Draw a cube with culling.

Co-authored-by: sigonasr2 <sigonasr2@gmail.com>

src/sig/Panel.java

@@ -112,6 +112,24 @@ public class Panel extends JPanel implements Runnable {
             triTranslated.B.z=triRotatedZX.B.z+3f;
             triTranslated.C.z=triRotatedZX.C.z+3f;
 
+            Vector3f normal=new Vector3f(),line1=new Vector3f(),line2=new Vector3f();
+            line1.x=triTranslated.B.x-triTranslated.A.x;
+            line1.y=triTranslated.B.y-triTranslated.A.y;
+            line1.z=triTranslated.B.z-triTranslated.A.z;
+            line2.x=triTranslated.C.x-triTranslated.A.x;
+            line2.y=triTranslated.C.y-triTranslated.A.y;
+            line2.z=triTranslated.C.z-triTranslated.A.z;
+
+            normal.x=line1.y*line2.z-line1.z*line2.y;
+            normal.y=line1.z*line2.x-line1.x*line2.z;
+            normal.z=line1.x*line2.y-line1.y*line2.x;
+
+            float l = (float)Math.sqrt(normal.x*normal.x+normal.y*normal.y+normal.z*normal.z);
+            normal.x/=l; normal.y/=l; normal.z/=l;
+
+            if (normal.x*(triTranslated.A.x-SigRenderer.vCamera.x)+
+                normal.y*(triTranslated.A.y-SigRenderer.vCamera.y)+
+                normal.z*(triTranslated.A.z-SigRenderer.vCamera.z)<0) {
                 Matrix.MultiplyMatrixVector(triTranslated.A, triProjected.A, SigRenderer.matProj);
                 Matrix.MultiplyMatrixVector(triTranslated.B, triProjected.B, SigRenderer.matProj);
                 Matrix.MultiplyMatrixVector(triTranslated.C, triProjected.C, SigRenderer.matProj);
@@ -131,6 +149,7 @@ public class Panel extends JPanel implements Runnable {
 
                 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

@@ -44,6 +44,8 @@ public class SigRenderer implements KeyListener,MouseListener,MouseMotionListene
             {0,0,(-fFar*fNear)/(fFar-fNear),0f},
         });
 
+    public static Vector3f vCamera = new Vector3f();
+
     public void runGameLoop() {
         rot+=Math.PI/480d;
     }
@@ -55,14 +57,14 @@ public class SigRenderer implements KeyListener,MouseListener,MouseMotionListene
                 new Triangle(new Vector3f(),new Vector3f(1,1,0),new Vector3f(1,0,0)),
                 new Triangle(new Vector3f(1,0,0),new Vector3f(1,1,0),new Vector3f(1,1,1)),
                 new Triangle(new Vector3f(1,0,0),new Vector3f(1,1,1),new Vector3f(1,0,1)),
-                new Triangle(new Vector3f(0,1,0),new Vector3f(0,1,1),new Vector3f(1,1,0)),
+                new Triangle(new Vector3f(1,0,1),new Vector3f(1,1,1),new Vector3f(0,1,1)),
-                new Triangle(new Vector3f(0,1,1),new Vector3f(1,1,1),new Vector3f(1,1,0)),
+                new Triangle(new Vector3f(1,0,1),new Vector3f(0,1,1),new Vector3f(0,0,1)),
-                new Triangle(new Vector3f(),new Vector3f(0,0,1),new Vector3f(1,0,0)),
+                new Triangle(new Vector3f(0,0,1),new Vector3f(0,1,1),new Vector3f(0,1,0)),
-                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(0,1,0),new Vector3f(0,0,0)),
-                new Triangle(new Vector3f(0,0,1),new Vector3f(0,1,1),new Vector3f(1,0,1)),
+                new Triangle(new Vector3f(0,1,0),new Vector3f(0,1,1),new Vector3f(1,1,1)),
-                new Triangle(new Vector3f(0,1,1),new Vector3f(1,1,1),new Vector3f(1,0,1)),
+                new Triangle(new Vector3f(0,1,0),new Vector3f(1,1,1),new Vector3f(1,1,0)),
-                new Triangle(new Vector3f(),new Vector3f(0,1,0),new Vector3f(0,0,1)),
+                new Triangle(new Vector3f(1,0,1),new Vector3f(0,0,1),new Vector3f(0,0,0)),
-                new Triangle(new Vector3f(0,1,0),new Vector3f(0,1,1),new Vector3f(0,0,1)),
+                new Triangle(new Vector3f(1,0,1),new Vector3f(0,0,0),new Vector3f(1,0,0)),
             }));
 
         Panel p = new Panel();

src/sig/Triangle.java

@@ -16,59 +16,4 @@ public class Triangle {
     public String toString() {
         return "Triangle [A=" + A + ", B=" + B + ", C=" + C + "]";
     }
-
-    public Vector3f getNormal() {
-        Vector3f AB = (Vector3f)A.clone();
-        AB.sub(B);
-        Vector3f BC = (Vector3f)B.clone();
-        BC.sub(C);
-        Vector3f crossP = new Vector3f();
-        crossP.cross(AB,BC);
-        //crossP.normalize();
-        return crossP;
-    }
-    public float distanceFromOrigin() {
-        return getNormal().dot(A);
-    }
-
-    public boolean rayTriangleIntersect(Vector3f origin,Vector3f dir) {
-        Vector3f N = getNormal();
-
-        float NrayDir = N.dot(dir);
-        if (NrayDir<=0.001) { //Very small, so it's parallel.
-            return false;
-        }
-
-        float d = distanceFromOrigin();
-
-        float T=(getNormal().dot(origin)+d)/(NrayDir);
-
-        if (T<0) {return false;} //Triangle is behind the ray.
-
-        //System.out.println("Not behind.");
-
-        Vector3f scaleMult = (Vector3f)dir.clone();
-        scaleMult.scale(T);
-        Vector3f P = (Vector3f)origin.clone();
-        P.add(scaleMult);
-
-        Vector3f C;
-
-        Vector3f edge0 = (Vector3f)B.clone(); edge0.sub(A);
-        Vector3f vp0 = (Vector3f)P.clone(); vp0.sub(A);
-        C = new Vector3f(); C.cross(edge0,vp0);
-        if (N.dot(C)<0) {return false;}
-
-        Vector3f edge1 = (Vector3f)this.C.clone(); edge1.sub(B);
-        Vector3f vp1 = (Vector3f)P.clone(); vp1.sub(B);
-        C = new Vector3f(); C.cross(edge1,vp1);
-        if (N.dot(C)<0) {return false;}
-
-        Vector3f edge2 = (Vector3f)A.clone(); edge2.sub(this.C);
-        Vector3f vp2 = (Vector3f)P.clone(); vp2.sub(this.C);
-        C = new Vector3f(); C.cross(edge2,vp2);
-        if (N.dot(C)<0) {return false;}
-
-        return true;
-    }
 }