Fix GLTF animations (#4107)

Co-authored-by: Vito Tringolo <[email protected]>

1 files changed, 50 insertions, 0 deletions

diff --git a/src/raymath.h b/src/raymath.h
index 8b69cbd5..63947ee8 100644
--- a/src/raymath.h
+++ b/src/raymath.h
@@ -2525,4 +2525,54 @@ RMAPI int QuaternionEquals(Quaternion p, Quaternion q)
     return result;
 }
 
+// Decompose a transformation matrix into its rotational, translational and scaling components
+RMAPI void MatrixDecompose(Matrix mat, Vector3 *translation, Quaternion *rotation, Vector3 *scale)
+{
+    // Extract translation.
+    translation->x = mat.m12;
+    translation->y = mat.m13;
+    translation->z = mat.m14;
+
+    // Extract upper-left for determinant computation.
+    const float a = mat.m0;
+    const float b = mat.m4;
+    const float c = mat.m8;
+    const float d = mat.m1;
+    const float e = mat.m5;
+    const float f = mat.m9;
+    const float g = mat.m2;
+    const float h = mat.m6;
+    const float i = mat.m10;
+    const float A = e * i - f * h;
+    const float B = f * g - d * i;
+    const float C = d * h - e * g;
+
+    // Extract scale.
+    const float det = a * A + b * B + c * C;
+    float scalex = Vector3Length((Vector3) {a, b, c});
+    float scaley = Vector3Length((Vector3) {d, e, f});
+    float scalez = Vector3Length((Vector3) {g, h, i});
+    Vector3 s = {scalex, scaley, scalez};
+
+    if (det < 0) s = Vector3Negate(s);
+
+    *scale = s;
+
+    // Remove scale from the matrix if it is not close to zero.
+    Matrix clone = mat;
+    if (!FloatEquals(det, 0))
+    {
+        clone.m0 /= s.x;
+        clone.m5 /= s.y;
+        clone.m10 /= s.z;
+        // Extract rotation
+        *rotation = QuaternionFromMatrix(clone);
+    }
+    else
+    {
+        // Set to identity if close to zero
+        *rotation = QuaternionIdentity();
+    }
+}
+
 #endif  // RAYMATH_H