CODEWITHSUNDEEP
c++openglrotationscene
AvidScifiReader
AvidScifiReader

Reputation: 279

Rotating around world 0,0,0 instead of object center

My object is rotating around 0,0,0, but I want it to rotate around itself on the Y-Axis. I know there are other cases

Rotating object around itself in OpenGL

glRotatef not rotating as expected

but I don't have any translations before the rotation an still it doesn't work.

My EDITED Code:

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

glRotatef(_angle,0.0f,1.0f,0.0f);
glPushMatrix();

glTranslatef(0.0f,0.0f,-6.0f);
glBegin(GL_TRIANGLES);
    //Front
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);

    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);

    //Back
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);

    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);

    //Right
    glVertex3f(1.0f, 1.0f, 1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);

    glVertex3f(1.0f, 1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);


    //Left
    glVertex3f(-1.0f, 1.0f, 1.0f);
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);

    glVertex3f(-1.0f, 1.0f, 1.0f);
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);


    //Top
    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(-1.0f, 1.0f, 1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);

    glVertex3f(-1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, -1.0f);
    glVertex3f(1.0f, 1.0f, 1.0f);


    //Bottom
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, 1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);

    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, -1.0f);
    glVertex3f(1.0f, -1.0f, 1.0f);
glEnd();
glPopMatrix();

glutSwapBuffers();

My Original Code:

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

glRotatef(angle,0.0f,1.0f,0.0f);  //The angle is a float that slowly increases until it reaches 360 Degrees, and then resets to 0.0
    /* This is a Cube */
glBegin(GL_TRIANGLES);
    //Front
    glVertex3f(-1.0f, -1.0f, -5.0f);
    glVertex3f(-1.0f, 1.0f, -5.0f);
    glVertex3f(1.0f, 1.0f, -5.0f);

    glVertex3f(-1.0f, -1.0f, -5.0f);
    glVertex3f(1.0f, -1.0f, -5.0f);
    glVertex3f(1.0f, 1.0f, -5.0f);

    //Back
    glVertex3f(-1.0f, -1.0f, -7.0f);
    glVertex3f(-1.0f, 1.0f, -7.0f);
    glVertex3f(1.0f, 1.0f, -7.0f);

    glVertex3f(-1.0f, -1.0f, -7.0f);
    glVertex3f(1.0f, -1.0f, -7.0f);
    glVertex3f(1.0f, 1.0f, -7.0f);

    //Right
    glVertex3f(1.0f, 1.0f, -5.0f);
    glVertex3f(1.0f, -1.0f, -5.0f);
    glVertex3f(1.0f, -1.0f, -7.0f);

    glVertex3f(1.0f, 1.0f, -5.0f);
    glVertex3f(1.0f, 1.0f, -7.0f);
    glVertex3f(1.0f, -1.0f, -5.0f);


    //Left
    glVertex3f(-1.0f, 1.0f, -5.0f);
    glVertex3f(-1.0f, -1.0f, -5.0f);
    glVertex3f(-1.0f, -1.0f, -7.0f);

    glVertex3f(-1.0f, 1.0f, -5.0f);
    glVertex3f(-1.0f, 1.0f, -7.0f);
    glVertex3f(-1.0f, -1.0f, -7.0f);


    //Top
    glVertex3f(-1.0f, 1.0f, -7.0f);
    glVertex3f(-1.0f, 1.0f, -5.0f);
    glVertex3f(1.0f, 1.0f, -5.0f);

    glVertex3f(-1.0f, 1.0f, -7.0f);
    glVertex3f(1.0f, 1.0f, -7.0f);
    glVertex3f(1.0f, 1.0f, -5.0f);


    //Bottom
    glVertex3f(-1.0f, -1.0f, -7.0f);
    glVertex3f(-1.0f, -1.0f, -5.0f);
    glVertex3f(1.0f, -1.0f, -5.0f);

    glVertex3f(-1.0f, -1.0f, -7.0f);
    glVertex3f(1.0f, -1.0f, -7.0f);
    glVertex3f(1.0f, -1.0f, -5.0f);
glEnd();

glutSwapBuffers();

Upvotes: 1

Views: 400

Answers (1)

genpfault
genpfault

Reputation: 52155

Make sure the center of your object is at the origin of its local coordinate system.

For your cube your X/Y seem centered but your Z center looks to be at -6.

Upvotes: 2

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