1 files changed, 67 insertions, 0 deletions
diff --git a/Build/source/utils/asymptote/webgl/arcball.js b/Build/source/utils/asymptote/webgl/arcball.js
new file mode 100644
index 00000000000..db6da0f81a0
--- /dev/null
+++ b/Build/source/utils/asymptote/webgl/arcball.js
@@ -0,0 +1,67 @@
+// double, double => rotation matrix
+// require https://cdn.rawgit.com/humbletim/glm-js/31fd034b/build/glm-js.min.js
+
+
+var arcballLib = {
+    arcball: function(oldmouse, newmouse) {
+        let oldMouseNew = [0, 0, 0];
+        let newMouseNew = [0, 0, 0];
+
+        let testNorm = this.twonorm(oldmouse);
+        if (testNorm > 1) {
+            oldMouseNew[0] = oldmouse[0] / testNorm;
+            oldMouseNew[1] = oldmouse[1] / testNorm;
+        } else {
+            oldMouseNew[0] = oldmouse[0];
+            oldMouseNew[1] = oldmouse[1];
+        }
+
+        let testNorm2 = this.twonorm(newmouse);
+        if (testNorm2 > 1) {
+            newMouseNew[0] = newmouse[0] / testNorm2;
+            newMouseNew[1] = newmouse[1] / testNorm2;
+        } else {
+            newMouseNew[0] = newmouse[0];
+            newMouseNew[1] = newmouse[1];
+        }
+
+        var z1squared = 1 - (oldMouseNew[1] ** 2) - (oldMouseNew[0] ** 2);
+        if (z1squared < 0 && z1squared > -0.00001) {
+            z1squared = 0;
+        }
+
+        var z2squared = 1 - (newMouseNew[1] ** 2) - (newMouseNew[0] ** 2);
+        if (z2squared < 0 && z2squared > -0.00001) {
+            z2squared = 0;
+        }
+
+
+        oldMouseNew[2] = Math.sqrt(z1squared);
+        newMouseNew[2] = Math.sqrt(z2squared);
+
+        if (isNaN(oldMouseNew[2]) || isNaN(newMouseNew[2])) {
+
+            alert('Error!');
+        }
+
+        
+        let oldMouseVec = glm.vec3(...oldMouseNew);
+        let newMouseVec = glm.vec3(...newMouseNew);
+        let axis = glm.normalize(glm.cross(oldMouseVec, newMouseVec));
+
+        // console.log(axis[0], axis[1], axis[2]);
+
+        let angle = Math.acos(glm.dot(oldMouseVec, newMouseVec));
+
+        return [angle, axis]
+
+    }, 
+
+    twonorm: function(v) {
+        let normSq = 0
+        for (let i = 0; i < v.length; i++) {
+            normSq += (v[i] ** 2);
+        }
+        return Math.sqrt(normSq);
+    }
+}
+\ No newline at end of file