Maximum Shadow Map Size

[isidisi]

How can I do, with Leadwerks Engine or OPENGL, to detect maximum shadow map size supported by a graphics card?

 

I want to set shadow map size to the maximum quality supported.

 

Thanks

[isidisi]

Maybe I can use glTexImage2D(GL_PROXY_TEXTURE_2D... OPENGL function, but I doesn't know the format of the shadow texture...

 

 

Any help????

[Canardia]

Maximum shadowmap size is the same as maximum texture size, and you can get it this way:

http://www.opengl.org/resources/faq/technical/texture.htm#text0120

[isidisi]

Maximum shadowmap size is the same as maximum texture size, and you can get it this way:

http://www.opengl.org/resources/faq/technical/texture.htm#text0120

 

 

yes glTexImage2D is the funcion I said to use, but what format is using Leadwerks to pass the right parameters to the function?

 

I tried with this code:

 

GLint testWidth = 256;

GLint resWidth;

 

while( true )

{

glTexImage2D(GL_PROXY_TEXTURE_2D, 0, GL_RGBA8, testWidth, testWidth, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);

glGetTexLevelParameteriv(GL_PROXY_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, &resWidth);

 

if (resWidth == 0 )

{

resWidth = testWidth / 2;

break;

}

else

{

testWidth *=2;

}

}

 

and I obtained than my maximum texture size is 16384

but Leadwerks engine hungs when I select a shadowmapsize of 4096 or higher... I think is because I didn't pass the right parameters...

[Canardia]

8192x8192 takes already 256MB of VRAM, 16384x16384 takes 1GB. And since LE needs mipmaps, they take about twice as much.

[isidisi]

I have debugged with glslDevil and I found that the call that Leadwerks is doing when I set ShadowmapSizeto 512 is:

 

glTexImage2D(GL_PROXY_TEXTURE_2D, 0, 33191, 1024, 1024, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);

 

if I set ShadowmapSizeto 1024 then I see in the debugger:

glTexImage2D(GL_PROXY_TEXTURE_2D, 0, 33191, 2048, 2048, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);

 

so always is creating a texture 2 * ShadowmapSize

 

Then we have to divide by 2 the max texture calculated in the routine I posted.

resWidth /= 2;

 

and replace the glTexImage2D call with

glTexImage2D(GL_PROXY_TEXTURE_2D, 0, 33191, testWidth, testWidth, 0, GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE, NULL);

 

 

Using 33191 and GL_DEPTH_COMPONENT as parameters, my max texture size is 8192, then my max shadomapsize is 4096.

I tried this with a simple program with a rotating cube and it's ok, works with 4096 and not with 8192 :-)

 

But if I load a big quantity of models the 4096 doesn't works anymore, I think as you say because then there's not enough memory to allocate both models and texture... but at least there's a way to detect max shadowmap size because of max texture size...

 

Thanks lumooja