Line Against AABB

The code for Line V AABB is almost the same as the code for Line V Sphere. Both functions are wrappers around a ray cast.

This test will test intersection, it will not test containment. That is, if you have a line, and both start and end points are INSIDE the sphere, the result of this test will be false!

Implementation

Provide an implementation for the following function

    public static bool LineTest(Line line, AABB aabb, out Point result)

Unit Test

You can Download the samples for this chapter to see if your result looks like the unit test.

This unit test will print out errors if any are present in your code.

using OpenTK.Graphics.OpenGL;
using Math_Implementation;
using CollisionDetectionSelector.Primitives;

namespace CollisionDetectionSelector.Samples {
    class LinecastAABB : Application {
        public Line[] lines = new Line[] {
            new Line(new Point(2.5f, 2.5f, 2.5f), new Point(4, 4, 4)), // false
            new Line(new Point(1f, 1f, 0f), new Point(0f, 0f, 0f)), // false
            new Line(new Point(-1f, -1f, 0f), new Point(-3f, 0f, 0f)), // true
            new Line(new Point(-5f, 0f, 0f), new Point(5f, 0f, 0f)) // true
        };
        public AABB aabb = new AABB();

        public override void Intialize(int width, int height) {
            GL.Enable(EnableCap.DepthTest);
            GL.PointSize(5f);
            GL.PolygonMode(MaterialFace.FrontAndBack, PolygonMode.Line);

            aabb.Max = new Point(2, 2, 2);
            aabb.Min = new Point(-2, -2, -2);

            bool[] results = new bool[] { false, false, true, true };
            Point result = new Point();
            for (int i = 0; i < results.Length; ++i) {
                if (Collisions.LineTest(lines[i], aabb, out result) != results[i]) {
                    LogError("Line at index " + i + " was " +
                        (results[i] ? "expected" : "not expected") +
                        "to intersect the test aabb");
                }
            }
        }

        public override void Render() {
            base.Render();
            DrawOrigin();

            Point result = new Point();
            foreach (Line line in lines) {
                if (Collisions.LineTest(line, aabb, out result)) {
                    GL.Color3(1f, 0f, 1f);
                    result.Render();
                    GL.Color3(0f, 2f, 0f);
                }
                else {
                    GL.Color3(1f, 0f, 0f);
                }
                line.Render();
            }

            GL.Color3(0f, 0f, 1f);
            aabb.Render();
        }

        private void Log(string s) {
            System.Console.WriteLine(s);
        }
    }
}