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judge dreadz

Please look at this Cg shader

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Ok, i'm just starting out trying to learn Cg. Here is the shader i wrote:
struct vShader1Out {
	float4 position : POSITION;
	float4 color	: COLOR;
};

vShader1Out vShader1(float2 position : POSITION)
{
	vShader1Out OUT;
	OUT.position = float4(position, 0, 1);
	OUT.color    = float4(1, 0, 0, 1);
	return OUT;
}

This is basically the same as the first shader from the Cg tutorial book. I draw a square in openGL, and then pass the position paramater to the shader. I expected only the color of the square to be changed to red, but when i run it the square is a different size and in a different place. does anyone know whats causing this? Here is the openGL code i wrote:
#include <GL/glut.h>
#include <GL/gl.h>
#include <Cg/cg.h>      
#include <Cg/cgGL.h>    

CGcontext cgContext;
CGprogram vShader;
CGparameter positionParam;

CGprofile vProfile = CG_PROFILE_VP20;

void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT);    
    glBegin(GL_QUADS);
        glVertex2f(0.25, 0.25);
        glVertex2f(0.75, 0.25);
        glVertex2f(0.75, 0.75);
        glVertex2f(0.25, 0.75);
    glEnd();
    glFlush();
}

void init(void)
{
    // initialise GL
    glClearColor(0,0,0,0);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);

    // initialise Cg
    cgContext = cgCreateContext();
    vShader = cgCreateProgramFromFile(cgContext, CG_SOURCE, "vShader1.cg", vProfile, "vShader1", NULL);    
    cgGLLoadProgram(vShader);   // load vertex shader
   
    positionParam = cgGetNamedParameter(vShader, "position");
    cgGLEnableProfile(vProfile);
    cgGLBindProgram(vShader);
    
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(400, 300);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("My Cg Shader");
    init();
    glutDisplayFunc(display);
    glutMainLoop();
    
    // Release shaders once main drawing loop has stopped running
    cgDestroyProgram(vShader);
    cgDestroyContext(cgContext);

    return 0;
}

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