在 OpenGL 上单击鼠标时无法旋转和更改对象的颜色

Posted 2023-02-22

【中文标题】在 OpenGL 上单击鼠标时无法旋转和更改对象的颜色

【英文标题】：Can't rotate and change color of object on mouseclick on OpenGL

【发布时间】：2019-10-29 15:10:29

【问题描述】：

当我单击鼠标左键时，我试图围绕他自己的中心旋转一个对象，但它似乎不起作用......另外，当我右键单击鼠标时，我应该更改对象的颜色，但我不明白为什么它似乎不起作用，它只是停止了对象的旋转.....这是我的代码可以帮助你，我添加了所有函数以查看我正在尝试做什么：

#include <stdlib.h>
#include <math.h>
#include "dependente\freeglut\freeglut.h"
#include "dependente\glfw\glfw3.h"
#include <stdio.h> //incluziuni librarii

float ORG[3] =  0,0,0 ;
static GLfloat spin = 0.0;
GLfloat viewangle = 0, tippangle = 0, traj[120][3]; //variabila pentru unghi camera

GLfloat d[3] =  0.1, 0.1, 0.1 ; //vector directie

GLfloat  xAngle = 0.0, yAngle = 0.0, zAngle = 0.0;
bool draw_triangle = false; //variabila desenat figuri 
bool draw_square = false;
bool draw_decagon = false;

//  Use arrow keys to rotate entire scene !!!

void Special_Keys(int key, int x, int y) //functie ptr taste sus jos stanga dreapta

    switch (key) 

    case GLUT_KEY_LEFT:  viewangle -= 5;  break;
    case GLUT_KEY_RIGHT:  viewangle += 5;  break;
    case GLUT_KEY_UP:  tippangle -= 5;  break;
    case GLUT_KEY_DOWN:  tippangle += 5;  break;

    default: printf("Special key %c == %d", key, key);
    

    glutPostRedisplay();

void Triangle(void) //draw the triangle shape

    glBegin(GL_TRIANGLE_FAN);//triangles have a common vertex, which is the central vertex
    glColor3f(1.0f, 0.0f, 0.0f); glVertex3f(0.0f, 1.0f, 0.0f);   //V0(red)
    glColor3f(0.0f, 1.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 1.0f);   //V1(green)
    glColor3f(0.0f, 0.0f, 1.0f); glVertex3f(1.0f, -1.0f, 1.0f);   //V2(blue)
    glEnd();

void Square(void) 
    glBegin(GL_QUADS);
    glVertex2f(-1.0f, 1.0f); // top left
    glVertex2f(1.0f, 1.0f); // top right 
    glVertex2f(1.0f, -1.0f); // bottom right
    glVertex2f(-1.0f, -1.0f); // bottom left
    glEnd();

void Decagon(void) //draw the decagon shape

    glBegin(GL_POLYGON);
                glColor3f(0.0f, 0.0f, 1.0f);
                glVertex3f(0.72f,0.8f, 0.0f); //a1
                glVertex3f(0.52f,   0.8f,0.0f);  //z
                glVertex3f(0.35f,   0.64f, 0.0f); //b1
                glVertex3f(0.3f,   0.48f, 0.0f); //d1
                glVertex3f(0.35f,   0.3f, 0.0f); //e1
                glVertex3f(0.52f, 0.16f, 0.0f); //l1
                glVertex3f(0.72f, 0.16f, 0.0f); //m1
                glVertex3f(0.9f, 0.3f, 0.0f); //o1
                glVertex3f(0.95f, 0.48f, 0.0f); //p1
                glVertex3f(0.9f, 0.64f, 0.0f); //c1
                glScalef(10, 10, 10);
                glTranslatef(1, 2, 3);
    glEnd();


void Keyboard(unsigned char key, int x, int y) //press a key to perform actions

    switch (key) 

    case 'd': d[0] += 0.1;  break; //camera right
    case 'a': d[0] -= 0.1;  break; //camera left
    case 'w': d[1] += 0.1;  break; //camera up 
    case 's': d[1] -= 0.1;  break; //camera down 
    case 'm': d[2] += 0.1;  break; //magnify
    case 'n': d[2] -= 0.1;  break; //minify
    case 't': draw_triangle = true; draw_decagon = false;   break; //draw pyramid when key is pressed
    case 'q': draw_square = true; draw_decagon = false; draw_triangle = false; break; //draw cube when key is pressed
    case 'l': draw_decagon = true; draw_triangle = false; break; //draw prism when key is pressed

