OpenGL Spotlights - c++

Question

I'm trying to make 'spotlights' over a pool table in openGL. This should be fairly simple, but something is going wrong, and I can't work out what.
I have a class 'PoolLight' that I'm using as a sort of holding class for the lights. Here is is:
#include "PoolLight.h"
#include "Glut/glut.h"
#include "GL/gl.h"
#include "GL/glu.h"
PoolLight::PoolLight() {
}
PoolLight::PoolLight(GLenum lightNumber, GLenum lightType, float red, float green, float blue, bool distant, float posX, float posY, float posZ)
{
this->lightNumber = lightNumber;
this->lightType = lightType;
color[0] = red; color[1] = green; color[2] = blue; color[3] = 1;
position[0] = posX; position[1] = posY; position[2] = posZ; position[3] = (int) (!distant);
glLightfv(lightNumber, lightType, color);
glLightfv(lightNumber, GL_POSITION, position);
enabled(true);
}
PoolLight::~PoolLight(void)
{
}
void PoolLight::setSpotlight(float angle, float attenuation, float dirX, float dirY, float dirZ) {
glLightf(lightNumber, GL_SPOT_EXPONENT, angle);
glLightf(lightNumber, GL_CONSTANT_ATTENUATION, attenuation);
glLightf(lightNumber, GL_LINEAR_ATTENUATION, 0.0f);
glLightf(lightNumber, GL_QUADRATIC_ATTENUATION, 0.0f);
spotDirection[0] = dirX; spotDirection[1] = dirY; spotDirection[2] = dirZ;
glLightfv(lightNumber, GL_SPOT_DIRECTION, spotDirection);
glLightf(lightNumber, GL_SPOT_CUTOFF, 60);
}
void PoolLight::enabled(bool enabled) {
if (enabled) glEnable(lightNumber);
else glDisable(lightNumber);
}
void PoolLight::reposition() {
glLightfv(lightNumber, GL_POSITION, position);
}
And in Display::Init, I have this code:
glEnable(GL_TEXTURE_2D);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glPointSize(6);
//Lighting
middleSpotlight = PoolLight(GL_LIGHT0, GL_DIFFUSE, .3, .3, 0.15, false, 0, 0, 50);
middleSpotlight.setSpotlight(60, 1, 0, 0, -1);
upperSpotlight = PoolLight(GL_LIGHT1, GL_DIFFUSE, .3, .3, 0.15, false, 0, 45, 50);
upperSpotlight.setSpotlight(60, 1, 0, 0, -1);
lowerSpotlight = PoolLight(GL_LIGHT2, GL_DIFFUSE, .3, .3, 0.15, false, 0, -45, 50);
lowerSpotlight.setSpotlight(60, 1, 0, 0, -1);
However, even when disabling all but the middle spotlight my scene is uniformly lit with a sort of 'blanket' lighting.
I feel like I'm probably missing something obvious, but I just can't see what.

Answer 1

This is due to how OpenGL default fixed function pipeline implements lighting: Lighting is evaluated only at the vertices, the resulting colour interpolated over the surface. If your whole table consists of just one large quad, exactly this happens.
Solution 1: Subdivide the mesh to a high degree.
Solution 2: Replace fixed function lighting with a per-fragment-illumination shader.