效果如图
准备第三方库 glew、freeglut、glm
代码包括主程序源文件mainApp.cpp、顶点着色器shader.vs、片元着色器shader.fs
mainApp.cpp如下
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <GL/glew.h>
#include <GL/freeglut.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
using namespace std;
using namespace glm;
//shader文件
const char* vsShaderName = "shader.vs";//顶点着色器
const char* fsShaderName = "shader.fs";//片元着色器
GLuint VBO;//顶点缓冲对象
GLuint IBO;//索引缓冲对象
static GLfloat *vertices;//顶点数组
static unsigned int *indices; //索引数组
GLuint ShaderProgram;
GLuint MatrixID;
int windowWidth = 800;
int windowHeight = 800;
//球体参数
float radius=5.0f;//半径
int longPart=19;//经线数
int latPart=18;//纬线数
int verticeNum = longPart * latPart + 2 * longPart;
//相机参数
glm::mat4 ViewMatrix;//视图矩阵
glm::mat4 ProjectionMatrix; //投影矩阵
glm::mat4 MVP;//模型视图矩阵
glm::mat4 ModelMatrix;//模型矩阵
glm::vec3 position = glm::vec3(5, 5, 5); //相机位置
float horizontalAngle = 3.14f;
float verticalAngle = 0.0f;
float initialFoV = 45.0f; //相机视场角
float speed = 0.05f; //平移速度
float mouseSpeed = 0.05f;
int mouseX, mouseY;//鼠标位置 窗口坐标
// 传递键盘事件
static void SpecialKeyboardCB(int Key, int x, int y)
{
glm::vec3 direction(
cos(verticalAngle) * sin(horizontalAngle),
sin(verticalAngle),
cos(verticalAngle) * cos(horizontalAngle)
);
glm::vec3 right = glm::vec3(
sin(horizontalAngle - 3.14f / 2.0f),
0,
cos(horizontalAngle - 3.14f / 2.0f)
);
glm::vec3 up = glm::cross(right, direction);
switch (Key) {
case GLUT_KEY_UP:
position += direction * speed;
fprintf(stderr, "up key\n");
break;
case GLUT_KEY_RIGHT:
position += right * speed;
fprintf(stderr, "right key\n");
break;
case GLUT_KEY_DOWN:
position -= direction * speed;
fprintf(stderr, "down key\n");
break;
case GLUT_KEY_LEFT:
position -= right * speed;
fprintf(stderr, "left key\n");
break;
case GLUT_KEY_F4:
exit(1);
default:
fprintf(stderr, "Unimplemented GLUT key\n");
//exit(1);
}
float FoV = initialFoV;
ProjectionMatrix = glm::perspective(glm::radians(FoV), 4.0f / 3.0f, 0.1f, 100.0f);
ViewMatrix = glm::lookAt(
position,
position + direction,
up
);
ModelMatrix = glm::mat4(1.0);
MVP = ProjectionMatrix * ViewMatrix * ModelMatrix;
glutPostRedisplay();//设置窗口重绘
}
//传递鼠标事件
static void PassiveMouseCB(int x, int y)
{
horizontalAngle += mouseSpeed * float(x - mouseX);
verticalAngle += mouseSpeed * float(y - mouseY);
mouseX = x;
mouseY = y;
SpecialKeyboardCB(0, 0, 0);
}
//渲染回调函数
void RenderScenceCB() {
// 清空颜色缓存
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);//线框模式
//传递mvp
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]);
//传递顶点、索引
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO);
////test
//glDrawElements(GL_TRIANGLES, 3*4, GL_UNSIGNED_SHORT, 0);
glDrawElements(GL_TRIANGLES_ADJACENCY, (longPart - 1)* latPart * 3 * 2 * 4, GL_UNSIGNED_SHORT, 0);
glDisableVertexAttribArray(0);
//交换前后缓存
glutSwapBuffers();
}
//创建顶点
static void CreateVertexBuffer()
{
////test
//vertices = new GLfloat[3* 3];
//vertices[0] = -1.0f;
//vertices[1] = -1.0f;
//vertices[2] = -1.0f;
//vertices[3] = -1.0f;
//vertices[4] = -1.0f;
//vertices[5] = 1.0f;
