1 files changed, 57 insertions, 0 deletions
diff --git a/frontend/_shared/math/rigidbody2.js b/frontend/_shared/math/rigidbody2.js
new file mode 100644
index 0000000..0b18d0c
--- /dev/null
+++ b/frontend/_shared/math/rigidbody2.js
@@ -0,0 +1,57 @@
+/// <reference path="vec2.js" />
+/// <reference path="mat4.js" />
+/// <reference path="circle.js" />
+/// <reference path="line2.js" />
+/// <reference path="collision.js" />
+
+const GRAVITY = 9.8;
+const BYTES_PER_FLOAT = 4;
+
+/**
+ * 
+ * @param {Shape} pObject a 2D shape like a circle, rectangle, or line
+ * @param {Object} pData initial data for the rigidboy
+ */
+function makeRigidBody2(pObject, pData) {
+    pObject.velocity            = vec2();
+    pObject.prevVelocity        = pObject.velocity;
+    pObject.position            = pData.position || vec2();
+    pObject.prevPosition        = pObject.position;
+    pObject.force               = vec2();
+    pObject.rotationVelocity    = 0;
+    pObject.rotationRadians     = 0;
+    pObject.torque              = 0;
+    pObject.mass                = pData.mass !== undefined ? pData.mass : 1.0;
+    pObject.getMomentOfInertia  = pData.getMomentOfInertia;
+
+    return pObject;
+}
+
+function updateRigidBody2(pRigidbody, pDeltaTimeSeconds) {
+    applyForceRigidbody2(pRigidbody, vec2(0, -1.0 * (pRigidbody.mass * GRAVITY)));
+    const lCurrentAcceleration = scaleVec2(pRigidbody.force, 1.0 / pRigidbody.mass);
+    pRigidbody.prevVelocity = pRigidbody.velocity;
+    pRigidbody.velocity = addVec2(pRigidbody.velocity, scaleVec2(lCurrentAcceleration, pDeltaTimeSeconds));
+    pRigidbody.prevPos = { ...pRigidbody.position };
+    pRigidbody.position = addVec2(pRigidbody.position, scaleVec2(pRigidbody.velocity, pDeltaTimeSeconds));
+    pRigidbody.force = vec2();
+
+    const lMomentOfInertia =  pRigidbody.getMomentOfInertia(pRigidbody);
+    const lAngularAcceleration = pRigidbody.torque / lMomentOfInertia;
+    pRigidbody.rotationVelocity += lAngularAcceleration * pDeltaTimeSeconds;
+    pRigidbody.rotationRadians += pRigidbody.rotationVelocity * pDeltaTimeSeconds;
+    pRigidbody.torque = 0;
+
+    pRigidbody.model = rotateMatrix2d(translateMatrix(mat4(), pRigidbody.position.x, pRigidbody.position.y, 0), pRigidbody.rotationRadians);
+}
+
+function applyForceRigidbody2(pRigidbody, pForceVector, pPointOfApplication) {
+    if (pPointOfApplication !== undefined) {
+        const lOriginToPointOfApp = subVec2(vec2(), pPointOfApplication),
+            lPerpVec = vec2(-lOriginToPointOfApp.y, lOriginToPointOfApp.x);
+
+            pRigidbody.torque += TORQUE_MULTIPLIER * dot2(lPerpVec, pForceVector);
+    }
+
+    pRigidbody.force = addVec2(pRigidbody.force, pForceVector);
+}