Fixed Texture coordinates to account for perspective.

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

src/sig/Panel.java

@@ -17,6 +17,8 @@ import java.awt.GraphicsEnvironment;
 import java.awt.GraphicsConfiguration;
 import java.awt.Toolkit;
 
+import sig.Texture;
+
 public class Panel extends JPanel implements Runnable {
     long startTime = System.nanoTime();
     long endTime = System.nanoTime();
@@ -149,9 +151,20 @@ public class Panel extends JPanel implements Runnable {
                     triProjected.B = Matrix.MultiplyVector(SigRenderer.matProj,clipped[i].B);
                     triProjected.C = Matrix.MultiplyVector(SigRenderer.matProj,clipped[i].C);
                     triProjected.col = clipped[i].col;
-                    triProjected.T = clipped[i].T;
+                    triProjected.T = (Vector2)clipped[i].T.clone();
-                    triProjected.U = clipped[i].U;
+                    triProjected.U = (Vector2)clipped[i].U.clone();
-                    triProjected.V = clipped[i].V;
+                    triProjected.V = (Vector2)clipped[i].V.clone();
+
+                    triProjected.T.u = triProjected.T.u/triProjected.A.w;
+                    triProjected.U.u = triProjected.U.u/triProjected.B.w;
+                    triProjected.V.u = triProjected.V.u/triProjected.C.w;
+                    triProjected.T.v = triProjected.T.v/triProjected.A.w;
+                    triProjected.U.v = triProjected.U.v/triProjected.B.w;
+                    triProjected.V.v = triProjected.V.v/triProjected.C.w;
+
+                    triProjected.T.w = 1.0f/triProjected.A.w;
+                    triProjected.U.w = 1.0f/triProjected.B.w;
+                    triProjected.V.w = 1.0f/triProjected.C.w;
 
                     triProjected.A = Vector.divide(triProjected.A, triProjected.A.w);
                     triProjected.B = Vector.divide(triProjected.B, triProjected.B.w);
@@ -215,9 +228,9 @@ public class Panel extends JPanel implements Runnable {
 
             for (Triangle tt : triList) {
                 DrawUtils.TexturedTriangle(p, 
-                    (int)tt.A.x,(int)tt.A.y,tt.T.u,tt.T.v,
+                    (int)tt.A.x,(int)tt.A.y,tt.T.u,tt.T.v,tt.T.w,
-                    (int)tt.B.x,(int)tt.B.y,tt.U.u,tt.U.v,
+                    (int)tt.B.x,(int)tt.B.y,tt.U.u,tt.U.v,tt.U.w,
-                    (int)tt.C.x,(int)tt.C.y,tt.V.u,tt.V.v,
+                    (int)tt.C.x,(int)tt.C.y,tt.V.u,tt.V.v,tt.V.w,
                 SigRenderer.dirtTex);
                 if (SigRenderer.WIREFRAME) {
                     DrawUtils.DrawTriangle(p,(int)tt.A.x,(int)tt.A.y,(int)tt.B.x,(int)tt.B.y,(int)tt.C.x,(int)tt.C.y,Color.WHITE);

src/sig/SigRenderer.java

@@ -2,12 +2,9 @@ package sig;
 import javax.imageio.ImageIO;
 import javax.swing.JFrame;
 
-import sig.utils.OBJReader;
-
 import java.awt.event.MouseEvent;
 import java.awt.event.MouseListener; 
 import java.awt.event.MouseMotionListener;
-import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.IOException;
 import java.awt.event.KeyEvent;
@@ -45,7 +42,7 @@ public class SigRenderer implements KeyListener,MouseListener,MouseMotionListene
     final float MOVESPEED = 0.03f;
     final float TURNSPEED = 0.03f;
 
-    public static BufferedImage dirtTex;
+    public static Texture dirtTex;
 
     boolean upHeld=false,downHeld=false,leftHeld=false,rightHeld=false,
     aHeld=false,sHeld=false,dHeld=false,wHeld=false;
@@ -81,12 +78,7 @@ public class SigRenderer implements KeyListener,MouseListener,MouseMotionListene
     }
 
