OpenGL画旋转立方体

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内容

  1. 设置颜色
  2. 设置顶点坐标
  3. 根据点画 面
  4. 根据面画体并设置颜色
  5. Init函数
  6. reshape函数
  7. mouse跟踪函数
  8. 设置旋转角度
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#include <windows.h>
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#include <bits/stdc++.h>
using namespace std;

GLfloat colors[][3] = { //
    {1, 0, 0},{0, 1, 0},{0, 0, 1},{1, 1, 0},{0, 1, 1},{1, 0, 1}
};
GLfloat vertices[][3] = { //
    {-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, -1.0, -1.0},{-1.0, 1.0, -1.0},
    {1.0, 1.0, -1.0},{1.0, -1.0, -1.0} 
};

void reshape(int w, int h){
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-4.0, 4.0, -4.0, 4.0, -4.0, 4.0);
}

void polygon(int a, int b, int c, int d){
    glBegin(GL_POLYGON);
        glVertex3fv(vertices[a]);
        glVertex3fv(vertices[b]);
        glVertex3fv(vertices[c]);
        glVertex3fv(vertices[d]);
    glEnd();
}

void colorcube(){
    glColor3fv(colors[0]); polygon(0, 3, 2, 1);
    glColor3fv(colors[1]); polygon(2, 3, 7, 6);
    glColor3fv(colors[2]); polygon(0, 4, 7, 3);
    glColor3fv(colors[3]); polygon(1, 2, 6, 5);
    glColor3fv(colors[4]); polygon(4, 5, 6, 7);
    glColor3fv(colors[5]); polygon(0, 1, 5, 4);
}

void init(){
    glClearColor(1, 1, 1, 1);
    glColor3f(0, 0, 0);
    glEnable(GL_DEPTH_TEST); //设置消隐
}

int axis;
float theta[3];
void mouse(int btn, int state, int x, int y){
    if(btn == GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0;
    if(btn == GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1;
    if(btn == GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2;
}

void spinCube(){
    theta[axis] += 0.05;
    if(theta[axis] > 360) theta[axis] -= 360;
    glutPostRedisplay();
}

void display(){
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); //记得清除DEPTH_BUFFER
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(1, 1, 1, 0, 0, 0, 0, 1, 0);

    glRotatef(theta[0], 1, 0, 0);
    glRotatef(theta[1], 0, 1, 0);
    glRotatef(theta[2], 0, 0, 1);
    colorcube();
    glutSwapBuffers();
}
int main(int argc, char** argv){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("SpinCube");

    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutMouseFunc(mouse);
    glutIdleFunc(spinCube);
    init();

    glutMainLoop();
}

光照版本

《OpenGL编程基础(第三版)》中文版教程的 6.6-P130旋转立方体的明暗计算 中的法向量的设置有误，和书中前面章节设置的面不符。

一般设置光照时也都会设置物体的材质，因为在启用光照后原来的函数 $glcolor()$ 函数不会起作用，用设置材质来替代原来的颜色设置。设置物体材质并不是设置物体的真实属性，设置的是光照到物体上的反射光效果，所以随着光源颜色的变化物体呈现的颜色也是不同的。

设置光照和材质的一般的步骤

  1. 设定要用的材质和光照
  2. 设定结构体指针，便于修改材质和光照属性
  3. 设置键盘和鼠标监控函数
  4. 指定每个面的法向量
  5. 设定旋转参数，确定旋转方向和速度
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#include <windows.h>
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#include <bits/stdc++.h>
using namespace std;
#include <stdlib.h>
const double PI = acos(-1.0);

typedef struct materialStruct{ // Material
    GLfloat ambient[4];
    GLfloat diffuse[4];
    GLfloat specular[4];
    GLfloat shininess;
}materialStruct;

void materials(materialStruct *materials){ // Set material
    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT, materials->ambient);
    glMaterialfv(GL_FRONT_AND_BACK, GL_DIFFUSE, materials->diffuse);
    glMaterialfv(GL_FRONT_AND_BACK, GL_SPECULAR, materials->specular);
    glMaterialf(GL_FRONT_AND_BACK, GL_SHININESS, materials->shininess);
}

materialStruct brassMaterials = { // brass
    {0.33, 0.22, 0.03, 1.0},
    {0.78, 0.57, 0.11, 1.0},
    {0.99, 0.91, 0.81, 1.0},
    27.8
};
materialStruct redPlasticMaterials = { // redPlastic
    {0.3, 0.0, 0.0, 1.0},
    {0.6, 0.0, 0.0, 1.0},
    {0.8, 0.6, 0.6, 1.0},
    32.0
};
materialStruct whiteShinyMaterials = { // whiteShiny
    {1.0, 1.0, 1.0, 1.0},
    {1.0, 1.0, 1.0, 1.0},
    {1.0, 1.0, 1.0, 1.0},
    100.0
};

