Attribute and performance

i have a 40000 faces model, if i don’t use any shader or i use shaders without passing attribute framerate is perfect…but, if i pass two attibute (tangent e binormal–>6 float) to realize many shaders like dot3 bumping, frame rate goes down (below 15-10 fps), is it normal? i’m using radeon 9700 on Win2000,

perhaps try passing the normal/bitangent/tangent data with glTexCoord3f(…)

How many fps do you have when “framerate is perfect”?

I also had this issue with ATI ages ago. If I used any attributes as input to a vertex program the frame rate went way down. (I am almost cetain this has been fixed since)

A slightly newer bug I encountered months ago was when I passed everything as attributes, frame rate was so low it was software rendering. Turns out I needed to pass the position data in the fixed function way. Doing this, and passing all other data in attributes, frame-rate jumped up to the expected amount.

If i don’t pass any attribute i get a framerate of about 60 and up fps (with a 40000 faces mesh)…i’ve noticed that if i pass even only one float as attibute performance goes down and there is no difference between one attribute or five attributes, is it possible a problem at driver level?

Just a sanity check: how are you passing the model and the data?


I had a similar problem on my Radeon X800XT PE when passing float attributes. I solved it by passing vec3 attributes instead of float ones.

Does it help?

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