   Wierd problem with vertex shaders
  I've got a bunch of these little object scattered across a terrain. Normally they render fine, but when I try to apply a vertex shader (no fragment shader) to them wierd things start to happen. It looks like that for some of the objects the normals are going nuts, and the objects are switching from light to dark very quickly, but for other objects the normals work fine.Here's my vertex shader:void main(){gl_TexCoord[0] = gl_MultiTexCoord0;gl_Position = ftransform();gl_Normal = normalize(gl_NormalMatrix * gl_Normal);gl_FogFragCoord = gl_Position.z;}Seems simple enough. At this point I'm just trying to get it to look like it did with the fixed pipeline, but I can't even do that. What's going on?   
  I have discovered that the behavior of the shaders seems dependent on what shaders were bound earlier. But why is that? Can't you only have a single shader bound at a time? Why would that matter?   ;  is it possible you're setting some state in preparation for one vertex shader, and then you load the second part of the state is screwing with your second shader?  Because you can indeed only have one shader bound at once.  However, if you're mixing shading languages, ie you have ARBvp and then glsl vertex shaders, there may be some undefined behavior.  Thats my only thought, i'm sorry i cant be of more help.hope that helps-Dan   ;  I made up a truth table and tested every combination of shaders. I've got shaders for the terrain and plants (the plants are the ones doing the wierd stuff). The ONLY combination that produced the wierd results was the terrain fragment shader enabled, terrain vertex shader disabled, plant fragment shader disabled, and plant vertex shader enabled. In other words, it worked fine when rendering the plants using the fixed pipeline, OR when rendering the terrain with the fixed pipeline.I had my ideas about what was wrong, but this throws me off.Edit: btw, I'm rendering the plants immediately after rendering the terrain.   