GLSL: how to define input and output properly

Spikx · 2009-10-20T18:38:59

Hello there, in the past I always used NVidia Cg for my Shaders in my applications. For a recent project we decided to switch to GLSL in order to try it out and learn it. I have a little bit of trouble adjusting to it. One thing I can't wrap my head around is how to define input and output data in a proper way. It seems GLSL is very "loose". If I writevarying vec3 lightDir;in both the vertex and the fragment shader, it seems its data is "magically" ;) available in both shaders. Anyway what I would like to hear from the GLSL users is, how you "properly" define your input and output variables. For instance, in Cg you can specifically assign the data of a hardware register to a variable. In Cg I always used structs likestruct a2v { float4 pos : POSITION; float3 normal : NORMAL; float2 texcoord : TEXCOORD0; float4 tangent : TEXCOORD1; float3 binormal : TEXCOORD2; };for the input of the vertex shader andstruct v2f { float4 color : COLOR0; float4 hpos : POSITION; float2 texcoord : TEXCOORD0; float3 vpos : TEXCOORD1; float3 normal : TEXCOORD2; float3 tangent : TEXCOORD3; float3 binormal : TEXCOORD4; float3 view : TEXCOORD5; float3 scale : TEXCOORD6; };for the input of the fragment shader, for example. But what is a good, clean and readable way to do the same in GLSL?