/// <summary>
/// A <see cref="VertexArrayTexGenDelegate"/> mapping a sphere.
/// </summary>
/// <param name="v"></param>
/// <returns></returns>
public static Vertex2f SphereMap(Vertex3f v)
{
v.Normalize();
float x = (float)(Math.Atan2(v.z, v.x) / Math.PI) * 0.5f + 0.5f;
float y = (float)(Math.Asin(v.y) / (Math.PI / 2.0)) * 0.5f + 0.5f;
Debug.Assert(x >= 0.0f && x <= 1.0f);
Debug.Assert(y >= 0.0f && y <= 1.0f);
return(new Vertex2f(x, y));
}
/// <summary>
/// Generate the texture coordinate for the specified vertex.
/// </summary>
/// <param name="v"></param>
/// <returns></returns>
public override Vertex2f Generate(Vertex3f v)
{
v.Normalize();
float x = (float)(Math.Atan2(v.z, v.x) / Math.PI) * 0.5f + 0.5f;
float y = (float)(Math.Asin(v.y) / (Math.PI / 2.0)) * 0.5f + 0.5f;
Debug.Assert(x >= 0.0f && x <= 1.0f);
Debug.Assert(y >= 0.0f && y <= 1.0f);
return(new Vertex2f(x * Repeat.x, y * Repeat.y));
}
private void GenerateTangentsTriangle4f(IVertexArray positionArray, IVertexArray normalArray, IVertexArray texArray, IVertexArray tanArray, IVertexArray bitanArray)
{
uint count = (ElementCount != 0 ? ElementCount : _VertexArrayObject.ArrayLength) / 3;
for (uint i = 0, v = ElementOffset; i < count; i++, v += 3)
{
Vertex3f v0 = (Vertex3f)positionArray.GetElement <Vertex4f>(v);
Vertex3f v1 = (Vertex3f)positionArray.GetElement <Vertex4f>(v + 1);
Vertex3f v2 = (Vertex3f)positionArray.GetElement <Vertex4f>(v + 2);
Vertex2f t0 = texArray.GetElement <Vertex2f>(v);
Vertex2f t1 = texArray.GetElement <Vertex2f>(v + 1);
Vertex2f t2 = texArray.GetElement <Vertex2f>(v + 2);
Vertex3f dv1 = v1 - v0, dv2 = v2 - v0;
Vertex2f dt1 = t1 - t0, dt2 = t2 - t0;
float w = 1.0f / (dt1.x * dt2.y - dt1.y * dt2.x);
Vertex3f tgVector, btVector;
if (Single.IsInfinity(w) == false)
{
tgVector = (dv1 * dt2.y - dv2 * dt1.y) * w;
tgVector.Normalize();
btVector = (dv2 * dt1.x - dv1 * dt2.x) * w;
btVector.Normalize();
Vertex3f n = normalArray.GetElement <Vertex3f>(v).Normalized;
n.Normalize();
if (((n ^ tgVector) * btVector) < 0.0f)
{
tgVector = tgVector * -1.0f;
}
}
else
{
// Degenerate triangles does not contribute
tgVector = btVector = Vertex3f.Zero;
}
tanArray.SetElement <Vertex3f>(tgVector, v);
tanArray.SetElement <Vertex3f>(tgVector, v + 1);
tanArray.SetElement <Vertex3f>(tgVector, v + 2);
bitanArray.SetElement <Vertex3f>(btVector, v);
bitanArray.SetElement <Vertex3f>(btVector, v + 1);
bitanArray.SetElement <Vertex3f>(btVector, v + 2);
}
}
/// <summary>
/// Setup this matrix to view the universe in a certain direction.
/// </summary>
/// <param name="eyePosition">
/// A <see cref="Vertex3f"/> that specify the eye position, in local coordinates.
/// </param>
/// <param name="forwardVector">
/// A <see cref="Vertex3f"/> that specify the direction of the view. It will be normalized.
/// </param>
/// <param name="upVector">
/// A <see cref="Vertex3f"/> that specify the up vector of the view camera abstraction. It will be normalized
/// </param>
/// <returns>
/// It returns a view transformation matrix used to transform the world coordinate, in order to view
/// the world from <paramref name="eyePosition"/>, looking at <paramref name="forwardVector"/> having
/// an up direction equal to <paramref name="upVector"/>.
