# Cube map Texture Coordinates

I’m trying to render each side of a cube map onto a flat texture but I don’t know how cube map uv mapping works.

``````
//bind cube map texture

glTexCoord3f(1, 0, 0); glVertex2f(0, 0);
glTexCoord3f(1, 0, 0); glVertex2f(0, 1);
glTexCoord3f(1, 0, 0); glVertex2f(1, 1);
glTexCoord3f(1, 0, 0); glVertex2f(1, 0);
glEnd();

``````

I read somewhere that the coordinate is basically a normal, so that should be displaying one of the sides of the cubemap, except it isn’t. Any help would be appreciated.

If you want to visualize cube map as a 2D cross, then the following may be useful. The code doesn’t use immediate mode but you should be able to see texture coordinates and vertex positions:

``````float z = 10.0f;
float a = 128.0f;
Vector2 O = new Vector2(4.0f, 30.0f);
Vector2 A;
Vector2 B;
Vector2 C;
Vector2 D;

//       B    C
//        posy
//       A    D
// B    CB    CB    CB    C
//  negx  posz  posx  negz
// A    DA    DA    DA    D
//       B    C
//        negy
//       A    D

//  negx   rz -ry rx
A = O + new Vector2(0.0f, a);
B = A + new Vector2(0.0f, a);
C = A + new Vector2(a, a);
D = A + new Vector2(a, 0);
vertexBufferRange.CurrentIndex,      vertexBufferRange.CurrentIndex + 1,
vertexBufferRange.CurrentIndex + 2,  vertexBufferRange.CurrentIndex + 3
);
indexBufferRange.CurrentIndex += 6;
vertexBufferRange.Set(texcoord,  -1.0f, -1.0f,  -1.0f); vertexBufferRange.Set(position,  A.X,    A.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  -1.0f,  1.0f,  -1.0f); vertexBufferRange.Set(position,  B.X,    B.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  -1.0f,  1.0f,   1.0f); vertexBufferRange.Set(position,  C.X,    C.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  -1.0f, -1.0f,   1.0f); vertexBufferRange.Set(position,  D.X,    D.Y,    z);   ++vertexBufferRange.CurrentIndex;

//  posz   rx -ry rz
A = O + new Vector2(a, a);
B = A + new Vector2(0.0f, a);
C = A + new Vector2(a, a);
D = A + new Vector2(a, 0);
vertexBufferRange.CurrentIndex,      vertexBufferRange.CurrentIndex + 1,
vertexBufferRange.CurrentIndex + 2,  vertexBufferRange.CurrentIndex + 3
);
indexBufferRange.CurrentIndex += 6;
vertexBufferRange.Set(texcoord, -1.0f, -1.0f,   1.0f); vertexBufferRange.Set(position,  A.X,    A.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord, -1.0f,  1.0f,   1.0f); vertexBufferRange.Set(position,  B.X,    B.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,  1.0f,   1.0f); vertexBufferRange.Set(position,  C.X,    C.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f, -1.0f,   1.0f); vertexBufferRange.Set(position,  D.X,    D.Y,    z);   ++vertexBufferRange.CurrentIndex;

//  posy   rx  rz ry
A = O + new Vector2(a, 2.0f * a);
B = A + new Vector2(0.0f, a);
C = A + new Vector2(a, a);
D = A + new Vector2(a, 0);
vertexBufferRange.CurrentIndex,      vertexBufferRange.CurrentIndex + 1,
vertexBufferRange.CurrentIndex + 2,  vertexBufferRange.CurrentIndex + 3
);
indexBufferRange.CurrentIndex += 6;
vertexBufferRange.Set(texcoord, -1.0f,  1.0f,   1.0f); vertexBufferRange.Set(position,  A.X,    A.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord, -1.0f,  1.0f,  -1.0f); vertexBufferRange.Set(position,  B.X,    B.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,  1.0f,  -1.0f); vertexBufferRange.Set(position,  C.X,    C.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,  1.0f,   1.0f); vertexBufferRange.Set(position,  D.X,    D.Y,    z);   ++vertexBufferRange.CurrentIndex;

//  negy   rx -rz ry
A = O + new Vector2(a, 0.0f);
B = A + new Vector2(0.0f, a);
C = A + new Vector2(a, a);
D = A + new Vector2(a, 0);
vertexBufferRange.CurrentIndex,      vertexBufferRange.CurrentIndex + 1,
vertexBufferRange.CurrentIndex + 2,  vertexBufferRange.CurrentIndex + 3
);
indexBufferRange.CurrentIndex += 6;
vertexBufferRange.Set(texcoord, -1.0f,  -1.0f,  -1.0f); vertexBufferRange.Set(position,  A.X,    A.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord, -1.0f,  -1.0f,   1.0f); vertexBufferRange.Set(position,  B.X,    B.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,  -1.0f,   1.0f); vertexBufferRange.Set(position,  C.X,    C.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,  -1.0f,  -1.0f); vertexBufferRange.Set(position,  D.X,    D.Y,    z);   ++vertexBufferRange.CurrentIndex;

//  posx  -rz -ry rx
A = O + new Vector2(2.0f * a, a);
B = A + new Vector2(0.0f, a);
C = A + new Vector2(a, a);
D = A + new Vector2(a, 0);
vertexBufferRange.CurrentIndex,      vertexBufferRange.CurrentIndex + 1,
vertexBufferRange.CurrentIndex + 2,  vertexBufferRange.CurrentIndex + 3
);
indexBufferRange.CurrentIndex += 6;
vertexBufferRange.Set(texcoord,  1.0f,  -1.0f,   1.0f); vertexBufferRange.Set(position,  A.X,    A.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,   1.0f,   1.0f); vertexBufferRange.Set(position,  B.X,    B.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,   1.0f,  -1.0f); vertexBufferRange.Set(position,  C.X,    C.Y,    z);   ++vertexBufferRange.CurrentIndex;
vertexBufferRange.Set(texcoord,  1.0f,  -1.0f,  -1.0f); vertexBufferRange.Set(position,  D.X,    D.Y,    z);   ++vertexBufferRange.CurrentIndex;

//  negz  -rx -ry rz
A = O + new Vector2(3.0f * a, a);
B = A + new Vector2(0.0f, a);
C = A + new Vector2(a, a);
D = A + new Vector2(a, 0);