typedef struct lightingStruct{ //Lighting
    GLfloat ambient[4];
    GLfloat diffuse[4];
    GLfloat specular[4];
}lightingStruct;

void lighting(lightingStruct *lighting){
    glLightfv(GL_LIGHT0, GL_AMBIENT, lighting->ambient);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, lighting->diffuse);
    glLightfv(GL_LIGHT0, GL_SPECULAR, lighting->specular);
}

lightingStruct whiteLighing = { // whiteLighting
    {0, 0, 0, 1},
    {1, 1, 1, 1},
    {1, 1, 1, 1}
};
lightingStruct coloredLighting = { // coloredLighting
    {0.2, 0, 0, 1},
    {0, 1, 0, 1},
    {0, 0, 1, 1}
};
GLfloat light0_pos[4] = {0.9, 0.9, 2.25, 0}; // LightPostion

materialStruct *currentMaterials;
lightingStruct *currentLighting;

GLfloat normals[][3] = { //
    {0.0, 0.0, 1.0},{1.0, 0.0, 0.0},
    {0.0,-1.0,0.0},{0.0,1.0,0.0},
    {0.0,0.0,-1.0},{-1.0,0.0,0.0}
};

GLfloat vertices[][3] = { //
    {-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, -1.0, -1.0},{-1.0, 1.0, -1.0},
    {1.0, 1.0, -1.0},{1.0, -1.0, -1.0} 
};

void reshape(int w, int h){
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    glOrtho(-4.0, 4.0, -4.0, 4.0, -4.0, 4.0);
}

void polygon(int a, int b, int c, int d){
    glBegin(GL_POLYGON);
        glVertex3fv(vertices[a]);
        glVertex3fv(vertices[b]);
        glVertex3fv(vertices[c]);
        glVertex3fv(vertices[d]);
    glEnd();
}

void colorcube(){
    // 设置法线
    glNormal3fv(normals[0]); polygon(0, 3, 2, 1);
    glNormal3fv(normals[1]); polygon(2, 3, 7, 6);
    glNormal3fv(normals[2]); polygon(0, 4, 7, 3);
    glNormal3fv(normals[3]); polygon(1, 2, 6, 5);
    glNormal3fv(normals[4]); polygon(4, 5, 6, 7);
    glNormal3fv(normals[5]); polygon(0, 1, 5, 4);
}

void init(){ // Active & Initive Lighting
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);

    currentMaterials = &redPlasticMaterials;
    materials(currentMaterials);

    currentLighting = &whiteLighing;
    lighting(currentLighting);
    glLightfv(GL_LIGHT0, GL_POSITION, light0_pos);
}

int axis;
float theta[3];
void mouse(int btn, int state, int x, int y){
    if(btn == GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0;
    if(btn == GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1;
    if(btn == GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2;
}
void spinCube(){
    theta[axis] += 0.05;
    if(theta[axis] > 360) theta[axis] -= 360;
    glutPostRedisplay();
}
void display(){
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(1, 1, 1, 0, 0, 0, 0, 1, 0);

    glRotatef(theta[0], 1, 0, 0);
    glRotatef(theta[1], 0, 1, 0);
    glRotatef(theta[2], 0, 0, 1);

    colorcube();
    glutSwapBuffers();
}
void key(unsigned char k, int x, int y){
    switch(k){
    case '1': glutIdleFunc(NULL); break;
    case '2': glutIdleFunc(spinCube); break;
    case '3': currentMaterials = &redPlasticMaterials; break;
    case '4': currentMaterials = &whiteShinyMaterials; break;
    case '5': currentMaterials = &brassMaterials; break;
    case '6': currentLighting = &whiteLighing; break;
    case '7': currentLighting = &coloredLighting; break;
    case 'q': exit(0); break;
    }
    materials(currentMaterials);
    lighting(currentLighting);

    glutPostRedisplay();
}

int main(int argc, char** argv){
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("SpinCube");

    glutReshapeFunc(reshape);
    glutDisplayFunc(display);
    glutMouseFunc(mouse);
    glutIdleFunc(spinCube);
    glutKeyboardFunc(key);
    init();

    glutMainLoop();
}
# 使用单$作为行内数学公式分界符