/// </returns>
public void LookAtDirection(Vertex3f eyePosition, Vertex3f forwardVector, Vertex3f upVector)
{
Vertex3f rightVector;
// Normalize forward vector
forwardVector.Normalize();
// Normalize up vector
upVector.Normalize();
// Compute the right vector (cross-product between forward and up vectors; right is perperndicular to the plane)
rightVector = forwardVector ^ upVector;
rightVector.Normalize();
// Derive up vector
upVector = rightVector ^ forwardVector;
upVector.Normalize();
// Compute view matrix
ModelMatrix lookatMatrix = new ModelMatrix(), positionMatrix = new ModelMatrix();
// Row 0: right vector
lookatMatrix[0, 0] = rightVector.x;
lookatMatrix[1, 0] = rightVector.y;
lookatMatrix[2, 0] = rightVector.z;
// Row 1: up vector
lookatMatrix[0, 1] = upVector.x;
lookatMatrix[1, 1] = upVector.y;
lookatMatrix[2, 1] = upVector.z;
// Row 2: opposite of forward vector
lookatMatrix[0, 2] = forwardVector.x;
lookatMatrix[1, 2] = forwardVector.y;
lookatMatrix[2, 2] = forwardVector.z;
// Eye position
positionMatrix.Translate(-eyePosition);
// Complete look-at matrix
Set(lookatMatrix * positionMatrix);
Set(GetInverseMatrix());
}
/// <summary>
/// Setup this matrix to view the universe in a certain direction.
/// </summary>
/// <param name="eyePosition">
/// A <see cref="Vertex3f"/> that specify the eye position, in local coordinates.
/// </param>
/// <param name="forwardVector">
/// A <see cref="Vertex3f"/> that specify the direction of the view. It will be normalized.
/// </param>
/// <param name="upVector">
/// A <see cref="Vertex3f"/> that specify the up vector of the view camera abstraction. It will be normalized
/// </param>
/// <returns>
/// It returns a view transformation matrix used to transform the world coordinate, in order to view
/// the world from <paramref name="eyePosition"/>, looking at <paramref name="forwardVector"/> having
/// an up direction equal to <paramref name="upVector"/>.
/// </returns>
public void LookAtDirection(Vertex3f eyePosition, Vertex3f forwardVector, Vertex3f upVector)
{
Vertex3f rightVector;
forwardVector.Normalize();
upVector.Normalize();
rightVector = forwardVector ^ upVector;
if (rightVector.Module() <= 0.0f)
{
rightVector = Vertex3f.UnitX;
}
rightVector.Normalize();
upVector = rightVector ^ forwardVector;
upVector.Normalize();
// Compute view matrix
ModelMatrix lookatMatrix = new ModelMatrix();
// Row 0: right vector
lookatMatrix[0, 0] = rightVector.x;
lookatMatrix[1, 0] = rightVector.y;
lookatMatrix[2, 0] = rightVector.z;
// Row 1: up vector
lookatMatrix[0, 1] = upVector.x;
lookatMatrix[1, 1] = upVector.y;
lookatMatrix[2, 1] = upVector.z;
// Row 2: opposite of forward vector
lookatMatrix[0, 2] = -forwardVector.x;
lookatMatrix[1, 2] = -forwardVector.y;
lookatMatrix[2, 2] = -forwardVector.z;
// Eye position
lookatMatrix.Translate(-eyePosition);
// Complete look-at matrix
Set(lookatMatrix);
}
/// <summary>
/// Setup this matrix to view the universe in a certain direction.
/// </summary>
/// <param name="eyePosition">
/// A <see cref="Vertex3f"/> that specify the eye position, in local coordinates.
/// </param>
/// <param name="forwardVector">
/// A <see cref="Vertex3f"/> that specify the direction of the view. It will be normalized.
/// </param>
/// <param name="upVector">
/// A <see cref="Vertex3f"/> that specify the up vector of the view camera abstraction. It will be normalized
/// </param>
/// <returns>
/// It returns a view transformation matrix used to transform the world coordinate, in order to view
/// the world from <paramref name="eyePosition"/>, looking at <paramref name="forwardVector"/> having
/// an up direction equal to <paramref name="upVector"/>.
/// </returns>
public void LookAtDirection(Vertex3f eyePosition, Vertex3f forwardVector, Vertex3f upVector)
{
Vertex3f rightVector;
// Normalize forward vector
forwardVector.Normalize();
// Normalize up vector
upVector.Normalize();
// Compute the right vector (cross-product between forward and up vectors; right is perperndicular to the plane)
rightVector = forwardVector ^ upVector;
rightVector.Normalize();
// Derive up vector
upVector = rightVector ^ forwardVector;
upVector.Normalize();
// Compute view matrix
ModelMatrix lookatMatrix = new ModelMatrix(), positionMatrix = new ModelMatrix();
// Row 0: right vector
lookatMatrix[0, 0] = rightVector.x;
lookatMatrix[1, 0] = rightVector.y;
lookatMatrix[2, 0] = rightVector.z;
// Row 1: up vector
lookatMatrix[0, 1] = upVector.x;
lookatMatrix[1, 1] = upVector.y;
lookatMatrix[2, 1] = upVector.z;
// Row 2: opposite of forward vector
lookatMatrix[0, 2] = forwardVector.x;
lookatMatrix[1, 2] = forwardVector.y;
lookatMatrix[2, 2] = forwardVector.z;
// Eye position
positionMatrix.Translate(-eyePosition);
// Complete look-at matrix
Set(lookatMatrix * positionMatrix);
Set(GetInverseMatrix());
}
