[Shocked] Hey its just a slider: FPS-10 because of moving a slider...

General Forums Blender and CG Discussions
1

Hi,

please have a short test:

  1. In the default scene, press N
  2. open “display”, and turn multitexture to GLSL, then change to textured mode
  3. press ALT+A
  4. pay attention to the fps-count in the upper left corner of the 3D-view
  5. move any material slider and watch how the fps drop drastically (the sliders lag!)

Come on…
This cant be…
Say this is just my computer, please!
Any setting I got wrong?

thanks in advance,
tillonius3002

2

I’m not getting any of that, fps is 24 (as set in the render settings). If i set the maximum to 60fps, it will intermittently jump to 54-ish when using the slider but it’s barely noticeable. I’m using 2.62 official release. What’s your graphics card?

3

2.62 official release. When I first start dragging the slider the FPS goes red for maybe a frame (not long enough to see what it drops to) but then I can slide the value around and it stays on 24. I would not notice a lag if I was not staring at the counter and if it didn’t change to red when it was under 24.

4

I would expect a framerate drop if the viewport shading mode is set to textured or solid w/ the “Textured solid” box checked in “display” (GLSL mode). However, I’m not really sure why there is a framerate drop when the viewport shading mode is set to wireframe in GLSL. That does indicate an area of future “optimization”.

I’m testing this on ancient hardware (>8 yrs old). I think you guys with newer hardware will not see as drastic of a drop as I am. I’m only getting ~ 12fps with a plane, a cube, and a light. If I change spec or diff sliders while animating the viewport (ALT+A), framerate drops to about 7 fps until I stop futzing with the slider.

Like I said… this still happens in wireframe mode where material setting should have nil effect on framerate.

5

If I move the slider from the left to the right it jumps in like 5 steps, if I move not too fast. It jumps to 13 fps (peak). I got a cycles ready (at least it can do that :D) nVidia GT540m. I have to mention, that I run Linux Mint 12.

Ah okay, you got me, I forgot it [sorry]. I thought that GLSL made no sense for wireframe, so that probably is why I didnt tell you to change to textured mode. My fault :frowning:

6

The reason there is a slowdown is because every time you change a material property in GLSL mode the vertex and fragment shaders are recompiled.
Since I haven’t spent much time with blenders drawing code I cannot tell you how easy it would be to optimize this.

7

blender is slow :frowning:

8

Having worked quite a lot with shaders in OpenGL, the idea that they’re recompiled on a simple parameter change is absolutely horrifying.

It’s trivial and fast to update data sent to shaders, it sounds like blenders drawing code needs help.

9

It’s not that simple unfortunately.
I’d suggest looking at the shadergen code in blenders gpu module to understand why shader recreation happens.