Mouse Trail in OpenGL

This is a discussion on Mouse Trail in OpenGL within the Game Programming forums, part of the General Programming Boards category; Hi, I am trying to bind an object to the PassiveMouseFunc now I can get it to draw the shape. ...

  1. #1
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    Mouse Trail in OpenGL

    Hi,

    I am trying to bind an object to the PassiveMouseFunc

    now I can get it to draw the shape. however when i move the mouse it creates a trail, I don't want a trail.

    I am already using double buffering, is there a way to get rid of the trail?

    This is what i am talking about

    Thx
    -Ti22-

  2. #2
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    The first thing to do in your drawing function is this:
    Code:
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
    // Do al the drawing and stuff

  3. #3
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    OK I did it, I put the thing in my passiveMotion callback but when i do this everything else (the flowers i draw appear for a sec and disappears.
    Last edited by Ti22; 11-07-2004 at 12:23 PM.
    -Ti22-

  4. #4
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    You need to call your drawing function every frame you want it to be drawn. If your doing that I dont know why it dissappears, then I need to see code.

  5. #5
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    Code:
    void mouseMotion (GLint x, GLint y)
    {
    	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    	waterThingy(x-400, (-y)+250, 0.0, 1.0, 1.0, 1.0);
    	glutSwapBuffers();
    }
    
    void mainDisplay (GLvoid)
    {
    	glMatrixMode(GL_MODELVIEW);
    	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    	
    	glLoadIdentity();
    	world();
    	glLoadIdentity();
    	flower(500.0, 500.0, 0.0, 0.2, 0.2, 0.2);
    	glLoadIdentity();
    	flower(1000.0, 500.0, 0.0, 0.2, 0.2, 0.2);
    	glLoadIdentity();
    	drawBucket(1500.0, 500.0, 0.0, 0.2, 0.2, 0.2);
    	glLoadIdentity();
    	flower(100.0, 0.0, 0.0, 1.0, 1.0, 1.0);
    	glLoadIdentity();
    	drawBucket(-300, 0.0, 0.0, 1.0, 1.0, 1.0);
    	glLoadIdentity();
    	flower(300.0, 0.0, 0.0, 1.0, 1.0, 1.0);
    	
    	glutSwapBuffers();
    			
    }
    
    void main(int argc, char **argv)
    {
    	glutInit(&argc, argv);
    	
    	glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGB);
    	glutInitWindowSize(800, 600);
    	glutCreateWindow("Flower and Pot");
    	InitGL();
    	glutReshapeFunc(resize);
    	glutDisplayFunc(mainDisplay);
    	glutKeyboardFunc(keyBoard);
    	glutPassiveMotionFunc(mouseMotion);
    	
    	glutMainLoop();
    }
    I am using the line u gave me in the passivemotionfunc callback.
    -Ti22-

  6. #6
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    Code:
    void mouseMotion (GLint x, GLint y)
    {
    	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Get rid of this here
    	waterThingy(x-400, (-y)+250, 0.0, 1.0, 1.0, 1.0);
    	glutSwapBuffers(); // Get rid of this too
    }
    You should only clear the buffer once every frame, and only swap it once every frame. Also check out the FAQ or search the board why void main is bad.
    Last edited by Shakti; 11-07-2004 at 12:40 PM.

  7. #7
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    if i get rid of those lines it the object i bind to the mouse won't show up. and I changed it to int main.

    btw shakti(means power in hindi rite?), i really appreciate this. ur replying so fast.
    Last edited by Ti22; 11-07-2004 at 12:47 PM.
    -Ti22-

  8. #8
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    Ok do this instead, have two global variables that should be the place where you want to draw the waterthingy, then in your mainDisplay you draw that with those coordinates instead, something like
    Code:
    GLint waterX = 0;
    GLint waterY = 0;
    void mouseMotion (GLint x, GLint y)
    {
            waterX = x-400;
            waterY = (-y)+250;
    }
    
    void mainDisplay (GLvoid)
    {
    	glMatrixMode(GL_MODELVIEW);
    	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    	
    	glLoadIdentity();
    	world();
    	glLoadIdentity();
    	flower(500.0, 500.0, 0.0, 0.2, 0.2, 0.2);
    	glLoadIdentity();
    	flower(1000.0, 500.0, 0.0, 0.2, 0.2, 0.2);
    	glLoadIdentity();
    	drawBucket(1500.0, 500.0, 0.0, 0.2, 0.2, 0.2);
    	glLoadIdentity();
    	flower(100.0, 0.0, 0.0, 1.0, 1.0, 1.0);
    	glLoadIdentity();
    	drawBucket(-300, 0.0, 0.0, 1.0, 1.0, 1.0);
    	glLoadIdentity();
    	flower(300.0, 0.0, 0.0, 1.0, 1.0, 1.0);
    
    	waterThingy(waterX,waterY, 0.0, 1.0, 1.0, 1.0);
    	
    	glutSwapBuffers();
    			
    }
    Try something along those lines. if waterThingy actaully draws something (as I suspect it does) you really really want it to be in the drawing function.

  9. #9
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    ok i did that but now the Watering Can gets fixed it one position it doesn't move with the mouse.

    Don't I have to return waterX and waterY to Global Variable ?
    Last edited by Ti22; 11-07-2004 at 12:59 PM.
    -Ti22-

  10. #10
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    Code:
    void mouseMotion (GLint x, GLint y)
    {
            waterX = x-400;
            waterY = (-y)+250;
            glutPostRedisplay();
    }

  11. #11
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    WOW its Works !!! thx alot guys, really appreciate this.

    Hugs and Kisses
    Last edited by Ti22; 11-07-2004 at 01:02 PM.
    -Ti22-

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