Draw a rotating 3D cube.

src/sig/Matrix.java

@@ -0,0 +1,23 @@
+package sig;
+
+import javax.vecmath.Vector3f;
+
+public class Matrix {
+    float[][] m = new float[4][4];
+    Matrix(float[][]m) {
+        this.m=m;
+    }
+
+    public static void MultiplyMatrixVector(Vector3f i,Vector3f o,Matrix m) {
+        o.x=i.x*m.m[0][0]+i.y*m.m[1][0]+i.z*m.m[2][0]+m.m[3][0];
+        o.y=i.x*m.m[0][1]+i.y*m.m[1][1]+i.z*m.m[2][1]+m.m[3][1];
+        o.z=i.x*m.m[0][2]+i.y*m.m[1][2]+i.z*m.m[2][2]+m.m[3][2];
+        float w=i.x*m.m[0][3]+i.y*m.m[1][3]+i.z*m.m[2][3]+m.m[3][3];
+
+        if (w!=0f) {
+            o.x/=w;
+            o.y/=w;
+            o.z/=w;
+        }
+    }
+}

src/sig/Mesh.java

@@ -0,0 +1,11 @@
+package sig;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Mesh {
+    List<Triangle> triangles = new ArrayList<>();
+    Mesh(List<Triangle> tris) {
+        this.triangles=tris;
+    }
+}

src/sig/Panel.java

@@ -2,6 +2,8 @@ package sig;
 import javax.swing.JPanel;
 import javax.vecmath.Vector3f;
 
+import sig.utils.DrawUtils;
+
 import java.awt.Graphics;
 import java.awt.Color;
 
@@ -22,6 +24,7 @@ public class Panel extends JPanel implements Runnable {
     private MemoryImageSource mImageProducer;   
     private ColorModel cm;    
     private Thread thread;
+    float fTheta=0f;
 
     public Panel() {
         super(true);
@@ -46,6 +49,8 @@ public class Panel extends JPanel implements Runnable {
         cm = getCompatibleColorModel();
         width = getWidth();
         height = getHeight();
+        SigRenderer.SCREEN_WIDTH=getWidth();
+        SigRenderer.SCREEN_HEIGHT=getHeight();
         int screenSize = width * height;
         if(pixel == null || pixel.length < screenSize){
             pixel = new int[screenSize];
@@ -64,6 +69,7 @@ public class Panel extends JPanel implements Runnable {
     */
     public /* abstract */ void render(){
         int[] p = pixel; // this avoid crash when resizing
+        //a=h/w
 
         final int h=SigRenderer.SCREEN_HEIGHT;
         if(p.length != width * height) return;        
@@ -75,6 +81,56 @@ public class Panel extends JPanel implements Runnable {
                 }
             }
         }   
+
+        Matrix matRotZ = new Matrix(new float[][]{
+            {(float)Math.cos(fTheta),(float)Math.sin(fTheta),0,0,},
+            {(float)-Math.sin(fTheta),(float)Math.cos(fTheta),0,0,},
+            {0,0,1,0,},
+            {0,0,0,1,},
+        }),matRotX = new Matrix(new float[][]{
+            {1,0,0,0,},
+            {0,(float)Math.cos(fTheta*0.5f),(float)Math.sin(fTheta*0.5f),0,},
+            {0,(float)-Math.sin(fTheta*0.5f),(float)Math.cos(fTheta*0.5f),0,},
+            {0,0,0,1,},
+        });
+        fTheta+=0.01f;
+
+        for (Triangle t : SigRenderer.cube.triangles) {
+            Triangle triProjected = new Triangle(new Vector3f(),new Vector3f(),new Vector3f()),triTranslated=new Triangle(new Vector3f(),new Vector3f(),new Vector3f()),triRotatedZ=new Triangle(new Vector3f(),new Vector3f(),new Vector3f()),triRotatedZX=new Triangle(new Vector3f(),new Vector3f(),new Vector3f());
+            
+
+            Matrix.MultiplyMatrixVector(t.A, triRotatedZ.A, matRotZ);
+            Matrix.MultiplyMatrixVector(t.B, triRotatedZ.B, matRotZ);
+            Matrix.MultiplyMatrixVector(t.C, triRotatedZ.C, matRotZ);
+            Matrix.MultiplyMatrixVector(triRotatedZ.A, triRotatedZX.A, matRotX);
+            Matrix.MultiplyMatrixVector(triRotatedZ.B, triRotatedZX.B, matRotX);
+            Matrix.MultiplyMatrixVector(triRotatedZ.C, triRotatedZX.C, matRotX);
+
+
+            triTranslated = (Triangle)triRotatedZX.clone();
+            triTranslated.A.z=triRotatedZX.A.z+3f;
+            triTranslated.B.z=triRotatedZX.B.z+3f;
+            triTranslated.C.z=triRotatedZX.C.z+3f;
+
+            Matrix.MultiplyMatrixVector(triTranslated.A, triProjected.A, SigRenderer.matProj);
+            Matrix.MultiplyMatrixVector(triTranslated.B, triProjected.B, SigRenderer.matProj);
+            Matrix.MultiplyMatrixVector(triTranslated.C, triProjected.C, SigRenderer.matProj);
+
+            triProjected.A.x+=1f;
+            triProjected.A.y+=1f;
+            triProjected.B.x+=1f;
+            triProjected.B.y+=1f;
+            triProjected.C.x+=1f;
+            triProjected.C.y+=1f;
+            triProjected.A.x*=0.5f*SigRenderer.SCREEN_WIDTH;
+            triProjected.A.y*=0.5f*SigRenderer.SCREEN_HEIGHT;
+            triProjected.B.x*=0.5f*SigRenderer.SCREEN_WIDTH;
+            triProjected.B.y*=0.5f*SigRenderer.SCREEN_HEIGHT;
+            triProjected.C.x*=0.5f*SigRenderer.SCREEN_WIDTH;
+            triProjected.C.y*=0.5f*SigRenderer.SCREEN_HEIGHT;
+
+            DrawUtils.DrawTriangle(p,(int)triProjected.A.x,(int)triProjected.A.y,(int)triProjected.B.x,(int)triProjected.B.y,(int)triProjected.C.x,(int)triProjected.C.y,Color.BLACK);
+        }
         i += 1;
         j += 1;    
         endTime=System.nanoTime();      

