//Contains common 3D stuff

import java.awt.*;
import graphics.Matrix3D;
import graphics.MatrixStack;

public class ThreeDApplet extends BufferedApplet
{
  long time0;
  double elapsed = 0; //# of seconds passed since start of applet

  int w, h;

  MatrixStack stack;

  //EXTEND THESE
  public void init() {
    super.init();

    w = bounds().width;
    h = bounds().height;

    time0 = System.currentTimeMillis(); //start the clock

    stack = new MatrixStack();
  }

  public void render(Graphics g) {
    elapsed = tick(); //set clock

    animate();
    draw(g);

    animating = true;
  }

  //OVERRIDE THESE
  void draw(Graphics g) {}
  void animate() {}

  public void drawShape(Graphics g, graphics.Shape s)
  {
    //loop through each face
    for (int fi = 0; fi < s.numFaces(); fi++)
    {
      int[] face = s.getFace(fi);

      //copy from vertices to points
      double[][] points = new double[face.length][6];
      for (int i = 0; i<face.length; i++)
        points[i] = s.getVertex(face[i]);

      if (face.length == 3) drawTriangle(g, points);
      else if (face.length == 4) drawQuad(g, points);
    }
  }

  public void drawTriangle(Graphics g, double[][] triangle)
  {
    //(0->1, 1->2, 2->0)
    g.drawLine( x(triangle[0][0]), y(triangle[0][1]),   x(triangle[1][0]), y(triangle[1][1]) );
    g.drawLine( x(triangle[1][0]), y(triangle[1][1]),   x(triangle[2][0]), y(triangle[2][1]) );
    g.drawLine( x(triangle[2][0]), y(triangle[2][1]),   x(triangle[0][0]), y(triangle[0][1]) );
  }

  //draws quad as two triangles
  public void drawQuad(Graphics g, double[][] quad)
  {
    double[][] triangle = new double[3][3]; //3 points with 3 values each

    //(0->1, 1->2, 2->0)
    triangle[0] = quad[0]; //1st point of triangle
    triangle[1] = quad[1]; //2nd point of triangle
    triangle[2] = quad[2]; //3rd point of triangle
    drawTriangle(g, triangle);

    //(2->3, 3->0, 0->2)
    triangle[0] = quad[2]; //1st point of triangle
    triangle[1] = quad[3]; //2nd point of triangle
    triangle[2] = quad[0]; //3rd point of triangle
    drawTriangle(g, triangle);
  }

  //projection stuff
  int x(double t) { return w/2 + (int)(t*w/4); }
  int y(double t) { return h/2 - (int)(t*w/4); }

  //returns the number of seconds passed since start of applet
  private double tick() {
    long time = System.currentTimeMillis();

    return (time - time0) / 1000.0;
  }

  //applies matrix at the top of the stack to a shape
  public void transform(graphics.Shape shape)
  {
    shape.matrix.copy(stack.peek());
    shape.transform();
  }

  //convenience methods for stack operations
  protected void push()
  {
    stack.push();
  }
  protected Matrix3D pop()
  {
    return stack.pop();
  }

  public void rotateX(double theta)
  {
    stack.peek().rotateX(theta);
  }
  public void rotateY(double theta)
  {
    stack.peek().rotateY(theta);
  }
  public void rotateZ(double theta)
  {
    stack.peek().rotateZ(theta);
  }
  public void translate(double x, double y, double z)
  {
    stack.peek().translate(x, y, z);
  }
  public void scale(double x, double y, double z)
  {
    stack.peek().scale(x, y, z);
  }
}