+csg = { path = "../csg" }

editor/src/main.rs

@@ -1,3 +1,34 @@
+use csg::{
+    brush::{self, Brush, BrushPlane, MaterialId, TextureProjection},
+    glam::{self},
+    plane::Plane,
+};
+
 fn main() {
-    println!("Hello, world!");
+    let points = vec![
+        glam::vec3(1.0, 0.0, 0.0),
+        glam::vec3(-1.0, 0.0, 0.0),
+        glam::vec3(0.0, 1.0, 0.0),
+        glam::vec3(0.0, -1.0, 0.0),
+        glam::vec3(0.0, 0.0, 1.0),
+        glam::vec3(0.0, 0.0, -1.0),
+    ];
+
+    let mut brush_planes = vec![];
+    for point in &points {
+        brush_planes.push(BrushPlane {
+            plane: Plane::from_point_normal(*point, *point),
+            material: MaterialId("Epic".to_string()),
+            tex_projection: TextureProjection::default(),
+        });
+
+        println!("Plane: {:?}", brush_planes.last().unwrap().plane);
+    }
+
+    let brush = Brush {
+        planes: brush_planes,
+    };
+    let vs = brush.get_vertices();
+
+    println!("Vertices: {vs:?}");
 }