M3G Performance Tips

M3G Performance Tips

 

Retained Mode

Use the retained mode

Do not render objects separately – place them in a world

Minimize the amount of Java code and method calls

Allows the implementation to do view frustum culling, etc

Keep node properties simple

Favor the T R S components over M

Avoid non-uniform scales in S

Avoid using the Alpha factor

 

Rendering Order

Use layers to impose a rendering order

Appearance contains a layer index (an Integer)

Defines a global ordering for submeshes & sprites

Can simplify shader state for backgrounds, overlays

Also enables multipass rendering in retained mode

Optimize the rendering order

Shader state sorting done by the implementation

Use layers to force back-to-front ordering

 

Textures

Use multitexturing to save in T&L and triangle setup

Use mipmapping to save in memory bandwidth

Combine small textures into texture atlases

Use the perspective correction hint (where needed )

       Usually much faster than increasing triangle count

       Nokia: 2% fixed overhead, 20% in worst case

 

Meshes

Minimize the number of objects

Per-mesh overhead is high, per-submesh also fairly high

Lots of small meshes and sprites to render --- bad

Ideally, everything would be in one big triangle strip

But then view frustum culling doesn’t work --- bad

Strike a balance

Merge simple meshes that are close to each other

Criteria for “simple” and “close” will vary by device

 

Shading State

Software vs. hardware implementations

SW: Minimize per-pixel operations

HW: Minimize shading state changes

HW: Do not mix 2D and 3D rendering

 

In general, OpenGL ES performances tips apply

 

Particle Effects                                                                      

Several Problems

Point sprites are not supported

Sprite3D are too much overhead

 

Put all particles in one Mesh

One particle == two triangles

All glued into one triangle strip

Update vertices to animate

       XYZ, RGB, maybe UV