Question

我无法弄清楚如何将鼠标拖动转换为围绕图像平面的Ox和Oy的旋转我跟随here的第一个答案，我将modelView矩阵存储在一个数组中，并在每次鼠标移动时更新它。 alpha和beta与前一个位置的鼠标增量成正比。

此代码在鼠标移动时更新旋转：

glLoadMatrixf(currentModelViewMatrix);
glRotatef(beta,0,1,0);
glRotatef(alpha,1,0,0);
glGetFloatv(GL_MODELVIEW_MATRIX, currentModelViewMatrix);

我从this解释结束时尝试了解决方案，但没有任何区别。

只有beta给出的旋转是绝对的，alpha给出的旋转是围绕模型中的轴，当绕第一轴旋转时，该轴会转动。我不知道如何使第二次旋转绝对。它现在的方式对用户来说似乎并不直观。

修改增量代码：

GLfloat currentModelViewMatrix[16];
GLfloat whole[16];
void glob()
{ 
  glLoadIdentity();
  glRotatef(beta,0,1,0);
  glRotatef(alpha,1,0,0);
  glMultMatrixf(currentModelViewMatrix);
  glGetFloatv(GL_MODELVIEW_MATRIX, currentModelViewMatrix); 

  glLoadIdentity();
  glTranslatef(0,0,-20);
  glMultMatrixf(currentModelViewMatrix);
  glGetFloatv(GL_MODELVIEW_MATRIX,whole); 

  alpha=beta=0;
}

在每个模型之前，矩阵都会加载：

glLoadMatrixf(whole);

完整代码：

#include "math.h"
#include "string.h"
#include "stdio.h"
#include "GL/freeglut.h"
#include "GL/gl.h"
#include "GL/glu.h"
float alpha,beta;

void key(int key, int x, int y)
{   printf("%d",key);
    switch(key)
    {   case GLUT_KEY_RIGHT:
            printf("right\n");
            break;
        case GLUT_KEY_LEFT:
            printf("left\n");
            break;
        case GLUT_KEY_UP:
            printf("top\n");
            break;
        case GLUT_KEY_DOWN:
            printf("bottom\n");
            break;
    }
    glutPostRedisplay();
    fflush(stdout); 
}

void otherkeys(unsigned char key,int x,int y)
{   printf("%c\n",key);
    fflush(stdout);
    switch(key)
    {   case '+':
            printf("plus\n");
            break;
        case '-':
            printf("minus\n");
            break;
        case 'w':
                alpha+=10;
            break;
        case 's':
                alpha-=10;
            break;
        case 'd':
                beta+=10;
            break;
        case 'a':
                beta-=10;
            break;
    }
    glutPostRedisplay();
}
void drawCube()
{   int i,j,d;
    glBegin(GL_LINES);
        for(i=0;i<8;i++)
        {   for(j=i+1;j<8;j++)
            {   d=j^i;
                if(d==1||d==2||d==4)
                {   glVertex3i(i%2,i/2%2,i/4%2 );   
                    glVertex3i(j%2,j/2%2,j/4%2 );   
                }                   
            }
        }
    glEnd();
}

GLfloat currentModelViewMatrix[16];
GLfloat whole[16];
void glob()
{   
    glLoadIdentity();
    glRotatef(beta,0,1,0);
    glRotatef(alpha,1,0,0);
    glMultMatrixf(currentModelViewMatrix);
    glGetFloatv(GL_MODELVIEW_MATRIX, currentModelViewMatrix);   

    glLoadIdentity();
    glTranslatef(0,0,-20);
    glMultMatrixf(currentModelViewMatrix);
    glGetFloatv(GL_MODELVIEW_MATRIX,whole); 

    alpha=beta=0;
}
void renderFunction()
{   int i;
    glClearColor(0.0,0.0,0.0,0.0);
    glClear(GL_COLOR_BUFFER_BIT);   
    glColor3f(1.0,1.0,1.0); 
    glMatrixMode(GL_PROJECTION); 
        glLoadIdentity();
//              glRotatef(angle2,0.0,0.0,1.0);
        gluPerspective(60, 1.333, 0.1, 100);

    glMatrixMode(GL_MODELVIEW);

    glColor3f(1.0,0.0,0.0); 
    for(i=1;i<8;i++)
    {   
        glLoadMatrixf(whole);   
        glTranslatef(i*2.0,0,0);
        drawCube();
    }

    glColor3f(0.0,1.0,0.0); 
    for(i=1;i<6;i++)
    {
        glLoadMatrixf(whole);   
        glTranslatef(0,i*2.0,0);
        drawCube();
    }

    glColor3f(0.0,0.0,1.0); 
    for(i=0;i<5;i++)
    {
        glLoadMatrixf(whole);   
        glTranslatef(0,0,i*2.0);
        drawCube();
    }

    glFlush();
}

/*mouse*/
int prevx,prevy,dx,dy;
void rotate(int dx,int dy)
{   printf("%f %f\n",dy/10.0,dy/10.0);
    alpha=dy/2.0;
    beta=dx/2.0;
    glob();
}

void passive(int x,int y)
{   prevx=x;prevy=y;}

void active(int x,int y)
{   dx=x-prevx;
    prevx=x;
    dy=y-prevy;
    prevy=y;
    rotate(dx,dy);
}

void globinit()
{
    glLoadIdentity();
    glGetFloatv(GL_MODELVIEW_MATRIX, currentModelViewMatrix);   

    glLoadIdentity();
    glTranslatef(0,0,-20);
    glGetFloatv(GL_MODELVIEW_MATRIX, whole);    
}
int main (int argc, char* argv[])
{       
    glutInit(&argc,argv);

    glutInitDisplayMode(GLUT_SINGLE);
    glutInitWindowSize(800,600);
    glutInitWindowPosition(100,100);
    glutCreateWindow("Open GL bla bla");
    glutDisplayFunc(renderFunction);
    glutIdleFunc(renderFunction);
    glutSpecialFunc(key);
    glutKeyboardFunc(otherkeys);
    glutMotionFunc(active);
    glutPassiveMotionFunc(passive);
    globinit();
    glutMainLoop(); 
    return 0;
}

Answer 1

尝试以下方法：

glLoadIdentity();
glRotatef(beta,0,1,0);
glRotatef(alpha,1,0,0);
glMultMatrixf(currentModelViewMatrix);
glGetFloatv(GL_MODELVIEW_MATRIX, currentModelViewMatrix);

由于订单已更改，旋转将在全局坐标系中执行，而不是在本地坐标系中执行。

围绕绝对轴旋转3d模型

1 个答案: