将2D对象更改为3D对象OpenGl
我有一个代码，用于找到在棋盘中单击的单元格鼠标，然后2D三角形状转到单元格位置，现在我想将2D三角形更改为3D立方体，但我不知道该怎么做。
这是我的代码
#include <string>
#include <stdlib.h>
#ifdef __APPLE__
#include <OpenGL/OpenGL.h>
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#include <iostream>
using namespace std;
void init()
{
glClearColor (1.0, 0.0, 1.0, 0.0);
glShadeModel (GL_FLAT);
}
const int scl = 80 ;
const int STEP_SIZE = 80;
const int WIN_WIDTH = 800;
const int WIN_HEIGHT = 800;
int LeftRight = 0 ;
int UpDown = 0;
void moveRight()
{
LeftRight+=STEP_SIZE;
}
void moveLeft()
{
LeftRight-=STEP_SIZE;
}
void moveUp()
{
UpDown+=STEP_SIZE;
}
void moveDown()
{
UpDown-=STEP_SIZE;
}
void DrawBoard()
{
int x , y , color = 0;
glClear (GL_COLOR_BUFFER_BIT);
for(x=1; x<=8; x++)
{
if(color==0)
glColor3f (1.0, 0.0, 0.0), color++;
else
glColor3f (1.0, 1.0, 1.0),color=0;
for(y=1; y<=8; y++)
{
if(color==0)
glColor3f (0.0, 0.0, 0.0),color++;
else
glColor3f (1.0, 1.0, 1.0),color=0;
glBegin(GL_QUADS);
glVertex2f(scl+scl*x, scl+scl*y);
glVertex2f(scl*x, scl+scl*y);
glVertex2f(scl*x, scl*y);
glVertex2f(scl+scl*x, scl*y);
glEnd();
}
}
// This is the Triangle that will change to cube
glBegin(GL_QUADS);
glColor3f (1.0, 0.5, 0.0);
glVertex2f(90+LeftRight,100+UpDown);
glVertex2f(90+LeftRight,100+UpDown);
glVertex2f(120+LeftRight,140+UpDown);
glVertex2f(150+LeftRight,100+UpDown);
glEnd();
//--------------------------------------
glFlush ();
}
int mouse_x = -1 ;
int mouse_y = -1 ;
int object_x = -1 ;
int object_y = -1 ;
void moveObjectToFrom()
{
if (mouse_x > 8 || mouse_x < 1 || mouse_y > 8 || mouse_y < 1 )
return ;
if(object_x > mouse_x )
{
object_x-- ;
moveUp();
}
if(object_x < mouse_x )
{
object_x++;
moveDown();
}
if(object_y > mouse_y )
{
object_y-- ;
moveLeft();
}
if(object_y < mouse_y)
{
object_y++ ;
moveRight();
}
}
void mouseClicks( int button , int key, int x, int y )
{
// this variables related to chessboard
mouse_x = y / scl ;
mouse_y = 9 - (WIN_HEIGHT - x)/scl ;
object_x = 9 - (100 + UpDown)/ scl ;
object_y = 9 - (WIN_HEIGHT - (LeftRight+90))/scl ;
if (button !=0 || mouse_x > 8 || mouse_x < 1 || mouse_y > 8 || mouse_y < 1 )
return ;
glutPostRedisplay();
}
void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
