Convex Hull vs Mesh Collision Shapes in Blender

Understanding the difference between Convex Hull and Mesh collision shapes in Blender is essential for creating accurate and efficient physics simulations. While both define how rigid bodies interact and collide in 3D space, they fundamentally differ in how they process geometry, calculate surface boundaries, and consume computational resources. Convex Hull provides a simplified, highly optimized boundary suitable for most moving objects, whereas Mesh collision offers exact geometric accuracy required for concave surfaces and complex shapes.

What Is a Convex Hull Collision Shape?

A Convex Hull collision shape simplifies an object's geometry by wrapping it in an invisible, tight boundary—similar to shrink-wrapping the outermost vertices. It completely ignores any internal indentations, cavities, holes, or concave features. If an object has an indentation (such as the inside of a bowl or the hole in a donut), a Convex Hull will bridge the gap between the outermost points, making the hollow area solid to the physics engine.

Because the underlying math for calculating convex geometry is straightforward, Convex Hull is extremely performant and computationally lightweight. It is the default collision shape for rigid bodies in Blender and provides exceptional stability, preventing objects from snagging or jittering during dynamic simulations.

What Is a Mesh Collision Shape?

A Mesh collision shape (often called a Triangle Mesh) calculates collisions using the exact polygon geometry of the 3D model. Unlike Convex Hull, it reads every individual face, edge, and vertex, allowing the physics engine to recognize hollow interiors, sharp indentations, and complex concave structures.

This precision makes Mesh collision indispensable for objects like cups, tunnels, doorways, and terrain where other objects must pass through or rest inside concave regions. However, evaluating every polygon drastically increases calculation times and computational overhead. Additionally, fast-moving dynamic objects using Mesh collision can suffer from physics bugs, such as objects passing through each other or getting stuck.

Key Differences

• Geometry Handling: Convex Hull closes up all concave indentations to form a solid convex shape. Mesh collision preserves every polygon, including holes and cavities.
• Performance: Convex Hull requires minimal processing power, making it ideal for scenes with hundreds of colliding objects. Mesh collision is computationally demanding and can slow down simulation baking significantly.
• Physics Stability: Convex Hull is highly stable for moving (Dynamic) objects. Mesh collision is prone to instability and interpenetration when used on fast-moving dynamic bodies and is best reserved for stationary (Passive) objects.

When to Use Each Shape

• Use Convex Hull for almost all dynamic, moving debris, tumbling props, rocks, crates, and general scene objects where absolute interior precision is unnecessary.
• Use Mesh for static environments, hollow containers, landscape meshes, walls with cutouts, or any object that requires other rigid bodies to interact with its internal or concave geometry.