3D OpenGL Cube
Post: #1
I'm trying to generate a 3D OpenGL Cube... I looked at the BoingX example, and that is a sphere... how might I change that to be a simple cube?
I understand all the vertex stuff, I make 4, but there isn't any mesh around it...
theirs looks like:
I understand all the vertex stuff, I make 4, but there isn't any mesh around it...
theirs looks like:
Code:
int x;
int index = 0;
float v1x, v1y, v1z;
float v2x, v2y, v2z;
float d;
int theta, phi;
float theta0, theta1;
float phi0, phi1;
Vertex vtx[4];
float delta = M_PI / 8.0f;
// 8 vertical segments
for(theta = 0; theta < 8; theta++)
{
theta0 = theta*delta;
theta1 = (theta+1)*delta;
// 16 horizontal segments
for(phi = 0; phi < 16; phi++)
{
phi0 = phi*delta;
phi1 = (phi+1)*delta;
// For now, generate 4 full points.
vtx[0].x = r * sin(theta0)*cos(phi0);
vtx[0].y = r * cos(theta0);
vtx[0].z = r * sin(theta0)*sin(phi0);
vtx[1].x = r * sin(theta0)*cos(phi1);
vtx[1].y = r * cos(theta0);
vtx[1].z = r * sin(theta0)*sin(phi1);
vtx[2].x = r * sin(theta1)*cos(phi1);
vtx[2].y = r * cos(theta1);
vtx[2].z = r * sin(theta1)*sin(phi1);
vtx[3].x = r * sin(theta1)*cos(phi0);
vtx[3].y = r * cos(theta1);
vtx[3].z = r * sin(theta1)*sin(phi0);
// Generate normal
if(theta >= 4)
{
v1x = vtx[1].x - vtx[0].x;
v1y = vtx[1].y - vtx[0].y;
v1z = vtx[1].z - vtx[0].z;
v2x = vtx[3].x - vtx[0].x;
v2y = vtx[3].y - vtx[0].y;
v2z = vtx[3].z - vtx[0].z;
}
else
{
v1x = vtx[0].x - vtx[3].x;
v1y = vtx[0].y - vtx[3].y;
v1z = vtx[0].z - vtx[3].z;
v2x = vtx[2].x - vtx[3].x;
v2y = vtx[2].y - vtx[3].y;
v2z = vtx[2].z - vtx[3].z;
}
vtx[0].nx = (v1y * v2z) - (v2y * v1z);
vtx[0].ny = (v1z * v2x) - (v2z * v1x);
vtx[0].nz = (v1x * v2y) - (v2x * v1y);
d = 1.0f/sqrt(vtx[0].nx*vtx[0].nx +
vtx[0].ny*vtx[0].ny +
vtx[0].nz*vtx[0].nz);
vtx[0].nx *= d;
vtx[0].ny *= d;
vtx[0].nz *= d;
// Generate color
if((theta ^ phi) & 1)
{
vtx[0].r = 1.0f;
vtx[0].g = 1.0f;
vtx[0].b = 1.0f;
vtx[0].a = 1.0f;
}
else
{
vtx[0].r = 1.0f;
vtx[0].g = 0.0f;
vtx[0].b = 0.0f;
vtx[0].a = 1.0f;
}
// Replicate vertex info
for(x = 0; x < 4; x++)
{
vtx[x].nx = vtx[0].nx;
vtx[x].ny = vtx[0].ny;
vtx[x].nz = vtx[0].nz;
vtx[x].r = vtx[0].r;
vtx[x].g = vtx[0].g;
vtx[x].b = vtx[0].b;
vtx[x].a = vtx[0].a;
}
// Store vertices
boingData[index++] = vtx[0];
boingData[index++] = vtx[1];
boingData[index++] = vtx[2];
boingData[index++] = vtx[3];
Post: #3
The code you have posted looks like a sphere is going to be rendered not a cube. As OSC said look into nehe tutorials on it. Cubes aren't hard but require you to think in 3D. You will have 6 sides. So you will need 24 glVertex3f() calls. To descirbe your cube. HTH
Possibly Related Threads...
| Thread: | Author | Replies: | Views: | Last Post | |
| Cube auto-rotate | sakrist | 2 | 2,646 |
May 5, 2009 03:31 AM Last Post: Ingemar |
|
| OpenGL ES - Drawing a simple cube help. | MattCairns | 7 | 11,125 |
Oct 10, 2008 05:26 PM Last Post: Frogblast |
|
| Pre-generated cube map | Fenris | 2 | 3,244 |
Apr 5, 2007 07:01 PM Last Post: nich |
|
| Transformation from unit cube to view frustum | TomorrowPlusX | 10 | 5,407 |
Jul 12, 2005 11:32 AM Last Post: TomorrowPlusX |
|
| Cube Environment | PowerMacX | 3 | 2,745 |
Aug 7, 2003 09:36 PM Last Post: MattDiamond |
|