openGL ES Rotation about a point

I'm attempting to get an object to rotate about the origin point (0,0,0)

I'm following some gu开发者_如何学JAVAidelines from this blog and was able to get the basic rotation about the Z axis and it makes a very tight circle about the Z azis.

When I change it to the X or Y axis the triangle I made goes behind me and then shows up from the other side.

The basic effect I'm hoping to achieve is to have it spin right infront of the camera.

I understand that I would have to rotate it by the amount I want and then translate it back to the origin, but I'm not quite sure on how to figure out how much to translate it by.

Can someone give me a push in the right direction about this especially the formula I would need to use to translate it properly?

Hard to answer without seeing your code, but it sounds like you want to first translate the center of the triangle to the origin, rotate, then translate back to the triangle's original position. glRotate() rotates around the origin, not an arbitrary point.

So, effectively,

glTranslatef(centerX, centerY, centerZ);
glRotatef(angle, 0, 0, 1);
glTranslatef(-centerX, -centerY, -centerZ);

Remember that OpenGL transformations are applied in reverse order that they are specified in the code, so the above translates by -(centerX, centerY, centerZ), then rotates, then translates back by (centerX, centerY, centerZ).

Check out Chapter 3 of the OpenGL Programming Guide for more information.