gluOrtho2D (0.0, (GLdouble) w, 0.0, (GLdouble) h);
}
void update(int value)
{
moveObjectToFrom();
glutTimerFunc(50, update, 0);
glutPostRedisplay();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
// glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glEnable(GL_DEPTH_TEST);
glutInitWindowSize (WIN_WIDTH, WIN_HEIGHT);
glutInitWindowPosition (100,100);
glutCreateWindow (argv[0]);
glutTimerFunc(25, update, 0);
glutMouseFunc(mouseClicks);
init ();
glutDisplayFunc(DrawBoard);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
1 个答案:
答案 0 :(得分：1)
您的主要问题是GL_PROJECTION设置为gluOrtho2D，因此当您渲染轴对齐立方体时，它将始终生成正方形。要解决此问题，您应该使用gluProjection代替。但是，这会以0.0,0.0为中心，而不是当前的屏幕中心坐标(0.5*w,0.5*h)，因此您还需要翻译GL_MODELVIEW。
此处示例如何执行此操作：
现在要渲染一个立方体，你可以这样做：
void render_cube()
{
const GLfloat a=20.0; // cube half size
const GLfloat pos[]= // glVertex cube centered at (0,0,0) of size 2*a
{
// x y z
-a,+a,-a,
+a,+a,-a,
+a,-a,-a,
-a,-a,-a,
-a,-a,+a,
+a,-a,+a,
+a,+a,+a,
-a,+a,+a,
-a,-a,-a,
+a,-a,-a,
+a,-a,+a,
-a,-a,+a,
+a,-a,-a,
+a,+a,-a,
+a,+a,+a,
+a,-a,+a,
+a,+a,-a,
-a,+a,-a,
-a,+a,+a,
+a,+a,+a,
-a,+a,-a,
-a,-a,-a,
-a,-a,+a,
-a,+a,+a,
};
const GLfloat col[]=
{
// r g b
1.0,0.0,0.0,
1.0,0.0,0.0,
1.0,0.0,0.0,
1.0,0.0,0.0,
1.0,1.0,0.0,
1.0,1.0,0.0,
1.0,1.0,0.0,
1.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,1.0,
0.0,1.0,1.0,
0.0,1.0,1.0,
0.0,1.0,1.0,
0.0,0.0,1.0,
0.0,0.0,1.0,
0.0,0.0,1.0,
0.0,0.0,1.0,
1.0,1.0,1.0,
1.0,1.0,1.0,
1.0,1.0,1.0,
1.0,1.0,1.0,
};
const GLfloat nor[]= // glNormal
{
// nx ny nz
0.0, 0.0,-1.0,
0.0, 0.0,-1.0,
0.0, 0.0,-1.0,
0.0, 0.0,-1.0,
0.0, 0.0,+1.0,
0.0, 0.0,+1.0,
0.0, 0.0,+1.0,
0.0, 0.0,+1.0,
0.0,-1.0, 0.0,
0.0,-1.0, 0.0,
0.0,-1.0, 0.0,
0.0,-1.0, 0.0,
+1.0, 0.0, 0.0,
+1.0, 0.0, 0.0,
+1.0, 0.0, 0.0,
+1.0, 0.0, 0.0,
0.0,+1.0, 0.0,
0.0,+1.0, 0.0,
0.0,+1.0, 0.0,
0.0,+1.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
};
int i,i3;
glBegin(GL_QUADS);
for (i=0,i3=0;i<24;i++,i3+=3)
{
glColor3fv (col+i3);
glNormal3fv(nor+i3);
glVertex3fv(pos+i3);
}
glEnd();
}
应该像这样呈现：
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_CULL_FACE);
glFrontFace(GL_CCW);
render_cube();
只需将a常量设置为您需要的值，并将modelview转换为其展示位置......
