From d3dae384497f61ad7eb1d9578db8860e6e6336aa Mon Sep 17 00:00:00 2001
From: ProfJski <49599659+ProfJski@users.noreply.github.com>
Date: Wed, 8 May 2019 13:54:12 -0400
Subject: [PATCH] Update CheckCollisionSpheres() to avoid sqrt

Square root calls are computationally expensive.  In this case, they can be avoided.  Instead of checking distance<RadA+RadB, check distance squared against (RadA+RadB) squared.  The dot product of Vector3Subtract(B,A) with itself gives distance squared, so I used this code instead of an element-by-element computation of distance squared.  The only downside is that your geometric code is very readable, whereas this is less so.
---
 src/models.c | 12 +-----------
 1 file changed, 1 insertion(+), 11 deletions(-)

diff --git a/src/models.c b/src/models.c
index c81dfe19..9e534a7c 100644
--- a/src/models.c
+++ b/src/models.c
@@ -2472,17 +2472,7 @@ void DrawBoundingBox(BoundingBox box, Color color)
 // Detect collision between two spheres
 bool CheckCollisionSpheres(Vector3 centerA, float radiusA, Vector3 centerB, float radiusB)
 {
-    bool collision = false;
-
-    float dx = centerA.x - centerB.x;      // X distance between centers
-    float dy = centerA.y - centerB.y;      // Y distance between centers
-    float dz = centerA.z - centerB.z;      // Y distance between centers
-
-    float distance = sqrtf(dx*dx + dy*dy + dz*dz);  // Distance between centers
-
-    if (distance <= (radiusA + radiusB)) collision = true;
-
-    return collision;
+    return Vector3DotProduct(Vector3Subtract(B,A),Vector3Subtract(B,A))<=(RadA+RadB)*(RadA+RadB);
 }
 
 // Detect collision between two boxes