     SigRenderer(JFrame f) {
-
+        dirtTex = new Texture(new File("dirt.png"));
-        try {
-            dirtTex = ImageIO.read(new File("dirt.png"));
-        } catch (IOException e1) {
-            e1.printStackTrace();
-        }
 
         //cube = new Mesh(OBJReader.ReadOBJFile("teapot.obj"));
         cube = new Mesh(Arrays.asList(

src/sig/Texture.java

@@ -0,0 +1,30 @@
+package sig;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+
+import javax.imageio.ImageIO;
+import java.awt.Color;
+
+public class Texture{
+    BufferedImage tex;
+
+    public Texture(File f) {
+        try {
+            this.tex = ImageIO.read(f);
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public Color getColor(float u,float v) {
+        int sx = (int)(u*tex.getWidth()-1f);
+        int sy = (int)(v*tex.getHeight()-1f);
+        if (sx<0||sx>=tex.getWidth()||sy<0||sy>=tex.getHeight()) {
+            return new Color(0,0,0,0);
+        } else {
+            return new Color(tex.getRGB(sx,sy));
+        }
+    }
+    
+}

src/sig/Triangle.java

@@ -90,9 +90,11 @@ public class Triangle {
             out_tri[0].B = Vector.IntersectPlane(plane_p, plane_n, inside_points[0], outside_points[0],t);
             out_tri[0].U.u = t.t*(outside_tex[0].u-inside_tex[0].u)+inside_tex[0].u;
             out_tri[0].U.v = t.t*(outside_tex[0].v-inside_tex[0].v)+inside_tex[0].v;
+            out_tri[0].U.w = t.t*(outside_tex[0].w-inside_tex[0].w)+inside_tex[0].w;
             out_tri[0].C = Vector.IntersectPlane(plane_p, plane_n, inside_points[0], outside_points[1],t);
             out_tri[0].V.u = t.t*(outside_tex[1].u-inside_tex[0].u)+inside_tex[0].u;
             out_tri[0].V.v = t.t*(outside_tex[1].v-inside_tex[0].v)+inside_tex[0].v;
+            out_tri[0].V.w = t.t*(outside_tex[1].w-inside_tex[0].w)+inside_tex[0].w;
             return 1;
         } else
         if (insidePointCount==2&&outsidePointCount==1) {
@@ -105,6 +107,7 @@ public class Triangle {
             out_tri[0].C = Vector.IntersectPlane(plane_p, plane_n, inside_points[0], outside_points[0],t);
             out_tri[0].V.u = t.t*(outside_tex[0].u-inside_tex[0].u)+inside_tex[0].u;
             out_tri[0].V.v = t.t*(outside_tex[0].v-inside_tex[0].v)+inside_tex[0].v;
+            out_tri[0].V.w = t.t*(outside_tex[0].w-inside_tex[0].w)+inside_tex[0].w;
             out_tri[1].A = inside_points[1];
             out_tri[1].T = inside_tex[1];
             out_tri[1].B = out_tri[0].C;
@@ -112,6 +115,7 @@ public class Triangle {
             out_tri[1].C = Vector.IntersectPlane(plane_p, plane_n, inside_points[1], outside_points[0],t);
             out_tri[1].V.u = t.t*(outside_tex[0].u-inside_tex[1].u)+inside_tex[1].u;
             out_tri[1].V.v = t.t*(outside_tex[0].v-inside_tex[1].v)+inside_tex[1].v;
+            out_tri[1].V.w = t.t*(outside_tex[0].w-inside_tex[1].w)+inside_tex[1].w;
             return 2;
         }
 

src/sig/Vector.java

@@ -16,7 +16,7 @@ public class Vector {
     }
     @Override
     protected Object clone(){
-        return new Vector(x,y,z);
+        return new Vector(x,y,z,w);
     }
 
     public static Vector add(Vector v1,Vector v2) {

src/sig/Vector2.java

@@ -1,16 +1,20 @@
 package sig;
 
 public class Vector2 {
-    public float u,v;
+    public float u,v,w;
     Vector2() {
-        this(0,0);
+        this(0,0,1);
     }
     public Vector2(float u,float v) {
+        this(u,v,1);
+    }
+    public Vector2(float u,float v,float w) {
         this.u=u;
         this.v=v;
+        this.w=w;
     }
     @Override
     protected Object clone(){
-        return new Vector2(u,v);
+        return new Vector2(u,v,w);
     }
 }