src/sig/SigRenderer.java

@@ -1,5 +1,6 @@
 package sig;
 import javax.swing.JFrame;
+import javax.vecmath.Matrix4f;
 import javax.vecmath.Point2d;
 import javax.vecmath.Tuple3d;
 import javax.vecmath.Vector3f;
@@ -9,14 +10,17 @@ import java.awt.event.MouseMotionListener;
 import java.awt.event.KeyEvent;
 import java.awt.event.KeyListener;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.awt.Toolkit;
 import java.awt.Color;
+import java.awt.Dimension;
+import java.awt.BorderLayout;
 
 public class SigRenderer implements KeyListener,MouseListener,MouseMotionListener{
-    public static Triangle tri,tri2,tri3,tri4,tri5,tri6;
+    public static Mesh cube;
-    public final static int SCREEN_WIDTH=1280;
+    public static int SCREEN_WIDTH=1280;
-    public final static int SCREEN_HEIGHT=720;
+    public static int SCREEN_HEIGHT=720;
     public final static long TIMEPERTICK = 16666667l;
     public static float DRAWTIME=0;
     public static float DRAWLOOPTIME=0;
@@ -27,21 +31,52 @@ public class SigRenderer implements KeyListener,MouseListener,MouseMotionListene
 
     public static List<Pixel> pixels;
 
+    public static float fNear = 0.1f;
+    public static float fFar = 1000f;
+    public static float fFov = 90f;
+    public static float fAspectRatio = (float)SCREEN_HEIGHT/SCREEN_WIDTH;
+    public static float fFovRad = 1f/(float)Math.tan(fFov*0.5f/180f*Math.PI);
+    public static Matrix matProj = new Matrix(
+        new float[][]{
+            {fAspectRatio*fFovRad,0,0,0},
+            {0,fFovRad,0,0},
+            {0,0,fFar/(fFar-fNear),1f},
+            {0,0,(-fFar*fNear)/(fFar-fNear),0f},
+        });
+
     public void runGameLoop() {
         rot+=Math.PI/480d;
     }
 
     SigRenderer(JFrame f) {
-
+        cube = new Mesh(Arrays.asList(
-        tri = new Triangle(new Vector3f(-1,-1,0),new Vector3f(0,-1,0),new Vector3f(-1,0,0));
+            new Triangle[]{
-        tri2 = new Triangle(new Vector3f(-1,0,0),new Vector3f(0,-1,0),new Vector3f(0,0,0));
+                new Triangle(new Vector3f(),new Vector3f(0,1,0),new Vector3f(1,1,0)),
-        tri3 = new Triangle(new Vector3f(0,0,0),new Vector3f(0,-1,0),new Vector3f(0,-1,-1));
+                new Triangle(new Vector3f(),new Vector3f(1,1,0),new Vector3f(1,0,0)),
-        tri4 = new Triangle(new Vector3f(0,-1,-1),new Vector3f(0,0,-1),new Vector3f(0,-1,0));
+                new Triangle(new Vector3f(1,0,0),new Vector3f(1,1,0),new Vector3f(1,1,1)),
-        /*tri5 = new Triangle(new Vector3f(0,-1,0),new Vector3f(0,-1,-1),new Vector3f(0,0,0));
+                new Triangle(new Vector3f(1,0,0),new Vector3f(1,1,1),new Vector3f(1,0,1)),
-        tri6 = new Triangle(new Vector3f(0,0,0),new Vector3f(0,-1,-1),new Vector3f(0,0,-1));*/
+                new Triangle(new Vector3f(0,1,0),new Vector3f(0,1,1),new Vector3f(1,1,0)),
+                new Triangle(new Vector3f(0,1,1),new Vector3f(1,1,1),new Vector3f(1,1,0)),
+                new Triangle(new Vector3f(),new Vector3f(0,0,1),new Vector3f(1,0,0)),
+                new Triangle(new Vector3f(0,0,1),new Vector3f(1,0,1),new Vector3f(1,0,0)),
+                new Triangle(new Vector3f(0,0,1),new Vector3f(0,1,1),new Vector3f(1,0,1)),
+                new Triangle(new Vector3f(0,1,1),new Vector3f(1,1,1),new Vector3f(1,0,1)),
+                new Triangle(new Vector3f(),new Vector3f(0,1,0),new Vector3f(0,0,1)),
+                new Triangle(new Vector3f(0,1,0),new Vector3f(0,1,1),new Vector3f(0,0,1)),
+            }));
 
