在OpenGL中使用glpecspective，gluLookAt [英] use glpecspective, gluLookAt in OpenGL
本文介绍了在OpenGL中使用glpecspective，gluLookAt的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我画1个四边形，这是成功的.当我调整窗口大小时，鼠标位置不好.它不会在鼠标所在的位置画一条线.我想使用glPerspective，gluLookAt
感谢您的帮助:
我的代码:
#include <stdio.h>
#include <glut.h>
int numLines;
typedef enum state{waitingforclick,clickedonce};
typedef struct point
{
int x;
int y;
}point;
point line[256][2];
int gState=waitingforclick;
bool lineisvalid=false;
int gHeight;
float gColor[3]={0,1,0};
void drawlines()
{
glColor3fv(gColor);
glBegin(GL_QUADS);
for(int i = 0;i<=numLines; i++)
{
glVertex2i(line[i][0].x,gHeight -line[i][0].y);
glVertex2i(line[i][1].x,gHeight-line[i][1].y);
}
glEnd();
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
drawlines();
glutSwapBuffers();
}
//for menu.you should ignore it
void menufunc(int val)
{
switch(val)
{
case 0:
gColor[0] = 1;
gColor[1] = 0;
gColor[2] = 0;
break;
case 1:
gColor[0] = 0;
gColor[1] = 1;
gColor[2] = 0;
break;
case 2:
gColor[0] = 0;
gColor[1] = 0;
gColor[2] = 1;
break;
}
}
//for menu.you should ignore it
void createMenu ()
{
int menu = glutCreateMenu(menufunc);
glutAddMenuEntry("Red", 0);
glutAddMenuEntry("green", 1);
glutAddMenuEntry("Blue", 2);
glutAttachMenu(GLUT_RIGHT_BUTTON);
}
void init()
{
glClearColor(0,0,0,1);
glMatrixMode(GL_PROJECTION);
//I can change glOrtho by gluPerspective ?
glOrtho(-1, 1.0, -1, 1.0, -1.0, 1.0);
numLines=- 1;
glMatrixMode(GL_MODELVIEW);
createMenu();
}
void reshape(int width, int height)
{
gHeight = height;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//I can change gluOrtho2D by gluLookAt ?
gluOrtho2D(0, width, 0, height);
glMatrixMode(GL_MODELVIEW);
}
void mouseclick(int button, int state,int x, int y)
{
//when mouse click
if (button == GLUT_LEFT_BUTTON && state == GLUT_UP)
{
switch (gState)
{
case waitingforclick:
printf("1 clicked");
++numLines;
//line position
line[numLines][0].x = x;
line[numLines][0].y = y;
line[numLines][1].x = x;
line[numLines][1].y = y;
line[numLines][2].x = x;
line[numLines][3].y = y;
gState++;
break;
case clickedonce:
printf("2 clicked");
line[numLines][1].x = x;
line[numLines][1].y = y;
gState = waitingforclick;
break;
}
}
glutPostRedisplay ();
}
void mousedrag(int x, int y)
{
if(gState == clickedonce)
{
line[numLines][1].x = x;
line[numLines][1].y = y;
}
glutPostRedisplay();
}
int main(int argc, char ** argv)
{
glutInit(& argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowPosition(100,100);
glutInitWindowSize(500,500);
glutCreateWindow("App");
glutReshapeFunc(reshape);
glutDisplayFunc(display);
glutMouseFunc(mouseclick);
glutPassiveMotionFunc(mousedrag);
init();
glutMainLoop();
return 0;
}
解决方案
如果我有x，y，z轴，我可以得到mouse2d到轴的距离?如何?
Hi,
I draw 1 quads.It is success. When I re-size the window, the mouse position is bad. It does not draw a line where the mouse is. I want to use glPerspective,gluLookAt
Thanks for the help:
my code:
#include <stdio.h>
#include <glut.h>
int numLines;
typedef enum state{waitingforclick,clickedonce};
typedef struct point
{
int x;
int y;
}point;
point line[256][2];
int gState=waitingforclick;
bool lineisvalid=false;
int gHeight;
float gColor[3]={0,1,0};
void drawlines()
{
glColor3fv(gColor);
glBegin(GL_QUADS);
for(int i = 0;i<=numLines; i++)
{
glVertex2i(line[i][0].x,gHeight -line[i][0].y);
glVertex2i(line[i][1].x,gHeight-line[i][1].y);
}
glEnd();
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
drawlines();
glutSwapBuffers();
}
//for menu.you should ignore it
void menufunc(int val)
{
switch(val)
{
case 0:
gColor[0] = 1;
gColor[1] = 0;
gColor[2] = 0;
break;
case 1:
gColor[0] = 0;
gColor[1] = 1;
gColor[2] = 0;
break;
case 2:
gColor[0] = 0;
gColor[1] = 0;
gColor[2] = 1;
break;
}
}
//for menu.you should ignore it
void createMenu ()
{
int menu = glutCreateMenu(menufunc);
glutAddMenuEntry("Red", 0);
glutAddMenuEntry("green", 1);
glutAddMenuEntry("Blue", 2);
glutAttachMenu(GLUT_RIGHT_BUTTON);
}
void init()
{
glClearColor(0,0,0,1);
glMatrixMode(GL_PROJECTION);
//I can change glOrtho by gluPerspective ?
glOrtho(-1, 1.0, -1, 1.0, -1.0, 1.0);
numLines=- 1;
glMatrixMode(GL_MODELVIEW);
createMenu();
}
void reshape(int width, int height)
{
gHeight = height;
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
//I can change gluOrtho2D by gluLookAt ?
gluOrtho2D(0, width, 0, height);
glMatrixMode(GL_MODELVIEW);
}
void mouseclick(int button, int state,int x, int y)
{
//when mouse click
if (button == GLUT_LEFT_BUTTON && state == GLUT_UP)
{
switch (gState)
{
case waitingforclick:
printf("1 clicked");
++numLines;
//line position
line[numLines][0].x = x;
line[numLines][0].y = y;
line[numLines][1].x = x;
line[numLines][1].y = y;
line[numLines][2].x = x;
line[numLines][3].y = y;
gState++;
break;
case clickedonce:
printf("2 clicked");
line[numLines][1].x = x;
line[numLines][1].y = y;
gState = waitingforclick;
break;
}
}
glutPostRedisplay ();
}
void mousedrag(int x, int y)
{
if(gState == clickedonce)
{
line[numLines][1].x = x;
line[numLines][1].y = y;
}
glutPostRedisplay();
}
int main(int argc, char ** argv)
{
glutInit(& argc, argv);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutInitWindowPosition(100,100);
glutInitWindowSize(500,500);
glutCreateWindow("App");
glutReshapeFunc(reshape);
glutDisplayFunc(display);
glutMouseFunc(mouseclick);
glutPassiveMotionFunc(mousedrag);
init();
glutMainLoop();
return 0;
} 解决方案
If I have axis x,y,z,I can get distance mouse2d to axes?how?
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