// mas964 ps2
// draw triangles on mouse click that demonstrate variety

import java.applet.*;
import java.awt.*;
import java.lang.Math;
import DoubleBufferApplet;

// this code really only works for 300x300 applet windows.
// it should be fixed.
public class TriangleVariety extends DoubleBufferApplet {
  protected int leftMargin, topMargin;
  protected int numTriangles;
  protected int triangleSize = 26;		  // should be even

  protected double c[][][];

  // all these constants are used to randomize the triangle drawing
  public void randomizeConstants() {
    int i, j, k;
    for (i = 0; i < numTriangles; i++)
      for (j = 0; j < numTriangles - i; j++)	  // only generate a triangle
	for (k = 0; k < 6; k++)
	  c[i][j][k] = Math.random();
  }
  
  // draw a bunch of triangles in a triangular shape
  // the triangles are randomly varied from their centers depending
  // on the mouseclick. Further right == more X variation, and futher
  // down is more Y variation.
  // randomization is precalculated so state is preserved (for drags)
  public void redrawTriangles(int mouseX, int mouseY) {
    Graphics g = imageBuffer.getGraphics();
      
    this.clearImageBuffer();
    g.setColor(this.getForeground());

    int x, y;
    for (y = 0; y < numTriangles; y++)
      for (x = 0; x < numTriangles - y; x++) {
	int screenX, screenY;

	screenY = topMargin + y * triangleSize;
	screenX = leftMargin + y * triangleSize / 2 + x * triangleSize;

	int a = triangleSize * mouseX / imageBufferSize.width;  // variety in x
	int b = triangleSize * mouseY / imageBufferSize.height; // variety in y
	fillTriangle(g,
		     screenX + (int)(c[y][x][0] * 2*a - a),
		     screenY + (int)(c[y][x][1] * 2*b - b),
		     screenX + triangleSize + (int)(c[y][x][2] * 2*a - a),
		     screenY + (int)(c[y][x][3] * 2*b - b),
		     screenX + triangleSize / 2 + (int)(c[y][x][4] * 2*a - a),
		     screenY + triangleSize + (int)(c[y][x][5] * 2*b - b));
      }
    repaint();
  }

  // should really be an extension to Graphics, but how do you do that?
  public void drawTriangle(Graphics g,
			   int x1, int y1, int x2, int y2, int x3, int y3) {
    int x[] = { x1, x2, x3, x1 };
    int y[] = { y1, y2, y3, y1 };
    g.drawPolygon(x, y, 4);			  // should be 3 points?!
  }

  public void fillTriangle(Graphics g,
			   int x1, int y1, int x2, int y2, int x3, int y3) {
    int x[] = { x1, x2, x3 };
    int y[] = { y1, y2, y3 };
    g.fillPolygon(x, y, 3);
  }

  // figure out how many triangles will fit.
  public void reshape(int x, int y, int width, int height) {
    int minDimension = Math.min(height, width);
    numTriangles = (minDimension / triangleSize) - 1;
    topMargin = (height - numTriangles * triangleSize) / 2;
    leftMargin = (width - numTriangles * triangleSize) / 2;
    // System.out.println("Drawing " + numTriangles + " triangles starting at " + topMargin + "," + leftMargin);
    c = new double[numTriangles][numTriangles][6];
    super.reshape(x, y, width, height);
  }
    
  public boolean mouseDown(Event e, int mouseX, int mouseY) {
    randomizeConstants();
    redrawTriangles(mouseX, mouseY);
    return true;
  }
  
  public boolean mouseDrag(Event e, int mouseX, int mouseY) {
    redrawTriangles(mouseX, mouseY);
    return true;
  }

  public void init() {
    this.setBackground(Color.white);
    this.setForeground(Color.black);
    super.init();
  }
}