import java.applet.Applet;
import java.awt.*;
import go.*;
import goText.*;


class Hello extends GoInterface
{
    String[] fontList = { "hersheyFonts/cursive",
                          "hersheyFonts/times.r",
                          "hersheyFonts/times.g",
                          "hersheyFonts/times.rb",
                          "hersheyFonts/times.i",
                          "hersheyFonts/times.ib",
                          "hersheyFonts/astrology",
                          "hersheyFonts/futura.m",
                          "hersheyFonts/greek",
                          "hersheyFonts/math.upp",
                          "hersheyFonts/symbolic",
                          "hersheyFonts/gothic.eng",
                          "hersheyFonts/japanese",
                          "hersheyFonts/meteorology",
                          "hersheyFonts/cyrillic",
                          "hersheyFonts/gothic.ger",
                          "hersheyFonts/markers",
                          "hersheyFonts/music",
                          "hersheyFonts/futura.l",
                          "hersheyFonts/gothic.ita",
                          "hersheyFonts/math.low",
                          "hersheyFonts/script" };

    final int FONT_NUM = fontList.length;
    
    GoText[] text = new GoText[FONT_NUM];

    int currentFont;  // font currently being displayed

    // View variables.
    double   eyeX, eyeY, eyeZ;
    double   centerX, centerY, centerZ;
    double   upX, upY, upZ;
    double   radius;
    boolean  perspective;

    Hello()
    {   
        //
        // Create "Hello World" with all the different fonts.
        //

        for(int i = 0; i < FONT_NUM; i++) {

            text[i] = new GoText(0.0, 0.0, 0.0,               /* position  */
                                 1.0, 0.0, 0.0,               /* path      */
                                 0.0, 1.0, 0.0,               /* up        */
                                 1.0, 1.0,                    /* scale     */
                                 GoText.CENTER_CENTER,        /* alignment */
                                 new GoHershey(fontList[i]),  /* font      */
                                 "Hello World");              /* text      */
        }
        currentFont = 0;

        //
        // Setup modelview matrix.
        //

        modelview();
    }

    //
    // Interface render method.
    //
    public void render()
    {
        go.clear(Go.IMAGE);
        text[currentFont].render(go);
        swap();

        go.rotate(2, 1, 1, 1);

        rerender();
    }

    //
    // Interface resized method.
    //
    public void resized(int width, int height)
    {
        projection();
    }

    //
    // Interface mousePressed method.
    //
    public void mousePressed(int x, int y)
    {
        nextFont();
        modelview();
        projection();
    }

    //
    // Set to next font in fontList.
    //
    void nextFont()
    {
        if(currentFont == FONT_NUM - 1) {
            currentFont = 0;
        }
        else {
            currentFont++;
        }
    }

    //
    // Sets up the modelview matrix.
    //
    void modelview()
    {
        //
        // Calculate the bounding box.
        //

        go.clear(Go.BOUND_BOX);
        go.renderMode(Go.BOUND_BOX);
        go.identity();
        text[currentFont].render(go);
        go.renderMode(Go.IMAGE);
        GoBoundBox boundBox = go.boundBox();
        
        //
        // Setup modelview variables.
        //

        double eyeMult = 3.0;
        
        eyeX        =  1.3 * eyeMult;
        eyeY        = -2.4 * eyeMult;
        eyeZ        =  2.0 * eyeMult;
        centerX     = (boundBox.xMin() + boundBox.xMax()) / 2.0;
        centerY     = (boundBox.yMin() + boundBox.yMax()) / 2.0;
        centerZ     = (boundBox.zMin() + boundBox.zMax()) / 2.0;
        upX         = 0.0;
        upY         = 0.0;
        upZ         = 1.0;
        radius      = distance(centerX, centerY, centerZ,
                               boundBox.xMax(), boundBox.yMax(), boundBox.zMax());
        perspective = true;
        
        //
        // Setup modelview matrix.
        //

        go.lookAt(eyeX, eyeY, eyeZ,
                  centerX, centerY, centerZ,
                  upX, upY, upZ);
    }

    //
    // Sets up the projection matrix.
    //
    void projection()
    {
        int width  = go.width();
        int height = go.height();

        double dx = eyeX - centerX;
        double dy = eyeY - centerY;
        double dz = eyeZ - centerZ;
        double d = Math.sqrt(dx * dx + dy * dy + dz * dz);
        
        double fovy = 2.0 * 180.0/Math.PI * Math.atan(radius / d);
        double near = d - radius;
        double far  = d + radius;
        
        double xUnits, yUnits;
        
        if(width >= height) {
            xUnits = 2 * radius * width / height;
            yUnits = 2 * radius;
        }
        else {
            xUnits = 2 * radius;
            yUnits = 2 * radius * height / width;
        }
        
        go.matrixMode(Go.PROJECTION);
        go.identity();
        if(perspective) {
            if(width >= height) {
                go.perspective(fovy, xUnits / yUnits, near, far);
            }
            else {
                double radiusModified = radius * yUnits / xUnits;
                double fovyModified = Math.atan(radiusModified / d) * 180.0 / Math.PI * 2.0;
                go.perspective(fovyModified, xUnits / yUnits, near, far);
            }
        }
        else {
            go.ortho(-xUnits / 2.0, xUnits / 2.0,
                     -yUnits / 2.0, yUnits / 2.0,
                     near, far);
        }
        go.matrixMode(Go.MODELVIEW);
    }

    //
    // Calculate distance between two points.
    //
    double distance(double x0, double y0, double z0,
                    double x1, double y1, double z1)
    {
        double dx = x1 - x0;
        double dy = y1 - y0;
        double dz = z1 - z0;
        
        return Math.sqrt(dx*dx + dy*dy + dz*dz);
    }
}

public class hello extends Applet
{
    public void init()
    {
        //
        // Fonts will be found relative to the html document
        // that includes this applet.
        //

        GoFont.path(getDocumentBase());

        //
        // Create Hello World.
        //

        setLayout(new GridLayout(1, 1));
        add(new Hello());
    }
}