CODEWITHSUNDEEP
androidopengl-es
Werner
Werner

Reputation: 769

Android - open gl es 1.1 - drawing efficiency

Take an application containing a glSurfaceView which loads several separate images on start (GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0); for each image).

This application will then have to call gl.glBindTexture(GL10.GL_TEXTURE_2D, texture pointer int) before it can proceed to draw a different texture to a "texturable square" gl object.

Is it recommended to instead load one bitmap with all the textures (ie: a sprite sheet), and then create an array of "texturable squares" that each map a different area of the giant single image, like that gl.glBindTexture(...) only needs be called once...?

Or perhaps is there no significant difference between the two techniques?

Upvotes: 0

Views: 33

Answers (1)

Gil Moshayof
Gil Moshayof

Reputation: 16761

As far as I know, once a texture has been loaded via texImage2D, binding a texture is simply a matter of pointing the native OpenGL library to the correct preloaded texture, so performance wise, it shouldn't be costly.

However, you raise a good option which you should probably consider regardless of performance issues.

Normally, the textures you need don't have to be in power of two dimensions, but are set to that size anyway because of the requirements of OpenGL. This often results in a very wasteful memory allocation. Utilising "sprite sheets" as you put it can help save the time & memory of loading multiple bitmaps into textures which are usually larger than the parts you'll be rendering anyway.

For this reason, I would recommend using sprite sheets anyway, simply because it saves calls to texImage2D (which are quite costly), and potentially saves memory as well. If you properly manage the texture coordinates when switching between objects you want to render, this is the method I would recommend.

Upvotes: 1

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