arguments in ortho() refer to screen center

java/libraries/opengl/examples/Camera/NearFar/NearFar.pde

@@ -54,7 +54,7 @@ void draw() {
   if (usingPerspective) {
     perspective(cameraFOV, float(width)/float(height), cameraNear, cameraFar);
   } else {
-    ortho(0, width, 0, height, cameraNear, cameraFar);
+    ortho(-width/2, width/2, -height/2, height/2, cameraNear, cameraFar);
   }
 
   pushMatrix();

java/libraries/opengl/examples/Camera/OrthoVSPerspective/OrthoVSPerspective.pde

@@ -31,7 +31,7 @@ void draw()
     perspective(fov, float(width)/float(height), 
                 cameraZ/2.0, cameraZ*2.0); 
   } else {
-    ortho(0, width, 0, height, -200, +200);
+    ortho(-width/2, width/2, -height/2, height/2, 0, 400);
   }
   
   translate(width/2, height/2, 0);

java/libraries/opengl/examples/Lights/CameraLight/CameraLight.pde

@@ -16,11 +16,8 @@ void draw() {
   lights();
   
   if (mousePressed) {
-    // The arguments of ortho are specified in screen coordinates, where (0,0)
-    // is the upper left corner of the screen
-    ortho(0, width, 0, height);     
+    ortho(-width/2, width/2, -height/2, height/2);     
   } else {
-
     float fov = PI/3.0; 
     float cameraZ = (height/2.0) / tan(fov/2.0); 
     perspective(fov, float(width)/float(height), 

java/libraries/opengl/src/processing/opengl/PGraphicsOpenGL.java

@@ -3873,15 +3873,6 @@ public class PGraphicsOpenGL extends PGraphics {
                     float near, float far) {
     // Flushing geometry with a different perspective configuration.
     flush();
-
-    float halfw = 0.5f * (right - left);
-    float halfh = 0.5f * (top - bottom);
-
-    left -= halfw;
-    right -= halfw;
-
-    bottom -= halfh;
-    top -= halfh;
     
     float x = 2.0f / (right - left);
     float y = 2.0f / (top - bottom);