public void RayTriangleTest()
{
Vector3 origin = new Vector3(0, 0, 0);
Vector3 direction = new Vector3(1, 0, 0);
Ray r = new Ray(origin, direction);
Triangle t = new Triangle(
new Vertex() { Position = new Vector3(2, 1, 0) },
new Vertex() { Position = new Vector3(2, 0, -1) },
new Vertex() { Position = new Vector3(2, 0, 1) });
float time = -1f;
bool collides = r.CollidesWith(t, ref time);
Assert.True(collides);
Assert.Equal(2f, time);
Ray r2 = new Ray(origin, -direction);
collides = r2.CollidesWith(t, ref time);
Assert.False(collides);
Assert.Equal(-2f, time);
}
/// <summary>
/// Determines if a point has direct line of sight to a light, or if it is shadowed by another object
/// </summary>
/// <param name="pos">The position being checked</param>
/// <param name="light">The light source</param>
/// <returns>Whether or not the point is lit by the light or in a shadow</returns>
private bool InShadow(Vector3 pos, Light light)
{
// Get a vector from pos to light with some variation
Vector3 lightVec = light.Location
+ new Vector3(
(float)rand.NextDouble() * 2.0f * light.Radius - light.Radius,
(float)rand.NextDouble() * 2.0f * light.Radius - light.Radius,
(float)rand.NextDouble() * 2.0f * light.Radius - light.Radius)
- pos;
float lightDist = lightVec.Magnitude;
Ray shadowRay = new Ray(pos, lightVec);
float time = -1;
// Iterate over all the triangles in the scene to see if they block the light
foreach(var t in scene.Triangles)
{
if(shadowRay.CollidesWith(t, ref time))
{
if(time < lightDist && time > ProximityTolerance)
{
return true;
}
}
}
return false;
}
/// <summary>
/// Casts a ray and gets the resultant color
/// </summary>
/// <param name="r">The ray to cast</param>
/// <param name="depth">The current depth of the ray into the scene</param>
/// <param name="sourceTriangle">The source of the ray if it was reflected/refracted</param>
/// <returns>The resultant color of the ray</returns>
public Vector4 CastRay(Ray r, int depth = 0, Triangle sourceTriangle = null)
{
float closestTime = float.MaxValue;
Triangle closestTriangle = null;
Vector3 closestPosition = Vector3.Zero;
Vector4 returnColor = Vector4.Zero;
foreach (var t in scene.Triangles)
{
float time = float.MaxValue;
if (r.CollidesWith(t, ref time))
{
if (time < closestTime && time > ProximityTolerance)
{
closestTime = time;
closestTriangle = t;
closestPosition = r.PointAtDistance(time);
}
}
}
// If we can still cast rays deeper and we collided with an object, then cast more rays
if (depth < config.MaxRayDepth && closestTriangle != null)
{
// TODO: Cast reflection rays
// TODO: Cast refraction rays
// TODO: Add the color combinations from reflection and refraction
returnColor = GetColor(closestTriangle, closestPosition);
}
else if (closestTriangle != null)
{
returnColor = GetColor(closestTriangle, closestPosition);
}
return returnColor;
}