What is the maximum texture 'count' for ipad/3gs (SGX Graphics card)? how much memory we can use 'specifically' for texture data?

Question

What exactly is 'shared memory' related to texture memory in PowerVR SGX card.There is no proper documentation related to this.

Usually for an Application on iphone (assume 3gs/ipad PowerVR SGX cards)it is limited to use 24MB. Even if I load around 64mb of textures it will load.Then why its called shared memory! Really confused about this. Pointers to the whole architecture is also appreciated.thanks.

Answer 1

iPhone 3GS/4, iPod touch 3rd/4th generation, iPad/2 or later have PowerVR SGX GPU.

PowerVR SGX uses shared memory model with the main memory, so you can use textures of any size.

Imagination provides the brief documentations of PowerVR SGX.

• POWERVR SGX OpenGL ES 2.0 Application Development Recommendations
• POWERVR Series5 Graphics SGX architecture guide for developer

iPhone 3G and iPod touch 1st/2nd generation have PowerVR MBX (OLD).

Historically, the 1st and 2nd generation iPod touches used a PowerVR MBX (OLD). For the PowerVR MBX (OLD) the video memory was separated from the main memory, and the video memory size was 24MB. That memory was for back/front rendering buffer, textures and etc. Thus, you could not use textures over 24MB. This information is no longer relevant however. There are scarely any 24MB limited devices around today.

If you want to know further about it, May Apple's Instruments be with you.