src/sig/utils/DrawUtils.java

@@ -5,6 +5,7 @@ import java.util.Arrays;
 import java.awt.image.BufferedImage;
 
 import sig.SigRenderer;
+import sig.Texture;
 
 public class DrawUtils {
     static void drawLine(int[] canvas,int sx,int ex,int ny,Color col) {
@@ -13,36 +14,40 @@ public class DrawUtils {
         }
     }
     public static void TexturedTriangle(int[] canvas,
-            int x1, int y1, float u1,float v1,
+            int x1, int y1, float u1,float v1,float w1,
-            int x2, int y2, float u2,float v2,
+            int x2, int y2, float u2,float v2,float w2,
-            int x3, int y3, float u3,float v3,
+            int x3, int y3, float u3,float v3,float w3,
-            BufferedImage texture
+            Texture texture
     ) {
-		if (y2<y1) {int t=y1;y1=y2;y2=t;t=x1;x1=x2;x2=t;float u=u1;u1=u2;u2=u;float v=v1;v1=v2;v2=v;}
+		if (y2<y1) {int t=y1;y1=y2;y2=t;t=x1;x1=x2;x2=t;float u=u1;u1=u2;u2=u;float v=v1;v1=v2;v2=v;float w=w1;w1=w2;w2=w;}
-		if (y3<y1) {int t=y1;y1=y3;y3=t;t=x1;x1=x3;x3=t;float u=u1;u1=u3;u3=u;float v=v1;v1=v3;v3=v;}
+		if (y3<y1) {int t=y1;y1=y3;y3=t;t=x1;x1=x3;x3=t;float u=u1;u1=u3;u3=u;float v=v1;v1=v3;v3=v;float w=w1;w1=w3;w3=w;}
-		if (y3<y2) {int t=y2;y2=y3;y3=t;t=x2;x2=x3;x3=t;float u=u2;u2=u3;u3=u;float v=v2;v2=v3;v3=v;}
+		if (y3<y2) {int t=y2;y2=y3;y3=t;t=x2;x2=x3;x3=t;float u=u2;u2=u3;u3=u;float v=v2;v2=v3;v3=v;float w=w2;w2=w3;w3=w;}
 
         int dy1=y2-y1;
         int dx1=x2-x1;
         float dv1=v2-v1;
         float du1=u2-u1;
+        float dw1=w2-w1;
         int dy2=y3-y1;
         int dx2=x3-x1;
         float dv2=v3-v1;
         float du2=u3-u1;
-        float tex_u,tex_v;
+        float dw2=w3-w1;
+        float tex_u,tex_v,tex_w;
 
         float dax_step=0,dbx_step=0,
-            du1_step=0,dv1_step=0,
+            du1_step=0,dv1_step=0,dw1_step=0,
-            du2_step=0,dv2_step=0;
+            du2_step=0,dv2_step=0,dw2_step=0;
 
         if (dy1!=0) {dax_step=dx1/((float)Math.abs(dy1));}
         if (dy2!=0) {dbx_step=dx2/((float)Math.abs(dy2));}
 
         if (dy1!=0) {du1_step=du1/((float)Math.abs(dy1));}
         if (dy1!=0) {dv1_step=dv1/((float)Math.abs(dy1));}
+        if (dy1!=0) {dw1_step=dw1/((float)Math.abs(dy1));}
         if (dy2!=0) {du2_step=du2/((float)Math.abs(dy2));}
         if (dy2!=0) {dv2_step=dv2/((float)Math.abs(dy2));}
+        if (dy2!=0) {dw2_step=dw2/((float)Math.abs(dy2));}
 
         if (dy1!=0) {
             for (int i=y1;i<=y2;i++) {
@@ -51,17 +56,21 @@ public class DrawUtils {
 
                 float tex_su=u1+((float)(i-y1))*du1_step;
                 float tex_sv=v1+((float)(i-y1))*dv1_step;
+                float tex_sw=w1+((float)(i-y1))*dw1_step;
                 float tex_eu=u1+((float)(i-y1))*du2_step;
                 float tex_ev=v1+((float)(i-y1))*dv2_step;
+                float tex_ew=w1+((float)(i-y1))*dw2_step;
 