//vertices[6] = -1.0f;
//vertices[7] = 1.0f;
//vertices[8] = 1.0f;
vertices= new GLfloat[verticeNum * 3];
for (int i = 0; i < longPart; i++)
{
vertices[i * 3] = 0;
vertices[i * 3 + 1] = 0;
vertices[i * 3 + 2] = radius;
}
float degreesToRadians = 3.141593f/ 180.0f; //弧度转换
float deltaLong = 360.0f / (longPart - 1);//经度每份对应度数
float deltaLat = 180.0f / (latPart + 2);//纬度每份对应度数
for (int tempLat = 0; tempLat < latPart; tempLat++)
{
float tempAngle1 = ((tempLat + 1)* deltaLat) * degreesToRadians;
for (int tempLong = 0; tempLong < longPart; tempLong++)
{
float tempAngle2 = (tempLong*deltaLong) * degreesToRadians;
int tempIndex = tempLong + tempLat* longPart + longPart;
vertices[tempIndex * 3] = sin(tempAngle1) * cos(tempAngle2)* radius;
vertices[tempIndex * 3 + 1] = sin(tempAngle1) * sin(tempAngle2)* radius;
vertices[tempIndex * 3 + 2] = cos(tempAngle1)* radius;
}
}
for (int i = 0; i < longPart; i++)
{
vertices[(verticeNum - 1 - i) * 3] = 0;
vertices[(verticeNum - 1 - i) * 3 + 1] = 0;
vertices[(verticeNum - 1 - i) * 3 + 2] = -1.0f*radius;
}
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
////test
//glBufferData(GL_ARRAY_BUFFER, 3 * 3 * sizeof(GLfloat), vertices, GL_STATIC_DRAW);
glBufferData(GL_ARRAY_BUFFER, verticeNum * 3 * sizeof(GLfloat), vertices, GL_STATIC_DRAW);
}
//创建索引
static void CreateIndexBuffer()
{
////test
//indices = new unsigned int[3];
//indices[0] = 2;
//indices[1] = 1;
//indices[2] = 0;
indices = new unsigned int[(longPart - 1)* latPart * 3 * 2];
int k = 0;
for (int i = 0; i < longPart - 1; i++)
{
indices[k++] = i;
indices[k++] = i + longPart;
indices[k++] = i + longPart + 1;
}
for (int tempLat = 0; tempLat < latPart-1; tempLat++)
{
for (int tempLong = 0; tempLong < longPart - 1; tempLong++)
{
indices[k++] = tempLong + tempLat * longPart + longPart;
indices[k++] = tempLong + tempLat * longPart + 2 * longPart;
indices[k++] = tempLong + tempLat * longPart + longPart + 1;
indices[k++] = tempLong + tempLat * longPart + 2 * longPart;
indices[k++] = tempLong + tempLat * longPart + 1 + 2 * longPart;
indices[k++] = tempLong + tempLat * longPart + 1 + longPart;
}
}
for (int i = 0; i < longPart - 1; i++)
{
indices[k++] = verticeNum - 1 - i;
indices[k++] = verticeNum - 1 - i - longPart;
indices[k++] = verticeNum - 2 - i - longPart;
}
glGenBuffers(1, &IBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO);
////test
//glBufferData(GL_ELEMENT_ARRAY_BUFFER, 3* sizeof(unsigned int), indices, GL_STATIC_DRAW);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, (longPart - 1)* latPart * 3 * 2 * sizeof(unsigned int), indices, GL_STATIC_DRAW);
}
// 使用shader文本编译shader对象，并绑定shader到着色器程序中
static void AddShader(GLuint ShaderProgram, const char* pShaderText, GLenum ShaderType)
{
// 根据shader类型参数定义两个shader对象
GLuint ShaderObj = glCreateShader(ShaderType);
// 检查是否定义成功
if (ShaderObj == 0) {
fprintf(stderr, "Error creating shader type %d\n", ShaderType);
exit(0);
}
// 定义shader的代码源
const GLchar* p[1];
p[0] = pShaderText;
GLint Lengths[1];
Lengths[0] = strlen(pShaderText);
glShaderSource(ShaderObj, 1, p, Lengths);
