Hi Processing Community,

I am having trouble applying a transparency effect to an OpenGL texture. The below example is the Textured Spere Example from the included OpenGL library with   tint(255,150);   added.

The problem I am experiencing is that allthough I turned lights off (noLights();) I get a sort of shadow on my Sphere, which, only makes half the sphere transparent and the other half not. When I rotate it, I can get the whole sphere transparent or totally non-transparent, depending on where I rotate.

The desired effect would be that the whole sphere is transparent, no matter where I rotate it.

Any ideas would be highly appreciated!

Thanks!

1. /**
    * Textured Sphere
    * by Mike 'Flux' Chang (cleaned up by Aaron Koblin).
    * Based on code by Toxi.
    *
    * A 3D textured sphere with simple rotation control.
    * Note: Controls will be inverted when sphere is upside down.
    * Use an "arc ball" to deal with this appropriately.
    */
   
   import processing.opengl.*;
   
   PImage bg;
   PImage texmap;
   
   int sDetail = 35;  // Sphere detail setting
   float rotationX = 0;
   float rotationY = 0;
   float velocityX = 0;
   float velocityY = 0;
   float globeRadius = 450;
   float pushBack = 0;
   
   float[] cx, cz, sphereX, sphereY, sphereZ;
   float sinLUT[];
   float cosLUT[];
   float SINCOS_PRECISION = 0.5;
   int SINCOS_LENGTH = int(360.0 / SINCOS_PRECISION);
   
   
   void setup() {
     size(1024, 768, OPENGL); 
     texmap = loadImage("world32k.jpg");   
     initializeSphere(sDetail);
   }
   
   void draw() {   
     background(0);           
     renderGlobe();
   }
   
   void renderGlobe() {
     pushMatrix();
     translate(width/2.0, height/2.0, pushBack);
     pushMatrix();
     noFill();
     stroke(255,200);
     strokeWeight(2);
     smooth();
     popMatrix();
     noLights();   
     pushMatrix();
     rotateX( radians(-rotationX) ); 
     rotateY( radians(270 - rotationY) );
     fill(255);
     noStroke();
    
     tint(255,150);
    
     textureMode(IMAGE); 
     texturedSphere(globeRadius, texmap);
     popMatrix(); 
     popMatrix();
     rotationX += velocityX;
     rotationY += velocityY;
     velocityX *= 0.95;
     velocityY *= 0.95;
    
     // Implements mouse control (interaction will be inverse when sphere is  upside down)
     if(mousePressed){
       velocityX += (mouseY-pmouseY) * 0.01;
       velocityY -= (mouseX-pmouseX) * 0.01;
     }
   }
   
   void initializeSphere(int res)
   {
     sinLUT = new float[SINCOS_LENGTH];
     cosLUT = new float[SINCOS_LENGTH];
   
     for (int i = 0; i < SINCOS_LENGTH; i++) {
       sinLUT[i] = (float) Math.sin(i * DEG_TO_RAD * SINCOS_PRECISION);
       cosLUT[i] = (float) Math.cos(i * DEG_TO_RAD * SINCOS_PRECISION);
     }
   
     float delta = (float)SINCOS_LENGTH/res;
     float[] cx = new float[res];
     float[] cz = new float[res];
    
     // Calc unit circle in XZ plane
     for (int i = 0; i < res; i++) {
       cx[i] = -cosLUT[(int) (i*delta) % SINCOS_LENGTH];
       cz[i] = sinLUT[(int) (i*delta) % SINCOS_LENGTH];
     }
    
     // Computing vertexlist vertexlist starts at south pole
     int vertCount = res * (res-1) + 2;
     int currVert = 0;
    
     // Re-init arrays to store vertices
     sphereX = new float[vertCount];
     sphereY = new float[vertCount];
     sphereZ = new float[vertCount];
     float angle_step = (SINCOS_LENGTH*0.5f)/res;
     float angle = angle_step;
    
     // Step along Y axis
     for (int i = 1; i < res; i++) {
       float curradius = sinLUT[(int) angle % SINCOS_LENGTH];
       float currY = -cosLUT[(int) angle % SINCOS_LENGTH];
       for (int j = 0; j < res; j++) {
         sphereX[currVert] = cx[j] * curradius;
         sphereY[currVert] = currY;
         sphereZ[currVert++] = cz[j] * curradius;
       }
       angle += angle_step;
     }
     sDetail = res;
   }
   
   // Generic routine to draw textured sphere
   void texturedSphere(float r, PImage t)
   {
     int v1,v11,v2;
     r = (r + 240 ) * 0.33;
     beginShape(TRIANGLE_STRIP);
     texture(t);
     float iu=(float)(t.width-1)/(sDetail);
     float iv=(float)(t.height-1)/(sDetail);
     float u=0,v=iv;
     for (int i = 0; i < sDetail; i++) {
       vertex(0, -r, 0,u,0);
       vertex(sphereX[i]*r, sphereY[i]*r, sphereZ[i]*r, u, v);
       u+=iu;
     }
     vertex(0, -r, 0,u,0);
     vertex(sphereX[0]*r, sphereY[0]*r, sphereZ[0]*r, u, v);
     endShape();  
    
     // Middle rings
     int voff = 0;
     for(int i = 2; i < sDetail; i++) {
       v1=v11=voff;
       voff += sDetail;
       v2=voff;
       u=0;
       beginShape(TRIANGLE_STRIP);
       texture(t);
       for (int j = 0; j < sDetail; j++) {
         vertex(sphereX[v1]*r, sphereY[v1]*r, sphereZ[v1++]*r, u, v);
         vertex(sphereX[v2]*r, sphereY[v2]*r, sphereZ[v2++]*r, u, v+iv);
         u+=iu;
       }
    
       // Close each ring
       v1=v11;
       v2=voff;
       vertex(sphereX[v1]*r, sphereY[v1]*r, sphereZ[v1]*r, u, v);
       vertex(sphereX[v2]*r, sphereY[v2]*r, sphereZ[v2]*r, u, v+iv);
       endShape();
       v+=iv;
     }
     u=0;
    
     // Add the northern cap
     beginShape(TRIANGLE_STRIP);
     texture(t);
     for (int i = 0; i < sDetail; i++) {
       v2 = voff + i;
       vertex(sphereX[v2]*r, sphereY[v2]*r, sphereZ[v2]*r, u, v);
       vertex(0, r, 0,u,v+iv);   
       u+=iu;
     }
     vertex(sphereX[voff]*r, sphereY[voff]*r, sphereZ[voff]*r, u, v);
     endShape();
    
   }