Implement CreateFrustumFromCamera

include/J3ML/Geometry.h

@@ -3,12 +3,13 @@
 #pragma once
 
 namespace Geometry {
-    using Point2D = LinearAlgebra::Vector2;
+    using Vector2 = LinearAlgebra::Vector2;
+    using Vector3 = LinearAlgebra::Vector3;
 
     class LineSegment2D
     {
-        Point2D A;
-        Point2D B;
+        Vector2 A;
+        Vector2 B;
     };
 
     class Rectangle; //AABB2D;
@@ -29,7 +30,7 @@ namespace Geometry {
 
     
 
-    using Point3D = LinearAlgebra::Vector3;
+
 
     // A 3D axis-aligned bounding box
     // This data structure can be used to represent coarse bounds of objects, in situations where detailed triangle-level
@@ -44,18 +45,59 @@ namespace Geometry {
     class Line;
     class LineSegment
     {
-        Point3D A;
-        Point3D B;
+        Vector3 A;
+        Vector3 B;
     };
     class Ray
     {
-        Point3D Origin;
-        Point3D Direction;
+        Vector3 Origin;
+        Vector3 Direction;
     };
 
     class OBB;
-    class Frustum;
-    class Plane;
+    class Plane
+    {
+    public:
+        Vector3 Position;
+        Vector3 Normal;
+        float distance = 0.f;
+
+    };
+    class Frustum {
+    public:
+        Plane TopFace;
+        Plane BottomFace;
+        Plane RightFace;
+        Plane LeftFace;
+        Plane FarFace;
+        Plane NearFace;
+    };
+
+    class Camera {
+    public:
+        Vector3 Position;
+        Vector3 Front;
+        Vector3 Right;
+        Vector3 Up;
+    };
+
+    static Frustum CreateFrustumFromCamera(const Camera& cam, float aspect, float fovY, float zNear, float zFar)
+    {
+        Frustum frustum;
+        const float halfVSide = zFar * tanf(fovY * 0.5f);
+        const float halfHSide = halfVSide * aspect;
+
+        const Vector3 frontMultFar = cam.Front * zFar;
+
+        frustum.NearFace  = Plane{cam.Position + cam.Front * zNear, cam.Front};
+        frustum.FarFace   = Plane{cam.Position + frontMultFar, -cam.Front};
+        frustum.RightFace = Plane{cam.Position, Vector3::Cross(frontMultFar - cam.Right * halfHSide, cam.Up)};
+        frustum.LeftFace  = Plane{cam.Position, Vector3::Cross(cam.Up, frontMultFar+cam.Right*halfHSide)};
+        frustum.TopFace   = Plane{cam.Position, Vector3::Cross(cam.Right, frontMultFar - cam.Up * halfVSide)};
+        frustum.BottomFace   = Plane{cam.Position, Vector3::Cross(frontMultFar + cam.Up * halfVSide, cam.Right)};
+        return frustum;
+    }
+
     class Polygon;
     class Polyhedron;
     class QuadTree;