glCompileShader(ShaderObj);// 编译shader对象
// 检查和shader相关的错误
GLint success;
glGetShaderiv(ShaderObj, GL_COMPILE_STATUS, &success);
if (!success) {
GLchar InfoLog[1024];
glGetShaderInfoLog(ShaderObj, 1024, NULL, InfoLog);
fprintf(stderr, "Error compiling shader type %d: '%s'\n", ShaderType, InfoLog);
exit(1);
}
// 将编译好的shader对象绑定到program object程序对象上
glAttachShader(ShaderProgram, ShaderObj);
}
// 编译着色器函数
static void CompileShaders()
{
// 创建着色器程序
ShaderProgram = glCreateProgram();
// 检查是否创建成功
if (ShaderProgram == 0) {
fprintf(stderr, "Error creating shader program\n");
exit(1);
}
// 存储着色器文本的字符串
string vs, fs;
// 分别读取着色器文件中的文本到字符串
std::ifstream VertexShaderStream(vsShaderName, std::ios::in);
if (VertexShaderStream.is_open()) {
std::stringstream sstr;
sstr << VertexShaderStream.rdbuf();
vs = sstr.str();
VertexShaderStream.close();
}
else {
printf("Error to open %s\n", vsShaderName);
getchar();
exit(0);
}
std::ifstream FragmentShaderStream(fsShaderName, std::ios::in);
if (FragmentShaderStream.is_open()) {
std::stringstream sstr;
sstr << FragmentShaderStream.rdbuf();
fs = sstr.str();
FragmentShaderStream.close();
}
// 添加顶点着色器和片段着色器
AddShader(ShaderProgram, vs.c_str(), GL_VERTEX_SHADER);
AddShader(ShaderProgram, fs.c_str(), GL_FRAGMENT_SHADER);
// 链接shader着色器程序，并检查程序相关错误
GLint Success = 0;
GLchar ErrorLog[1024] = { 0 };
glLinkProgram(ShaderProgram);
glGetProgramiv(ShaderProgram, GL_LINK_STATUS, &Success);
if (Success == 0) {
glGetProgramInfoLog(ShaderProgram, sizeof(ErrorLog), NULL, ErrorLog);
fprintf(stderr, "Error linking shader program: '%s'\n", ErrorLog);
exit(1);
}
// 检查验证在当前的管线状态程序是否可以被执行
glValidateProgram(ShaderProgram);
glGetProgramiv(ShaderProgram, GL_VALIDATE_STATUS, &Success);
if (!Success) {
glGetProgramInfoLog(ShaderProgram, sizeof(ErrorLog), NULL, ErrorLog);
fprintf(stderr, "Invalid shader program: '%s'\n", ErrorLog);
exit(1);
}
// 设置到管线声明中来使用上面成功建立的shader程序
glUseProgram(ShaderProgram);
MatrixID = glGetUniformLocation(ShaderProgram, "gWVP");
}
int main(int argc, char ** argv) {
// 初始化GLUT
glutInit(&argc, argv);
// 显示模式：双缓冲、RGBA
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize(windowWidth, windowHeight);
glutInitWindowPosition(100, 100);
glutCreateWindow("sphere");
GLenum res = glewInit();
if (res != GLEW_OK) {
fprintf(stderr, "Error: '%s'\n", glewGetErrorString(res));
return 1;
}
// 开始渲染
glutDisplayFunc(RenderScenceCB);
// 注册键盘事件
glutSpecialFunc(SpecialKeyboardCB);
//注册鼠标事件
glutPassiveMotionFunc(PassiveMouseCB);
mouseX = windowWidth / 2;
mouseY = windowHeight / 2;
// 缓存清空后的颜色值
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
//创建顶点
CreateVertexBuffer();
//创建索引
CreateIndexBuffer();
// 编译着色器
CompileShaders();
//开启深度测试
glEnable(GL_DEPTH_TEST);
// 通知开始GLUT的内部循环
glutMainLoop();
delete vertices;
return 0;
}
shader.vs如下
#version 330
layout (location = 0) in vec3 Position;
// WVP标准
uniform mat4 gWVP;
void main()
{
gl_Position = gWVP * vec4(Position, 1.0);
}
shader.fs如下
#version 330
out vec3 FragColor;
void main()
{
FragColor = vec3(1.0, 0.0, 0.0);
}