sjgui documentation

Lesson 3

In this lesson you will learn how to create animation in your window. We will modify code from the Lesson 2, to add animation to the triangle.

See also:

sjgui::CWnd::OnAnimate()

// For this lesson, you will learn how to make animation,
// we will animate the triangle from lesson2. Triangle will be
// rotating around Y axis. For that we have a special event OnAnimate().
class CSpcWnd : public sjgui::CWnd
{
    // This variable will hold the current rotation angle
    float   m_fRotation;
public:
    // Now we need a constructor, because m_fRotation should be reset
    // when class is initialized. We also should not forget to call
    // base class constructor
    CSpcWnd():CWnd(){m_fRotation=0.0f;}
    // New handler for animation
    virtual void OnAnimate()
    {
        // change rotation by 1 degree
        m_fRotation+=1;
        // we do not want to have rotation angle more then 360 degrees
        if(m_fRotation>360)m_fRotation-=360;
    }
    // Drawing is as it was in lesson2, we just need to add command for animations.
    virtual void OnDraw()
    {
        // For simplicity let's us call Animation function, when
        // we draw the scene, even though in a big program, it could
        // happen that you would like to animate everything in a separate thread.
        Animate();
        SET_GL_SIMPLE_PROSPECTIVE; // The same as it was in lesson2
        glTranslatef(0.0f,0.0f,-10.0f); // Move triangle down
        // Now we rotate our triangle around Y axis
        glRotatef(m_fRotation,0.0f,1.0f,0.0f);
        // Let us set color to a blue
        glColor3f(0.0f,0.0f,1.0f);
        // this is our triangle in the center of the screen.
        glBegin(GL_TRIANGLES);
            glVertex3f( 0.0f, 1.0f, 0.0f);
            glVertex3f(-1.0f,-1.0f, 0.0f);
            glVertex3f( 1.0f,-1.0f, 0.0f);
        glEnd();
    }
}; // end of CSpcWnd class

Back to Lesson 2. Forward to Lesson 4.

The following is full source code for this lesson.

// This header includes all resources of the sjgui library
#include <sjgui/sjgui.h>

// For this lesson, you will learn how to make animation,
// we will animate the triangle from lesson2. Triangle will be
// rotating around Y axis. For that we have a special event OnAnimate().
class CSpcWnd : public sjgui::CWnd
{
    // This variable will hold the current rotation angle
    float   m_fRotation;
public:
    // Now we need a constructor, because m_fRotation should be reset
    // when class is initialized. We also should not forget to call
    // base class constructor
    CSpcWnd():CWnd(){m_fRotation=0.0f;}
    // New handler for animation
    virtual void OnAnimate()
    {
        // change rotation by 1 degree
        m_fRotation+=1;
        // we do not want to have rotation angle more then 360 degrees
        if(m_fRotation>360)m_fRotation-=360;
    }
    // Drawing is as it was in lesson2, we just need to add command for animations.
    virtual void OnDraw()
    {
        // For simplicity let's us call Animation function, when
        // we draw the scene, even though in a big program, it could
        // happen that you would like to animate everything in a separate thread.
        Animate();
        SET_GL_SIMPLE_PROSPECTIVE; // The same as it was in lesson2
        glTranslatef(0.0f,0.0f,-10.0f); // Move triangle down
        // Now we rotate our triangle around Y axis
        glRotatef(m_fRotation,0.0f,1.0f,0.0f);
        // Let us set color to a blue
        glColor3f(0.0f,0.0f,1.0f);
        // this is our triangle in the center of the screen.
        glBegin(GL_TRIANGLES);
            glVertex3f( 0.0f, 1.0f, 0.0f);
            glVertex3f(-1.0f,-1.0f, 0.0f);
            glVertex3f( 1.0f,-1.0f, 0.0f);
        glEnd();
    }
}; // end of CSpcWnd class

// Now we need to setup our window, we do it in the function main.
int main(int argc, char* argv[])
{
    // Events receiver
    CSpcWnd SpcWnd;
    // Position the window
    SpcWnd.PosWnd(20,50,320,240);
    // Create window
    if(sjgui::Create("Animating",&SpcWnd))
    {
        // Run it. Now all events are transferred to our class.
        sjgui::GlobalMainLoop();
    }
    else
        // Print error message if something was wrong.
        printf("Could not create opengl window.\n");
    return 0;
} // the end of main