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sanchiski
06-14-2012, 02:20 AM
I am trying to get the maximum texture size limit in Android for OpenGL ES 2.0. But I've found that the next instruction only works if I'm currently within the OpenGL context, in other words I must have a GL Surface and a GL Renderer created, and then ask for the texture size within the GLRenderer thread, all of which I don't need.


int[] maxTextureSize = new int[1];
GLES20.glGetIntegerv(GLES20.GL_MAX_TEXTURE_SIZE, maxTextureSize, 0);


So I came with the next algorithm, which gives me the maximum texture size without having to create any surface or renderer, or having to be in a different thread. It works correctly so far, so my questions are:

1) Area PBuffers always the same size as texture sizes
2) Can anyone spot any problem or anything I might have missed, just in case.



public int getMaximumTextureSize()
{
EGL10 egl = (EGL10)EGLContext.getEGL();
EGLDisplay display = egl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);

// Initialise
int[] version = new int[2];
egl.eglInitialize(display, version);

// Query total number of configurations
int[] totalConfigurations = new int[1];
egl.eglGetConfigs(display, null, 0, totalConfigurations);

// Query actual list configurations
EGLConfig[] configurationsList = new EGLConfig[totalConfigurations[0]];
egl.eglGetConfigs(display, configurationsList, totalConfigurations[0], totalConfigurations);

int[] textureSize = new int[1];
int maximumTextureSize = 0;

// Iterate through all the configurations to located the maximum texture size
for (int i = 0; i < totalConfigurations[0]; i++)
{
// Only need to check for width since opengl textures are always squared
egl.eglGetConfigAttrib(display, configurationsList[i], EGL10.EGL_MAX_PBUFFER_WIDTH, textureSize);

// Keep track of the maximum texture size
if (maximumTextureSize < textureSize[0])
{
maximumTextureSize = textureSize[0];
}

Log.i("GLHelper", Integer.toString(textureSize[0]));
}

// Release
egl.eglTerminate(display);
Log.i("GLHelper", "Maximum GL texture size: " + Integer.toString(maximumTextureSize));

return maximumTextureSize;
}

aqnuep
06-14-2012, 06:36 AM
1) Area PBuffers always the same size as texture sizes
There is no such guarantee, they can have completely different size limits

Further, what's the problem with creating a GL surface? You'll have to create a surface anyway if you want to call any of the GL functions.

sanchiski
06-14-2012, 01:03 PM
There is no such guarantee, they can have completely different size limits

Further, what's the problem with creating a GL surface? You'll have to create a surface anyway if you want to call any of the GL functions.

I don't need to use the GL surface at all, I only require to get the texture maximum size for informational purposes. And creating the sirface and renderer puts too much overlead.
So i guess there is no way around? I thought EGL is the API under the OpenGL layer, and such should give an option to get this information, but so far no luck.

aqnuep
06-14-2012, 01:11 PM
I don't need to use the GL surface at all, I only require to get the texture maximum size for informational purposes.
Well, I'd rather say invalid informational purposes then.


And creating the sirface and renderer puts too much overlead.
Does it? All applications, including the OpenGL Extensions Viewer or the GPU Caps Viewer figures out those hardware limitations, size limits, etc. by creating a context.
While I'm not aware of what is your application's purpose, I have to say that your approach won't be a generic one.


I thought EGL is the API under the OpenGL layer, and such should give an option to get this information, but so far no luck.
No, EGL is an API above the OpenGL layer, not under it. EGL is more or less like WGL or GLX, a way to access the "OpenGL layer" by creating a GL surface.

V-man
06-14-2012, 06:05 PM
It is pretty much the same issue with OpenGL as well --- you need a context to do anything
http://www.opengl.org/wiki/FAQ#What_is_an_OpenGL_context.3F