World transform (like DX) in OpenGL?

[cronodragon]

Does OGL has a World transform matrix like DirectX? :D

Regards!
-Marco

[Dan]

OpenGL matrices are a bit different from DirectX ones.
DX has 3 matrices in total that affect geometry transformations - World, View, Projection.
OGL has only 2 - ModelView, Projection. ModelView is basically a combinations of World and View matrices.

So to answer your question, OpenGL has a transform similar the Direct3D, but not exactly the same.

[cronodragon]

Hmm, how can I create a world transform + view transform matrix for OGL?

[Dan]

glMatrixMode(GL_MODELVIEW);
glLoadIdentity;
gluLookAt(EyeX, EyeY, EyeZ, TargetX, TargetY, TargetZ, UpX, UpY, UpZ);
//this creates the view matrix transformation

then you can use
glRotatef, glScalef, glTranslatef to build the world matrix

or you can use glLoadMatrixf to load already built World*View matrix.

[cronodragon]

So basically I just multiply World*View?

Regards!
-Marco

[Dan]

yes and then pass it to OGL with glLoadMatrixf