using System;
using System.ComponentModel;
using SharpGL.SceneGraph.Core;
using SharpGL.SceneGraph.Lighting;
namespace SharpGL.SceneGraph.Core
{
/// <summary>
/// The ArcBall camera supports arcball projection, making it ideal for use with a mouse.
/// </summary>
[Serializable()]
public class ArcBall
{
/// <summary>
/// Initializes a new instance of the <see cref="PerspectiveCamera"/> class.
/// </summary>
public ArcBall()
{
// Set the identity matrices.
transformMatrix.SetIdentity();
lastRotationMatrix.SetIdentity();
thisRotationMatrix.SetIdentity();
}
/// <summary>
/// This is the class' main function, to override this function and perform a
/// perspective transformation.
/// </summary>
public void TransformMatrix(OpenGL gl)
{
gl.MultMatrix(transformMatrix.AsColumnMajorArray);
}
public void MouseDown(int x, int y)
{
// Map the start vertex.
MapToSphere((float)x, (float)y, out startVector);
}
public void MouseMove(int x, int y)
{
// todo need solid tuple types.
// Calculate the quaternion.
float[] quaternion = CalculateQuaternion(x, y);
thisRotationMatrix = Matrix3fSetRotationFromQuat4f(quaternion);
thisRotationMatrix = thisRotationMatrix * lastRotationMatrix;
Matrix4fSetRotationFromMatrix3f(ref transformMatrix, thisRotationMatrix); // Set Our Final Transform's Rotation From This One
}
public void MouseUp(int x, int y)
{
lastRotationMatrix.FromOtherMatrix(thisRotationMatrix, 3, 3);
thisRotationMatrix.SetIdentity();
//Matrix4fSetRotationFromMatrix3f(ref transformMatrix, thisRotationMatrix); // Set Our Final Transform's Rotation From This One
}
private Matrix Matrix3fSetRotationFromQuat4f(float[] q1)
{
float n, s;
float xs, ys, zs;
float wx, wy, wz;
float xx, xy, xz;
float yy, yz, zz;
n = (q1[0] * q1[0]) + (q1[1] * q1[1]) + (q1[2] * q1[2]) + (q1[3] * q1[3]);
s = (n > 0.0f) ? (2.0f / n) : 0.0f;
xs = q1[0] * s; ys = q1[1] * s; zs = q1[2] * s;
wx = q1[3] * xs; wy = q1[3] * ys; wz = q1[3] * zs;
xx = q1[0] * xs; xy = q1[0] * ys; xz = q1[0] * zs;
yy = q1[1] * ys; yz = q1[1] * zs; zz = q1[2] * zs;
Matrix matrix = new Matrix(3, 3);
matrix[0, 0] = 1.0f - (yy + zz); matrix[1, 0] = xy - wz; matrix[2, 0] = xz + wy;
matrix[0, 1] = xy + wz; matrix[1, 1] = 1.0f - (xx + zz); matrix[2, 1] = yz - wx;
matrix[0, 2] = xz - wy; matrix[1, 2] = yz + wx; matrix[2, 2] = 1.0f - (xx + yy);
return matrix;
}
private void Matrix4fSetRotationFromMatrix3f(ref Matrix transform, Matrix matrix)
{
float scale = transform.TempSVD();
transform.FromOtherMatrix(matrix, 3, 3);
transform.Multiply(scale, 3, 3);
}
private float[] CalculateQuaternion(int x, int y)
{
// Map the current vector.
MapToSphere((float)x, (float)y, out currentVector);
// Compute the cross product of the begin and end vectors.
Vertex cross = startVector.VectorProduct(currentVector);
// Is the perpendicular length essentially non-zero?
if (cross.Magnitude() > 1.0e-5)
{
// The quaternion is the transform.
return new float[] { cross.X, cross.Y, cross.Z, startVector.ScalarProduct(currentVector) };
}
else
{
// Begin and end coincide, return identity.
return new float[] { 0, 0, 0, 0 };
}
}
private void MapToSphere(float x, float y, out Vertex newVector)
{
float scaledX = x * adjustWidth - 1.0f;
float scaledY = 1.0f - y * adjustHeight;
// Get square of length of vector to point from centre.
float length = scaledX * scaledX + scaledY * scaledY;
// Are we outside the sphere?
if (length > 1.0f)
{
// Get normalising factor.
float norm = 1.0f / (float)Math.Sqrt(length);
// Return normalised vector, a point on the sphere.
newVector = new Vertex(-scaledX * norm, 0, scaledY * norm);
}
else
{
// Return a vector to a point mapped inside the sphere.
newVector = new Vertex(-scaledX, (float)Math.Sqrt(1.0f - length), scaledY);
}
}
public void SetBounds(float width, float height)
{
// Set the adjust width and height.
adjustWidth = 1.0f / ((width - 1.0f) * 0.5f);
adjustHeight = 1.0f / ((height - 1.0f) * 0.5f);
}
private float adjustWidth = 1.0f;
private float adjustHeight = 1.0f;
private Vertex startVector = new Vertex(0, 0, 0);
private Vertex currentVector = new Vertex(0, 0, 0);
Matrix transformMatrix = new Matrix(4, 4);
Matrix lastRotationMatrix = new Matrix(3, 3);
Matrix thisRotationMatrix = new Matrix(3, 3);
}
}
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