Viewport size

OpenGL Development JOGL Development
#1

I am running Jogl on a Dell laptop with

GL_VENDOR: NVIDIA Corporation
GL_RENDERER: GeForce4 4200 Go/AGP/SSE2
GL_VERSION: 1.4.0
Maximum viewport dimension: (4096,4096) - obtained using gl.glGetIntegerv(gl.GL_MAX_VIEWPORT_DIMS,d);

Usually everything runs fast (30+ frames/sec). When I use a viewport bigger than 1024x1024 everything slows way down (less than 2 frames/sec). This happens even when I run the NVIDIA demos.

Any ideas (other than the obvious "don’t use a viewport bigger than 1Kx1K)?

Thanks.

#2

Have you tried with regular openGL apps to see if the same thing happens? (maybe just grab a simple demo from NeHe’s site or something).

Although the max is indicated as 4096x4096, it doesn’t mean its going to be fast at that speed. How much memory is there on a GF4 Go? It could that theres not enough memory for the double buffer so it has to use system ram instead.

#3

I have not tried any regular (non-java) opengl programs yet - the video card has 32 MBytes of memory.

#4

Which color depth do you use?

I sometimes have slowdown when I enable stencil buffer in 16bpp color mode on GeF 440 Go (Toshiba)

Yuri

#5

[quote]Which color depth do you use?

I sometimes have slowdown when I enable stencil buffer in 16bpp color mode on GeF 440 Go (Toshiba)

Yuri
[/quote]
nVidia cards don’t support stencil buffer useage with colour depths of 16bit and less. Typically they use a 32bit colour framebuffer with 24bit depth interleaved with 8 bit stencil.

Requesting stencil + 16bit colour will typically get you software rendering with an nVidia card because of this. The same is typically true of framebuffer alpha components, you need to be in 32bit mode or you get either 1bit alpha (ick) or a proper alpha channel emulated by software (and thus dog slow).

#6

This explaining some strange behavior - thanks.

Yuri

#7

I am in 32-bit mode.