Fixing spring simulations and some write ups

1 files changed, 4 insertions, 3 deletions

diff --git a/2d/softbody/softbody_1/undamped.cpp b/2d/softbody/softbody_1/undamped.cpp
index 68e0636..578a126 100644
--- a/2d/softbody/softbody_1/undamped.cpp
+++ b/2d/softbody/softbody_1/undamped.cpp
@@ -150,9 +150,9 @@ namespace Undamped {
 
     void Spring::load(Renderer2d* renderer, SpringWeight* inWeight, float32 length, float32 initialDisplacement, float32 inK, float32 loopRadius) {
         weight = inWeight;
-	    position = initialDisplacement;
+	    position = -initialDisplacement;
         k = inK;
-		force = -k * initialDisplacement;
+		force = -k * position;
         velocity = sqrtf(k / weight->mass);
         
         const int32 verticesPerSegment = 6;
@@ -198,7 +198,8 @@ namespace Undamped {
     void Spring::update(float32 dtSeconds) {
 		float32 lastPosition = position;
 		force = -k * position;
-	    velocity = velocity + (force * dtSeconds) / weight->mass;
+        auto acceleration = (force / weight->mass);
+	    velocity = velocity + acceleration * dtSeconds;
 		position = position + velocity * dtSeconds;
 
 		float32 dx = position - lastPosition;