glutPassiveMotionFunc和glutWarpMousePointer

我想在OpenGL/GLUT窗口中实现自己的光标.通常的做法是冻结光标(因此无法触及屏幕边缘)并自行跟踪其位置.我可以使用屏幕上的光标隐藏

glutSetCursor(GLUT_CURSOR_NONE);

然后在我的glutPassiveMotionFunc回调内部使用指针移动指向窗口的中间位置

int centerX = (float)kWindowWidth / 2.0;
int centerY = (float)kWindowHeight / 2.0;

int deltaX = (x - centerX);
int deltaY = (y - centerY);

mouseX += deltaX / (float)kWindowWidth;
mouseY -= deltaY / (float)kWindowHeight;

glutWarpPointer( centerX, centerY );

这样可以保持指针卡在窗口中间.问题是,当我绘制'OpenGL'鼠标(在glutDisplayFunc()回调内部)时,它非常生涩.

我在网上看了一下,发现可能存在一个问题,即glutWarpPointer()导致再次调用glutPassiveMotionFunc回调,导致循环,但这似乎不会发生在这里.

我在Mac OS X上发现了一篇帖子,说CGDisplayMoveCursorToPoint更适合这个.调用CGDisplayMoveCursorToPoint可以工作,但运动仍然非常不稳定(我似乎得到很多事件,其中x和y都是0).在任何情况下,我都希望这能在Linux上运行,因此只有Mac的解决方案并不理想(但我不得不在不同的系统上做不同的事情).

我已将其缩减为测试用例.

#include 
#include 
#include 

int curX = 0;
int curY = 0;

void display() {
    glClearColor( 0.0, 0.0, 0.0, 1.0 );
    glClear( GL_COLOR_BUFFER_BIT );

    float vx = (float)curX / 300.0 + 0.5;
    float vy = (float)curY / 300.0 + 0.5;

    glColor3f( 1.0, 0.0, 0.0 );
    glBegin( GL_POINTS );
        glVertex3f( vx, vy, 0.0 );
    glEnd();

    glutSwapBuffers();

}

void passivemotion( int x, int y ) {
    int centerX = 150;
    int centerY = 150;

    int deltaX = x - centerX;
    int deltaY = y - centerY;
    curX += deltaX;
    curY -= deltaY;

    glutWarpPointer( centerX, centerY );
}

void timer( int val ) {
    glutTimerFunc( 16, &timer,  0);
    glutPostRedisplay();
}

int main (int argc, char * argv[]) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_RGB);
    glutInitWindowSize(300,300);
    glutCreateWindow("FPS Mouse Sample");
    glutDisplayFunc(&display);
    glutPassiveMotionFunc(&passivemotion);
    glutSetCursor( GLUT_CURSOR_NONE );
    glutTimerFunc( 16, &timer, 0 );
    glutMainLoop();
    return 0;
}

Steven Canfi.. 6

感谢aib的提示.你让我看着glutWarpPointer的反汇编,很明显发生了什么.调用glutWarpPointer CGPostMouseEvent导致一堆无意义的事件(并且没有任何方法可以跳过它们,因为每帧只获得一次鼠标事件,新的"真实"事件将会延迟).我发现的解决方案是只在指针位于屏幕边缘时才会扭曲(毕竟,点是假装点永远不会到达屏幕边缘).无论如何,这是代码.

int lastX = 150;
int lastY = 150;
void passivemotion( int x, int y ) {    
    int deltaX = x - lastX;
    int deltaY = y - lastY;

    lastX = x;
    lastY = y;

    if( deltaX == 0 && deltaY == 0 ) return;

    int windowX     = glutGet( GLUT_WINDOW_X );
    int windowY     = glutGet( GLUT_WINDOW_Y );
    int screenWidth     = glutGet( GLUT_SCREEN_WIDTH );
    int screenHeight    = glutGet( GLUT_SCREEN_HEIGHT );

    int screenLeft = -windowX;
    int screenTop = -windowY;
    int screenRight = screenWidth - windowX;
    int screenBottom = screenHeight - windowY;

    if( x <= screenLeft+10 || (y) <= screenTop+10 || x >= screenRight-10 || y >= screenBottom - 10) {
        lastX = 150;
        lastY = 150;
        glutWarpPointer( lastX, lastY );
        //  If on Mac OS X, the following will also work (and CGwarpMouseCursorPosition seems faster than glutWarpPointer).
        //  CGPoint centerPos = CGPointMake( windowX + lastX, windowY + lastY );
        //  CGWarpMouseCursorPosition( centerPos );
        // Have to re-hide if the user touched any UI element with the invisible pointer, like the Dock.
        //  CGDisplayHideCursor(kCGDirectMainDisplay);
    }

    curX += deltaX;
    curY -= deltaY;
}

Nathan S... 5

我找到了一个更好的方法.发生了什么事情,操作系统在扭曲鼠标后抑制事件约0.25秒.所以,只需要打电话:

#ifdef __APPLE__
CGSetLocalEventsSuppressionInterval(0.0);
#endif

然后一切都会顺利而没有任何口吃.

您可能需要包括:

#include 

并将此框架添加到您的项目或编译器选项中.

请注意,您可能会收到鼠标移动到屏幕中心的事件,因此如果它位于屏幕中间,我只会忽略该事件.

感谢aib的提示.你让我看着glutWarpPointer的反汇编,很明显发生了什么.调用glutWarpPointer CGPostMouseEvent导致一堆无意义的事件(并且没有任何方法可以跳过它们,因为每帧只获得一次鼠标事件,新的"真实"事件将会延迟).我发现的解决方案是只在指针位于屏幕边缘时才会扭曲(毕竟,点是假装点永远不会到达屏幕边缘).无论如何,这是代码.

int lastX = 150;
int lastY = 150;
void passivemotion( int x, int y ) {    
    int deltaX = x - lastX;
    int deltaY = y - lastY;

    lastX = x;
    lastY = y;

    if( deltaX == 0 && deltaY == 0 ) return;

    int windowX     = glutGet( GLUT_WINDOW_X );
    int windowY     = glutGet( GLUT_WINDOW_Y );
    int screenWidth     = glutGet( GLUT_SCREEN_WIDTH );
    int screenHeight    = glutGet( GLUT_SCREEN_HEIGHT );

    int screenLeft = -windowX;
    int screenTop = -windowY;
    int screenRight = screenWidth - windowX;
    int screenBottom = screenHeight - windowY;

    if( x <= screenLeft+10 || (y) <= screenTop+10 || x >= screenRight-10 || y >= screenBottom - 10) {
        lastX = 150;
        lastY = 150;
        glutWarpPointer( lastX, lastY );
        //  If on Mac OS X, the following will also work (and CGwarpMouseCursorPosition seems faster than glutWarpPointer).
        //  CGPoint centerPos = CGPointMake( windowX + lastX, windowY + lastY );
        //  CGWarpMouseCursorPosition( centerPos );
        // Have to re-hide if the user touched any UI element with the invisible pointer, like the Dock.
        //  CGDisplayHideCursor(kCGDirectMainDisplay);
    }

    curX += deltaX;
    curY -= deltaY;
}

我找到了一个更好的方法.发生了什么事情,操作系统在扭曲鼠标后抑制事件约0.25秒.所以,只需要打电话:

#ifdef __APPLE__
CGSetLocalEventsSuppressionInterval(0.0);
#endif

然后一切都会顺利而没有任何口吃.

您可能需要包括:

#include 

并将此框架添加到您的项目或编译器选项中.

请注意,您可能会收到鼠标移动到屏幕中心的事件,因此如果它位于屏幕中间,我只会忽略该事件.