问题是鼠标点击距离左上角原点(0,0)越远,绘制顶点时的高度误差越大。有什么想法吗?
int WindowWidth = 19;
int WindowHeight = 13;
int mouseClickCount = 0;
int rectPlotted;
GLint x1;
GLint y1;
GLint x2;
GLint y2;
//Declare our functions with prototypes:
void display(void);
void init (void);
void processNormalKeys(unsigned char key, int x, int y);
void on_vertex_selected(GLint x, GLint y);
void on_mouse_event(int button, int state, int x, int y);
/////////////////////////////////// MAIN ////////////////////////////////
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
//start calculation of max window size available at 19:13 aspect ratio
int screenWidth = glutGet(GLUT_SCREEN_WIDTH);
int screenHeight = glutGet(GLUT_SCREEN_HEIGHT);
screenWidth = screenWidth/WindowWidth;
WindowWidth = WindowWidth*screenWidth;
screenHeight = screenHeight/WindowHeight;
WindowHeight = screenHeight*WindowHeight;
//end calculation
glutInitWindowSize (WindowWidth, WindowHeight);
glutInitWindowPosition (0, 0);
glutCreateWindow ("Plot a rectangle!");
glutDisplayFunc(display);
glutKeyboardFunc(processNormalKeys);
glutMouseFunc(on_mouse_event);
init();
glutMainLoop();
return 0;
}
/////////////////////////////////////////////////////////////////////////
void display(void)
{
glClear (GL_COLOR_BUFFER_BIT); //clear all pixels
glFlush();
}
void init (void)
{
/* select clearing (background) color */
glClearColor (1.0, 1.0, 1.0, 0.0);
/* initialize viewing values */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, WindowWidth, 0, WindowHeight, -1.0, 1.0);
}
void processNormalKeys(unsigned char key, int x, int y) {
if (key == 27) //esc
exit(0);
//Allows color change of most recently plotted rectangle
if (key == 98){ //b
glColor3f(0.0, 0.0, 1.0);
glBegin(GL_QUADS);
glVertex2i(x1, y1);
glVertex2i(x1, y2);
glVertex2i(x2, y2);
glVertex2i(x2, y1);
glEnd();
glFlush();
}
if (key == 114){ //r
glColor3f(1.0, 0.0, 0.0);
glBegin(GL_QUADS);
glVertex2i(x1, y1);
glVertex2i(x1, y2);
glVertex2i(x2, y2);
glVertex2i(x2, y1);
glEnd();
glFlush();
}
if (key == 103){ //g
glColor3f(0.0, 1.0, 0.0);
glBegin(GL_QUADS);
glVertex2i(x1, y1);
glVertex2i(x1, y2);
glVertex2i(x2, y2);
glVertex2i(x2, y1);
glEnd();
glFlush();
}
}
void on_vertex_selected(GLint x, GLint y){
if(mouseClickCount == 0){
x1 = x;
y1 = y;
glColor3f(0.0, 0.0, 0.0);
glEnable(GL_POINT_SMOOTH);
glPointSize(5.0);
glBegin(GL_POINTS);
glVertex2i(x1, y1);
glEnd();
glFlush();
}
else{
x2 = x;
y2 = y;
glBegin(GL_POINTS);
glColor3f(1.0, 1.0, 1.0);
glVertex2i(x1,y1); //"clears" previous point to make way for the rectangle
glEnd();
glColor3f(0.0, 0.0, 0.0);
glBegin(GL_QUADS);
glVertex2i(x1, y1);
glVertex2i(x1, y2);
glVertex2i(x2, y2);
glVertex2i(x2, y1);
glEnd();
glFlush();
}
}
void on_mouse_event(int button, int state, int x, int y){
if(button==GLUT_LEFT_BUTTON && state ==GLUT_DOWN && mouseClickCount == 0){
//y = y+20; //adjusts for VM mouse tracking error
on_vertex_selected(x, WindowHeight - y);
rectPlotted = 0;
}
if(button==GLUT_LEFT_BUTTON && state ==GLUT_UP && mouseClickCount == 0){
if(rectPlotted == 1){
return;
}
else{
mouseClickCount++;
}
}
if(button==GLUT_LEFT_BUTTON && state ==GLUT_DOWN && mouseClickCount == 1){
//y = y+20; //adjusts for VM mouse tracking error
on_vertex_selected(x, WindowHeight - y);
mouseClickCount = 0;
rectPlotted = 1;
}
}
答案 0 :(得分:1)
你的glOrtho()电话几乎肯定是错的。您传递窗口大小,而不是窗口客户区大小。区别在于边框的大小和标题的高度。
答案 1 :(得分:0)
请注意,您的实际窗口大小可能与您在初始时询问的内容略有不同。
简单地说,实施一个glutReshapeFunc()
答案 2 :(得分:0)
我正在Parallels VM v.6中编译和运行我的代码。这是导致返回不准确的鼠标坐标的问题。我在OS X上编译并运行完全相同的代码没有问题。