Transformations

OpenGL OpenGL: Basic Coding
1

How to rotate the object itself? And when i scale the object the position of the object also moved; I want to place the object at same positio.

2

glRotate… is used to rotate.

An object is scaled around the origin so if you for example center a cube around the origin and then scale it, it will not move.

It is important to do scaling/rotation/translation in correct order.

Mikael

[This message has been edited by mikael_aronsson (edited 11-03-2003).]

3

Can you give the code, Please.

4

Hi,

Try some simple opengl examples here… http://myopendemo.hypermart.net

5

Here i have placed my code. I tried to rotate the object around itself. But it won’t work. Please modify the code.

glLoadIdentity();
glRotatef(gfAngle, 0.0f, 0.0f, 10.0f);

glBegin(GL_LINE_LOOP);
	glVertex3f(10.0f, 10.0f, 0.0f);
	glVertex3f(60.0f, 10.0f, 0.0f);
	glVertex3f(60.0f, 60.0f, 0.0f);
	glVertex3f(10.0f, 60.0f, 0.0f);
	glVertex3f(10.0f, 10.0f, 0.0f);
glEnd();

glLoadIdentity();

glFinish();

[This message has been edited by Balu (edited 11-03-2003).]

6

Ok, if my calculations are right, the center of that line loop is about 35,35.

So… do this:

glTranslatef(35, 35, 0); // translate back to position
glRotatef(gfAngle, 0.0f, 0.0f, 1.0f);
glTranslatef(-35, -35, 0); // translate to origin

7

Thank you, it is very helpful for me.