Triangle functionality

src/points.rs

@@ -7,6 +7,7 @@ pub struct Point2D {
     pub x: f64,
     pub y: f64
 }
+
 #[derive(Debug, Clone, Copy)]
 pub struct Point3D {
     pub x: f64, pub y: f64, pub z: f64
@@ -118,4 +119,10 @@ impl Point2D {
                 + f64::powf(p2.y.max(p1.y) - p1.y.min(p2.y), 2.0)) as f64,
         )
     }
+
+    pub fn gradient(self, p2: &Point2D) -> f64 {
+        let p1 = self;
+        
+        (p2.y - p1.y) / (p2.x - p1.x)
+    }
 }

src/render.rs

@@ -1,5 +1,5 @@
 use crate::consts::*;
-use crate::points::Point2D;
+use crate::points::{Point2D, Point3D};
 use crate::Scene;
 
 type Pixel = u32;
@@ -62,8 +62,29 @@ pub fn render(scene: &Scene, buf: &mut [u32]) {
             }
         }
 
-        for faces in &obj.faces {
 
+        for (p0, p1, p2) in &obj.faces {
+
+            let (p0, p1, p2) = (p0.to_screen_coordinates(), p1.to_screen_coordinates(), p2.to_screen_coordinates());
+            // Finds the leftmost and rightmost points on the triangle and only iterates over them.
+            let horizontal_range = p0.x.min(p1.x.min(p2.x)) as usize..=p0.x.max(p1.x.max(p2.x)) as usize;
+            let vertical_range = p0.y.min(p1.y.min(p2.y)) as usize..=p0.y.max(p1.y.max(p2.y)) as usize;
+
+            for x in horizontal_range.clone() {
+                for y in vertical_range.clone() {
+                    let p = Point2D{x: x as f64, y: y as f64};
+
+                    let area = 0.5 *(-p1.y*p2.x + p0.y*(-p1.x + p2.x) + p0.x*(p1.y - p2.y) + p1.x*p2.y);
+                    let s = 1.0/(2.0*area)*(p0.y*p2.x - p0.x*p2.y + (p2.y - p0.y)*p.x + (p0.x - p2.x)*p.y);
+                    let t = 1.0/(2.0*area)*(p0.x*p1.y - p0.y*p1.x + (p0.y - p1.y)*p.x + (p1.x - p0.x)*p.y);
+
+                    if s > 0.0 && t > 0.0 && 1.0 - s - t > 0.0 {
+                        // dbg!(p);
+                        *index_buffer(buf, p) = to_rgb((255, 255, 255));
+                    };
+                }
+            }
+            
         }
 
     }

src/scene.rs

@@ -6,7 +6,7 @@ use crate::points::Scene;
 pub fn set_scene(dt: Duration, scene: &mut Scene) {
     for obj in scene {
         for vertex in obj.vertices.iter_mut() {
-            vertex.z += 1.0;
+            // vertex.z += 1.0;
         }
 
         obj.update();