                 if (ax>bx) {
                     int t=ax;ax=bx;bx=t;
                     float u=tex_su;tex_su=tex_eu;tex_eu=u;
                     float v=tex_sv;tex_sv=tex_ev;tex_ev=v;
+                    float w=tex_sw;tex_sw=tex_ew;tex_ew=w;
                 }
 
                 tex_u=tex_su;
                 tex_v=tex_sv;
+                tex_w=tex_sw;
 
                 float tstep = 1.0f/((float)(bx-ax));
                 float t=0.0f;
@@ -69,7 +78,8 @@ public class DrawUtils {
                 for (int j=ax;j<bx;j++) {
                     tex_u=(1.0f-t)*tex_su+t*tex_eu;
                     tex_v=(1.0f-t)*tex_sv+t*tex_ev;
-                    Draw(canvas,j,i,new Color(texture.getRGB((int)Math.max(0,tex_u*(texture.getWidth()-1)),(int)Math.max(0,tex_v*(texture.getHeight()-1)))));
+                    tex_w=(1.0f-t)*tex_sw+t*tex_ew;
+                    Draw(canvas,j,i,texture.getColor(tex_u/tex_w,tex_v/tex_w));
                     t+=tstep;
                 }
             }
@@ -79,31 +89,37 @@ public class DrawUtils {
         dx1=x3-x2;
         dv1=v3-v2;
         du1=u3-u2;
+        dw1=w3-w2;
         if (dy1!=0) {dax_step=dx1/((float)Math.abs(dy1));}
         if (dy2!=0) {dbx_step=dx2/((float)Math.abs(dy2));}
         du1_step=0f;
         dv1_step=0f;
         if (dy1!=0) {du1_step=du1/((float)Math.abs(dy1));}
         if (dy1!=0) {dv1_step=dv1/((float)Math.abs(dy1));}
+        if (dy1!=0) {dw1_step=dw1/((float)Math.abs(dy1));}
 
         if (dy1!=0) {
             for (int i=y2;i<=y3;i++) {
-                int ax=(int)(x2+(float)(i-y2)*dax_step);
+                int ax=(int)(x2+((float)(i-y2))*dax_step);
-                int bx=(int)(x1+(float)(i-y1)*dbx_step);
+                int bx=(int)(x1+((float)(i-y1))*dbx_step);
 
                 float tex_su=u2+((float)(i-y2))*du1_step;
                 float tex_sv=v2+((float)(i-y2))*dv1_step;
+                float tex_sw=w2+((float)(i-y2))*dw1_step;
                 float tex_eu=u1+((float)(i-y1))*du2_step;
                 float tex_ev=v1+((float)(i-y1))*dv2_step;
+                float tex_ew=w1+((float)(i-y1))*dw2_step;
 
                 if (ax>bx) {
                     int t=ax;ax=bx;bx=t;
                     float u=tex_su;tex_su=tex_eu;tex_eu=u;
                     float v=tex_sv;tex_sv=tex_ev;tex_ev=v;
+                    float w=tex_sw;tex_sw=tex_ew;tex_ew=w;
                 }
 
                 tex_u=tex_su;
                 tex_v=tex_sv;
+                tex_w=tex_sw;
 
                 float tstep = 1.0f/((float)(bx-ax));
                 float t=0.0f;
@@ -111,7 +127,8 @@ public class DrawUtils {
                 for (int j=ax;j<bx;j++) {
                     tex_u=(1.0f-t)*tex_su+t*tex_eu;
                     tex_v=(1.0f-t)*tex_sv+t*tex_ev;
-                    Draw(canvas,j,i,new Color(texture.getRGB((int)Math.max(0,tex_u*(texture.getWidth()-1)),(int)Math.max(0,tex_v*(texture.getHeight()-1)))));
+                    tex_w=(1.0f-t)*tex_sw+t*tex_ew;
+                    Draw(canvas,j,i,texture.getColor(tex_u/tex_w,tex_v/tex_w));
                     t+=tstep;
                 }
             }