Imagination PowerVR SDK Blog

OpenGL Cube Shader Quality iOS Simulator vs iOSDev

#1

I have run across a quality problem using Apple  Mobile Devices like IPod, IPhone and even IPad and IPad2.

I am using Cube Mapping for the Environment Mapping of my Shader. The technique uses TangentSpace Normals to calculate the reflection dir in the fragment shader.

I’ve made sure that Cube Map Filters are set correctly that the precision in the shader is high enough and I even tried using Mipmaps, but the problem stays the same.

When using the Simulator the quality is fine, everything is nicely interpolated and there is no pixelation. When deploying the same to the devices everything is quite pixelated (see Images of Simulator and IPad Screenshots)

Is this simply a matter of the right settings or a technical issue, meaning the GPUs for mobile devices are still not that high quality.

I’ve not tested whether this issue is the same when using texture2D instead of cubemaps





#2

Hmm sorry I can’t add fotos


#3

I have tested now with texture2D as Environment Map, the Problem stays the same. The more distorted a texture gets (due to calculations in the shader like reflection or normalmapping) the more you will see this pixelation effect.

#4

Hi,





If you use the “Full Reply Editor” (^ there’s a button to launch it from the “Quick Reply” area), you can insert images using the “Insert Image” button. Note: This uses a link to where the image is hosted online, so you would have to upload the image elsewhere and use the http:// address to reference it.





Example:








Thanks,


Joe