1D Texture lookup table with fixed function pipeline - c++

Question

I want to create a 1D texture with OpenGL's (old) fixed function pipeline, which interpolated through three colors.
After looking online: glTexImage1D is commonly referred to. I cannot find any good simple sample codes for this, and I wouldn't know how to return a (RGB) value from this.
Does OpenGL (fixed function) have any methods for creating a 1D Texture, and returning an RGB value from this?

Answer 1

Yup, glTexImage1D() + GL_TEXTURE_1D:
#include <GL/glew.h>
#include <GL/glut.h>
GLuint tex = 0;
void display()
{
glClear( GL_COLOR_BUFFER_BIT );
glEnable( GL_TEXTURE_1D );
glBindTexture( GL_TEXTURE_1D, tex );
glBegin(GL_TRIANGLES);
glTexCoord1f( 0.0f );
glVertex2f( -0.5f, -0.5f );
glTexCoord1f( 0.5f );
glVertex2f( 0.5f, -0.5f );
glTexCoord1f( 1.0f );
glVertex2f( 0.0f, 0.5f );
glEnd();
glutSwapBuffers();
}
int main( int argc, char** argv )
{
glutInit( &argc, argv );
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE );
glutInitWindowSize( 400, 400 );
glutCreateWindow( "GLUT" );
glewInit();
glGenTextures( 1, &tex );
glBindTexture( GL_TEXTURE_1D, tex );
unsigned char pixels[] =
{
255, 0, 0, 255,
0, 255, 0, 255,
0, 0, 255, 255,
};
glTexImage1D( GL_TEXTURE_1D, 0, GL_RGBA, 3, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels );
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL );
glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glutDisplayFunc( display );
glutMainLoop();
return 0;
}