Newbie OpenGL Geometry shaders


I am using opengl v2.0.1.8x.
I am trying to apply a geometry shader to the rendering procedure.
The problem is very unusual (I’ve put a “// ****** Bug here”, before the problem codeline)

#version 120 
#extension GL_ARB_geometry_shader4 : enable
in vec3 vertWorldPos[3]; 
in vec3 vertWorldNormal[3]; 
out vec3 worldNormal; 
out vec3 worldPos; 
uniform vec2 WIN_SCALE; 
out vec3 dist; 

void main(void) { 
vec2 sz = WIN_SCALE;
vec2 tt = gl_PositionIn[0].xy;
vec2 t2 = vec2(gl_PositionIn[0].w, gl_PositionIn[0].w);
vec2 p0 = sz * tt / t2;  // ****** Bug here

tt = gl_PositionIn[1].xy;
t2 = vec2(gl_PositionIn[1].w, gl_PositionIn[1].w);
vec2 p1 = (sz * tt) / t2; // ****** Bug here

tt = gl_PositionIn[2].xy;
t2 = vec2(gl_PositionIn[2].w, gl_PositionIn[2].w);
vec2 p2 = (sz * tt) / t2; // ****** Bug here

vec2 v0 = p2-p1; 
vec2 v1 = p2-p0; 
vec2 v2 = p1-p0; 
float area = abs(v1.x*v2.y - v1.y * v2.x); // ****** Bug here

dist = vec3(area/length(v0),0,0); // ****** Bug here
worldPos = vertWorldPos[0]; 
worldNormal = vertWorldNormal[0]; 
gl_Position = gl_PositionIn[0]; 

dist = vec3(0,area/length(v1),0); // ****** Bug here
worldPos = vertWorldPos[1]; 
worldNormal = vertWorldNormal[1]; 
gl_Position = gl_PositionIn[1]; 

dist = vec3(0,0,area/length(v2)); // ****** Bug here
worldPos = vertWorldPos[2]; 
worldNormal = vertWorldNormal[2]; 
gl_Position = gl_PositionIn[2]; 


Thing is that it seems that the compilationcan not be applied on any code of line (in the geometry) where I am using the / or * operators…
Does anyone know what is wrong with that… and how to fix that?
I checked the version of the opengl I am using, but it seems that this code should work in the earlier versions as well (which I am using, I got quite old legacy “ATI Radeon x1650 GT” card).


#version 120 
#extension GL_ARB_geometry_shader4 : enable
in vec3 vertWorldPos[3]; 

First, these three statements cannot go together. GLSL 1.20 does not use in/out on global variables, and ARB_geometry_shader4 does not make this syntax legal. ARB_geometry_shader4 and core geometry shader functionality are specified differently. I would tell you how ARB_geometry_shader4 actually works, but:

I got quite old legacy “ATI Radeon x1650 GT” card

That card does not support geometry shaders. Of any kind. So it would be useless to explain.