这里预览：
每一面都有自己的颜色用于调试目的...在这里查看3D视图示例：
[Edit1]我稍稍调整了你的代码
多边形绕组存在一些不一致之处。尝试将这些函数与这些函数交换（它们对我有效）并保留其余代码：
//---------------------------------------------------------------------------
void render_cube(GLfloat a) // cube half size
{
GLfloat pos[]= // glVertex
{
// x y z
-a,+a,-a,
+a,+a,-a,
+a,-a,-a,
-a,-a,-a,
-a,-a,+a,
+a,-a,+a,
+a,+a,+a,
-a,+a,+a,
-a,-a,-a,
+a,-a,-a,
+a,-a,+a,
-a,-a,+a,
+a,-a,-a,
+a,+a,-a,
+a,+a,+a,
+a,-a,+a,
+a,+a,-a,
-a,+a,-a,
-a,+a,+a,
+a,+a,+a,
-a,+a,-a,
-a,-a,-a,
-a,-a,+a,
-a,+a,+a,
};
const GLfloat col[]= // glColor
{
// r g b
1.0,0.0,0.0,
1.0,0.0,0.0,
1.0,0.0,0.0,
1.0,0.0,0.0,
1.0,1.0,0.0,
1.0,1.0,0.0,
1.0,1.0,0.0,
1.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,0.0,
0.0,1.0,1.0,
0.0,1.0,1.0,
0.0,1.0,1.0,
0.0,1.0,1.0,
0.0,0.0,1.0,
0.0,0.0,1.0,
0.0,0.0,1.0,
0.0,0.0,1.0,
1.0,1.0,1.0,
1.0,1.0,1.0,
1.0,1.0,1.0,
1.0,1.0,1.0,
};
const GLfloat nor[]= // glNormal
{
// nx ny nz
0.0, 0.0,-1.0,
0.0, 0.0,-1.0,
0.0, 0.0,-1.0,
0.0, 0.0,-1.0,
0.0, 0.0,+1.0,
0.0, 0.0,+1.0,
0.0, 0.0,+1.0,
0.0, 0.0,+1.0,
0.0,-1.0, 0.0,
0.0,-1.0, 0.0,
0.0,-1.0, 0.0,
0.0,-1.0, 0.0,
+1.0, 0.0, 0.0,
+1.0, 0.0, 0.0,
+1.0, 0.0, 0.0,
+1.0, 0.0, 0.0,
0.0,+1.0, 0.0,
0.0,+1.0, 0.0,
0.0,+1.0, 0.0,
0.0,+1.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
-1.0, 0.0, 0.0,
};
int i,i3;
glBegin(GL_QUADS);
for (i=0,i3=0;i<24;i++,i3+=3)
{
glColor3fv (col+i3);
glNormal3fv(nor+i3);
glVertex3fv(pos+i3);
}
glEnd();
}
//---------------------------------------------------------------------------
void init()
{
glClearColor(1.0, 0.0, 1.0, 0.0);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
glEnable(GL_LIGHTING);
glEnable(GL_LIGHT0);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_CULL_FACE);
glFrontFace(GL_CCW);
}
//---------------------------------------------------------------------------
const int scl = 80 ;
int LeftRight = 0 ;
int UpDown = 0;
void DrawBoard()
{
int x , y , color = 0;
glClear (GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); // do not forget also to clear depth buffer
for(x=1;x<=8;x++)
{
if (color) glColor3f (0.0, 0.0, 0.0); // I like this a bit better then your approach
else glColor3f (1.0, 1.0, 1.0); color^=1;
for(y=1; y<=8; y++)
{
if (color) glColor3f (0.0, 0.0, 0.0);
else glColor3f (1.0, 1.0, 1.0); color^=1;
glBegin(GL_QUADS);
glNormal3f(0.0,0.0,+1.0);
glVertex3f(scl+scl*x, scl+scl*y,0.0);
glVertex3f(scl*x, scl+scl*y,0.0);
glVertex3f(scl*x, scl*y,0.0);
glVertex3f(scl+scl*x, scl*y,0.0);
glEnd();
}
}
// your triangle just above cube (and reversed order to match the rest of rendering)
glBegin(GL_QUADS);
glColor3f (1.0, 0.5, 0.0);
glNormal3f(0.0,0.0,+1.0);
glVertex3f(150+LeftRight,100+UpDown,scl+1.0);
glVertex3f(120+LeftRight,140+UpDown,scl+1.0);
glVertex3f( 90+LeftRight,100+UpDown,scl+1.0);
glVertex3f( 90+LeftRight,100+UpDown,scl+1.0);
glEnd();
// cube
glMatrixMode(GL_MODELVIEW);
glPushMatrix(); // remember modelview
glTranslatef(1.5*scl+LeftRight,1.5*scl+UpDown,+0.5*scl); // set cube position
render_cube(0.5*scl);
glPopMatrix(); // restore modelview
glFlush();
}
//---------------------------------------------------------------------------
void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60,float(w)/float(h),10.0,10000.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(-w/2,-h/2,-1000.0);
}
//---------------------------------------------------------------------------
使用800x800窗口，结果应如下所示：
btw。这些包含已过时：
#include <string>
#include <stdlib.h>
#include <iostream>
using namespace std;
因为您没有在代码中使用任何内容。
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