    case 'x': xAngle += 5;  break; //modify x axis angle
    case 'y': yAngle += 5;  break; //modify y axis angle
    case 'z': zAngle += 5;  break;  //modify z axis angle

    default: printf("   Keyboard %c == %d", key, key); //see what key it's pressed
    

    glutPostRedisplay();


void spinDisplay()

    spin = spin + 0.1;
    if (spin > 360.0)
    
        spin = 0.0;
    
    glutPostRedisplay();

void mouse(int buton, int state, int x, int y)

    switch (buton) 
    case GLUT_LEFT_BUTTON:
        if (state == GLUT_DOWN)
            glutIdleFunc(spinDisplay);
        break;
    case GLUT_RIGHT_BUTTON: //here I don't know how to change the color of the shape
        glutIdleFunc(NULL);
    default:glutIdleFunc(NULL);

        break;
    

void redraw(void)


    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glEnable(GL_DEPTH_TEST);

    glLoadIdentity();

    glTranslatef(0, 0, -3);
    glRotatef(tippangle, 1, 0, 0);  // Up and down arrow keys 'tip' view.
    glRotatef(viewangle, 0, 1, 0);  // Right/left arrow keys 'turn' view.

    glDisable(GL_LIGHTING);


    glPushMatrix();
    glTranslatef(d[0], d[1], d[2]);    // Move box down X axis.
    glScalef(0.3f, 0.3f, 0.3f); //increase the object size
    glRotatef(zAngle, 0, 0, 1);
    glRotatef(yAngle, 0, 1, 0);
    glRotatef(xAngle, 1, 0, 0);
    glRotatef(spin, 0.0, 0.0, 1.0);

    if (draw_triangle)
        Triangle();

    if (draw_decagon)
        Decagon();
    if (draw_square)
        Square();

    glPopMatrix();

    glutSwapBuffers();


int main(int argc, char** argv)

    glutInit(&argc, argv);
    glutInitWindowSize(900, 600);
    glutInitWindowPosition(300, 300);
    glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE);
    glutMouseFunc(mouse);
    glutCreateWindow("Figure Rotation");
    glutDisplayFunc(redraw);
    glutKeyboardFunc(Keyboard);
    glutSpecialFunc(Special_Keys);

    glClearColor(0.1, 0.0, 0.1, 1.0);

    glMatrixMode(GL_PROJECTION);//specify which matrix is the current matrix, matrix that represents your camera's lens (aperture, far-field, near-field, etc).
    gluPerspective(60, 1.5, 1, 10); //set up a perspective projection matrix
    glMatrixMode(GL_MODELVIEW); //specify which matrix is the current matrix,matrix that represents your camera (position, pointing, and up vector).
    glutMainLoop();

    return 1;

【问题讨论】：

代码中没有调用函数void mouse()。

尽量不要多标签。这是 C 还是 C++？

是的，你可能只是忘了打电话给glutMouseFunc 或者不管它的名字是什么。

谢谢，我太笨了..但是现在如果我右键单击它不会改变颜色，它只会停止旋转

如果我右键单击它不会改变颜色，它只会停止旋转这就是我所期望的：case GLUT_LEFT_BUTTON: if (state == GLUT_DOWN) glutIdleFunc(spinDisplay); break; case GLUT_RIGHT_BUTTON: glutIdleFunc(NULL);

【参考方案1】：

您必须声明一个表示形状颜色的变量。就像你改变绘制三角形或十边形一样。

声明全局变量：

bool colorChanged = false;

在鼠标函数中更改此变量，并添加 glutPostRedisplay 调用（否则将不会调用显示函数）。

colorChanged = !colorChanged;
glutPostRedisplay();

渲染时考虑这个变量。

if (colorChanged) 
    glColor3f(0,0,0); 
else 
    glColor3f(1,1,1); 

小心这个：

glutMouseFunc(mouse);
glutCreateWindow("Figure Rotation");

您在创建窗口之前注册了鼠标功能。一些实现会忽略此调用。