Resolves Issue#5958 3D orbitControl allowing +-90 degrees not enough.

src/webgl/p5.Camera.js

@@ -1720,23 +1720,21 @@ p5.Camera.prototype._orbit = function(dTheta, dPhi, dRadius) {
   let camTheta = Math.atan2(diffX, diffZ); // equatorial angle
   let camPhi = Math.acos(Math.max(-1, Math.min(1, diffY / camRadius))); // polar angle
 
-  // add change
-  camTheta += dTheta;
-  camPhi += dPhi;
-  camRadius += dRadius;
+  let newUpY = this.upY > 0 ? 1 : -1;
+  // add change according to the direction of newupY
+  camTheta += newUpY * dTheta;
+  camPhi += newUpY * dPhi;
+  // if camPhi becomes >= PI or <= 0,
+  // upY of camera need to be flipped to the other side
+  if (camPhi <= 0 || camPhi >= Math.PI) {
+    newUpY *= -1;
+  }
 
+  camRadius += dRadius;
   // prevent zooming through the center:
   if (camRadius < 0) {
     camRadius = 0.1;
   }
-
-  // prevent rotation over the zenith / under bottom
-  if (camPhi > Math.PI) {
-    camPhi = Math.PI;
-  } else if (camPhi <= 0) {
-    camPhi = 0.001;
-  }
-
   // from https://github.com/mrdoob/three.js/blob/dev/src/math/Vector3.js#L628-L632
   const _x = Math.sin(camPhi) * camRadius * Math.sin(camTheta);
   const _y = Math.cos(camPhi) * camRadius;
@@ -1750,7 +1748,7 @@ p5.Camera.prototype._orbit = function(dTheta, dPhi, dRadius) {
     this.centerY,
     this.centerZ,
     0,
-    1,
+    newUpY,
     0
   );
 };

test/unit/webgl/p5.Camera.js

@@ -449,34 +449,59 @@ suite('p5.Camera', function() {
 
       assert.deepEqual(myCam.cameraMatrix.mat4, expectedMatrix);
     });
-    test('_orbit() ensures altitude phi <= PI', function() {
+    test('_orbit() ensures myCam.upY switches direction (from 1 to -1) at camPhi <= 0', function() {
+      // the following should produce the upY with inverted direction(from 1 to -1)
+      // when camPhi changes from positive to negative or zero
+      myCam._orbit(0, -Math.PI, 0);
+      // upY should switch from 1(dPhi=0) to -1 (dPhi=-PI)
+      // myCam.upY should be -1
+      assert(myCam.upY === -1);
+    });
+    test('_orbit() ensures myCam.upY switches direction (from -1 to 1) at camPhi <= 0', function() {
+      // the following should produce the upY with inverted direction(from -1 to 1)
+      // when camPhi changes from negative to positive or zero
+      myCam._orbit(0, -Math.PI, 0);
+      myCam._orbit(0, Math.PI, 0);
+      // upY should switch from -1(dPhi=-PI) to 1 (dPhi=PI)
+      // myCam.upY should be 1
+      assert(myCam.upY === 1);
+    });
+    test('_orbit() ensures myCam.upY switches direction (from 1 to -1) at camPhi >= PI', function() {
+      // the following should produce the upY with inverted direction(from 1 to -1)
+      // when camPhi reaches PI
+      myCam._orbit(0, Math.PI, 0);
+      // upY should switch from 1(dPhi=0) to -1 (dPhi=PI)
+      // myCam.upY should be -1
+      assert(myCam.upY === -1);
+    });
+    test('_orbit() ensures myCam.upY switches direction (from -1 to 1) at camPhi >= PI', function() {
+      // the following should produce the upY with inverted direction(from -1 to 1)
+      // when camPhi reaches PI
+      myCam._orbit(0, Math.PI, 0);
+      myCam._orbit(0, -Math.PI, 0);
+      // upY should switch from -1(dPhi=PI) to 1 (dPhi=-PI)
+      // myCam.upY should be 1
+      assert(myCam.upY === 1);
+    });
+    test('_orbit() ensures camera can do multiple continuous 360deg rotations', function() {
+      // the following should produce two camera objects having same properties.
+      myCam._orbit(0, Math.PI, 0);
       var myCamCopy = myCam.copy();
-
-      // the following should produce the same values because phi is capped at PI
-      myCamCopy._orbit(0, 10, 0);
-      myCam._orbit(0, 20, 0);
-
-      assert.deepEqual(myCam.cameraMatrix.mat4, myCamCopy.cameraMatrix.mat4);
-    });
-    test('_orbit() ensures altitude phi > 0', function() {
-      var myCamCopy = myCam.copy();
-
-      // the following should produce the same values because phi is restricted
-      // to > 0
-      myCamCopy._orbit(0, -10, 0);
-      myCam._orbit(0, -20, 0);
-
-      assert.deepEqual(myCam.cameraMatrix.mat4, myCamCopy.cameraMatrix.mat4);
+      myCamCopy._orbit(0, Math.PI, 0);
+      myCamCopy._orbit(0, Math.PI, 0);
+      for (let i = 0; i < myCamCopy.cameraMatrix.mat4.length; i++) {
+        expect(
+          myCamCopy.cameraMatrix.mat4[i]).to.be.closeTo(
+          myCam.cameraMatrix.mat4[i], 0.001);
+      }
     });
     test('_orbit() ensures radius > 0', function() {
+      // the following should produce two camera objects having same properties.
+      myCam._orbit(0, Math.PI, 0);
       var myCamCopy = myCam.copy();
-
-      // the following should produce the same values because radius is
-      // restricted to > 0
-      myCamCopy._orbit(0, 0, -200);
-      myCam._orbit(0, 0, -300);
-
-      assert.deepEqual(myCam.cameraMatrix.mat4, myCamCopy.cameraMatrix.mat4);
+      myCamCopy._orbit(0, 0, -100);
+      myCam._orbit(0, 0, -250);
+      assert.deepEqual(myCam.cameraMatrix.mat4, myCamCopy.cameraMatrix.mat4, 'deep equal is failing');
     });
   });