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Textures

Mipmaps

Texture size is generally not a performance issue as long as a mipmap chain is present. Not providing mipmap chains, or not setting appropriate filter modes, will impact performance significantly.

When possible, it's recommended that you create mipmaps for all textures, and use an appropriate mip-selecting filter mode.

Go to Frame Debugger -> Texture Viewer.
Ensure All MipLevels is selected.
Scrub through all draw calls in the scene, verifying that mipmaps are present where appropriate. If a draw call uses multiple textures, check each in turn.

Texture Filter Modes

Bilinear filtering (within a single mip-level) is free on Tegra, trilinear comes with a (moderate) performance cost.

Use trilinear filtering only when necessary, to improve visual quality. This typically occurs on landscape meshes with large oblique polygons.

Tegra supports anisotropic filtering with up to 16 samples. It's recommended that anisotropic filtering be used only when absolutely necessary, to reduce visual artifacts.

Go to Frame Debugger -> State Viewer.
Open up the Texture Objects sub-hierarchy.
Scrub through all draw calls in the scene, verifying that, for each active texture:
- max anisotropy is set to some reasonable value (preferably 0),
- min filter is set to some mip-selecting filter mode (for example, not GL_LINEAR or GL_NEAREST).

Texture Formats

Texture fetch bandwidth can significantly impact performance. We support a wide range of compressed and single/dual channel texture formats to help reduce this load.

Use DXT1 for bulk assets with no alpha channel.
Use DXT5 for bulk assets with alpha.
Use single channel luminance/alpha textures for 1D look up tables.
Use dual channel luminance-alpha for 2D look up tables.
Only use the high-bandwidth 32bit rgba format to reduce specific visual artifacts.
We support fp16 2 and 4 channel formats, but recommend their use only when absolutely necessary.

Note that blanket use of 8/16bit component rgba format assets will impact performance considerably.

A high-level issue is identified in directed test.

Go to Frame Debugger -> Texture Viewer.
Scrub through all draw calls in the scene, verifying that texture assets are suitably compressed.

Dynamically Updated Textures

The presence of a possible performance issue here can be verified by looking at the dynamic texture indicator, in the dashboard. (Status bar, lower right).

To identify the specific drawcalls responsible for the issue, the same process used to identify VBO lock-down is required; see the section on Dynamically Modified VBO's.