我在摆弄图形,并试图找到一种方法,使我绘制的形状(在本例中为三角形)与窗口大小成比例。但是,我只希望宽度更新,高度保持不变。
我已经做了一些研究,并尝试使用glutGet(GLUT_Screeen_WIDTH)作为我形状顶点的乘数或类似的东西(例如(GLUT·斯creen_WIDTH/100)-250),但我觉得我可能错过了一个关键的想法。我应该将缩放操作应用于视口,而不是应用于形状的点吗?每当我缩放点时,它们似乎不会随窗口缩放。下面的代码。
#define GLUT_DISABLE_ATEXIT_HACK
#include <GL/glut.h>
#include <GL/gl.h>
//#include <assert.h>
void init (void)
{
glClearColor (1.0, 1.0, 0.0, 0.0); /* Set background to yellow */
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}
void display(void)
{
glClear (GL_COLOR_BUFFER_BIT);
glColor3f (0.0, 0.0, 1.0);
glBegin(GL_TRIANGLES);
glVertex2d (0.0, 0.0);
glVertex2d(1.0, 0.0);
glVertex2d (0.5, 0.866);
glEnd();
glFlush (); //Display immediately
}
void keyEscape( unsigned char key, int x, int y )
{
switch ( key )
{
case 113: // 'Q' key for escape
int windowID = glutCreateWindow ("triangle");
glutDestroyWindow (windowID);
exit (0);
break;
}
glutPostRedisplay();
}
void mouseEscape( int button, int state, int x, int y )
{
if (button == GLUT_RIGHT_BUTTON && state == GLUT_DOWN)
{
int windowID = glutCreateWindow ("triangle");
glutDestroyWindow (windowID);
exit (0);
glutPostRedisplay();
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize (250, 250);
glutInitWindowPosition ((glutGet(GLUT_SCREEN_WIDTH)-250)/2, (glutGet(GLUT_SCREEN_HEIGHT)-250)/2);
glutCreateWindow ("triangle");
init ();
glutKeyboardFunc(keyEscape);
glutMouseFunc(mouseEscape);
glutDisplayFunc(display);
glutMainLoop();
return 0;
}
- 步骤1:去掉Init函数。投影设置是绘图过程的一部分
- 步骤2:使用窗口宽度作为glOrtho的左/右参数的输入
像这样:
void display(void)
{
int const win_width = glutGet(GLUT_WINDOW_WIDTH);
int const win_height = glutGet(GLUT_WINDOW_HEIGHT);
float const win_aspect = (float)win_width / (float)win_height;
glClearColor (1.0, 1.0, 0.0, 0.0); /* Set background to yellow */
glClear (GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, win_aspect, 0.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glColor3f (0.0, 0.0, 1.0);
glBegin(GL_TRIANGLES);
glVertex2d (0.0, 0.0);
glVertex2d(1.0, 0.0);
glVertex2d (0.5, 0.866);
glEnd();
glFlush (); // Tell OpenGL to process what we submitted so far
}
BTW:您应该切换到双缓冲模式,并使用glutSwapBuffers而不是glFlush/glFinish;在某些系统上,单缓冲模式不起作用(很好)。如今,唯一可靠的方法是双重缓冲。