         Panel p = new Panel();
 
+        f.getContentPane().addMouseListener(this);
+        f.getContentPane().addMouseMotionListener(this);
+        f.addKeyListener(this);
+        f.setSize(SCREEN_WIDTH,SCREEN_HEIGHT);
+        f.add(p,BorderLayout.CENTER);
+        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+        f.setVisible(true);
+        p.init();
+        
+
         new Thread() {
             public void run(){
                 while (true) {
@@ -67,15 +102,6 @@ public class SigRenderer implements KeyListener,MouseListener,MouseMotionListene
                 }
             }
         }.start();
-
-        f.getContentPane().addMouseListener(this);
-        f.getContentPane().addMouseMotionListener(this);
-        f.addKeyListener(this);
-        f.add(p);
-        f.setSize(SCREEN_WIDTH,SCREEN_HEIGHT);
-        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
-        f.setVisible(true);
-        p.init();
     }
     public static void main(String[] args) {
         JFrame f = new JFrame("SigRenderer");

src/sig/Triangle.java

@@ -9,6 +9,10 @@ public class Triangle {
         this.C=C;
     }
     @Override
+    protected Object clone(){
+        return new Triangle((Vector3f)this.A.clone(),(Vector3f)this.B.clone(),(Vector3f)this.C.clone());
+    }
+    @Override
     public String toString() {
         return "Triangle [A=" + A + ", B=" + B + ", C=" + C + "]";
     }

src/sig/utils/DrawUtils.java

@@ -0,0 +1,68 @@
+package sig.utils;
+
+import java.awt.Color;
+
+import sig.SigRenderer;
+
+public class DrawUtils {
+    public static void DrawTriangle(int[]canvas,int x1,int y1,int x2,int y2,int x3,int y3,Color col) {
+        DrawLine(canvas,x1,y1,x2,y2,col);
+        DrawLine(canvas,x2,y2,x3,y3,col);
+        DrawLine(canvas,x3,y3,x1,y1,col);
+    }
+    public static void DrawLine(int[] canvas,int x1,int y1,int x2,int y2,Color col) {
+        int x,y,dx,dy,dx1,dy1,px,py,xe,ye,i;
+        dx=x2-x1;dy=y2-y1;
+        dx1=Math.abs(dx);dy1=Math.abs(dy);
+        px=2*dy1-dx1;py=2*dx1-dy1;
+        if (dy1<=dx1) {
+            if (dx>=0) {
+                x=x1;y=y1;xe=x2;
+            } else {
+                x=x2;y=y2;xe=x1;
+            }
+            Draw(canvas,x,y,col);
+            for (i=0;x<xe;i++) {
+                x=x+1;
+                if (px<0) {
+                    px=px+2*dy1;
+                } else {
+                    if ((dx<0&&dy<0)||(dx>0&&dy>0)) {
+                        y=y+1;
+                    } else {
+                        y=y-1;
+                    }
+                    px=px+2*(dy1-dx1);
+                }
+                Draw(canvas,x,y,col);
+            }
+        } else {
+            if (dy>=0) {
+                x=x1;y=y1;ye=y2;
+            } else {
+                x=x2;y=y2;ye=y1;
+            }
+            Draw(canvas,x,y,col);
+            for (i=0;y<ye;i++) {
+                y=y+1;
+                if (py<=0) {
+                    py=py+2*dx1;
+                } else {
+                    if ((dx<0&&dy<0)||(dx>0&&dy>0)) {
+                        x=x+1;
+                    } else {
+                        x=x-1;
+                    }
+                    py=py+2*(dx1-dy1);
+                }
+                Draw(canvas,x,y,col);
+            }
+        }
+    }
+    public static void Draw(int[] canvas,int x,int y,Color col) {
+        if (x>=0&&y>=0&&x<SigRenderer.SCREEN_WIDTH&&y<SigRenderer.SCREEN_HEIGHT) {
+            //System.out.println(x+","+y);
+            canvas[x+y*SigRenderer.SCREEN_WIDTH]=col.getRGB();
+        }
+    }
+}