/*******************************************************************************
 * Spin3d - Handles nice trackball style camera movement in Processing
 *   - based on Matrix3D code from cello3d by Marcello
 ********************************************************************************/

public class Spin3d {
  float x= 0, y = 0;
  float tdx = 0, tdy = 0;
  float dx = tdx, dy = tdy;

//int pmouseX,pmouseY;
  public void mouseMoved() {
    // GOTCHA: x and y are switched!
    tdx=(mouseY-pmouseY);
    tdy=(mouseX-pmouseX);
//    pmouseX=mouseX;
//    pmouseY=mouseY;
  }
  public void apply() {
    ((PGraphics3)g).
    applyMatrix(m_0_0, m_0_1, m_0_2, m_0_3,
                m_1_0, m_1_1, m_1_2, m_1_3,
                m_2_0, m_2_1, m_2_2, m_2_3,
                m_3_0, m_3_1, m_3_2, m_3_3);
  }
  void update() {
    x += dx;
    y += dy;
    dx += (tdx-dx)/20;
    dy += (tdy-dy)/20;
    tdx += (0-tdx)/20;
    tdy += (0-tdy)/20;
    rotateX(dx);
    rotateY(dy);
  }

	public Spin3d() {
	}
	public float	
		m_0_0 = 1, m_0_1 = 0, m_0_2 = 0, m_0_3 = 0,
		m_1_0 = 0, m_1_1 = 1, m_1_2 = 0, m_1_3 = 0,
		m_2_0 = 0, m_2_1 = 0, m_2_2 = 1, m_2_3 = 0,
		m_3_0 = 0, m_3_1 = 0, m_3_2 = 0, m_3_3 = 1;

	public void rotateX(float t) {
		if (t==0) return;
		float sin = sin(t);
		float cos = cos(t);
		transform(
			1,    0,   0,   0,
			0,    cos, sin, 0,
			0,    -sin,cos, 0,
			0,    0,   0,   1
		);
	}
	public void rotateY(float t) {
		if (t==0) return;
		float sin = sin(t);
		float cos = cos(t);
		transform(
			cos, 0,   sin, 0,
			0,   1,   0,   0,
			-sin,0,   cos, 0,
			0,   0,   0,   1
		);
	}
	
	public void transform(float nm_0_0, float nm_0_1, float nm_0_2, float nm_0_3,
						float nm_1_0, float nm_1_1, float nm_1_2, float nm_1_3,
						float nm_2_0, float nm_2_1, float nm_2_2, float nm_2_3,
						float nm_3_0, float nm_3_1, float nm_3_2, float nm_3_3) {
							
		Spin3d m =  new Spin3d();

		m.m_0_0 = m_0_0; m.m_0_1 = m_0_1; m.m_0_2 = m_0_2; m.m_0_3 = m_0_3;
		m.m_1_0 = m_1_0; m.m_1_1 = m_1_1; m.m_1_2 = m_1_2; m.m_1_3 = m_1_3;
		m.m_2_0 = m_2_0; m.m_2_1 = m_2_1; m.m_2_2 = m_2_2; m.m_2_3 = m_2_3;
		m.m_3_0 = m_3_0; m.m_3_1 = m_3_1; m.m_3_2 = m_3_2; m.m_3_3 = m_3_3;

		m_0_0 = nm_0_0*m.m_0_0 + nm_0_1*m.m_1_0 + nm_0_2*m.m_2_0;
		m_0_1 = nm_0_0*m.m_0_1 + nm_0_1*m.m_1_1 + nm_0_2*m.m_2_1;
		m_0_2 = nm_0_0*m.m_0_2 + nm_0_1*m.m_1_2 + nm_0_2*m.m_2_2;
		m_0_3 = nm_0_0*m.m_0_3 + nm_0_1*m.m_1_3 + nm_0_2*m.m_2_3 + nm_0_3;
		m_1_0 = nm_1_0*m.m_0_0 + nm_1_1*m.m_1_0 + nm_1_2*m.m_2_0;
		m_1_1 = nm_1_0*m.m_0_1 + nm_1_1*m.m_1_1 + nm_1_2*m.m_2_1;
		m_1_2 = nm_1_0*m.m_0_2 + nm_1_1*m.m_1_2 + nm_1_2*m.m_2_2;
		m_1_3 = nm_1_0*m.m_0_3 + nm_1_1*m.m_1_3 + nm_1_2*m.m_2_3 + nm_1_3;
		m_2_0 = nm_2_0*m.m_0_0 + nm_2_1*m.m_1_0 + nm_2_2*m.m_2_0;
		m_2_1 = nm_2_0*m.m_0_1 + nm_2_1*m.m_1_1 + nm_2_2*m.m_2_1;
		m_2_2 = nm_2_0*m.m_0_2 + nm_2_1*m.m_1_2 + nm_2_2*m.m_2_2;
		m_2_3 = nm_2_0*m.m_0_3 + nm_2_1*m.m_1_3 + nm_2_2*m.m_2_3 + nm_2_3;
	}
}