M 3G 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
