来源：《Computer Graphics Programming in OpenGL Using C++ 》by V Scott
Gordon John L Clevenger
内容：程序6.1 Sphere，书P135页，PDF153/403

生成

以下将图片贴图到生成的球体形成效果

完整代码

一共有 8 个文件，名字如下：

220301 6.1 Sphere.cpp
6.1 Shpere.cpp
6.1 Shpere.h
5.2 Utils.cpp
5.2 Utils.h
5.2 vertShader.glsl
5.2 fragShader.glsl
brick1.jpg
6.1 earth.jpg

220301 6.1 Sphere.cpp

#include <string>
#include <iostream>
#include <fstream>
#include <cmath>#include "glm\glm.hpp"
#include "glm\gtc\type_ptr.hpp"
#include "glm\gtc\matrix_transform.hpp"
#include "Utils\6.1 Sphere.h"
#include "Utils\5.2 Utils.h"
using namespace std;
#define numVAOs 1
#define numVBOs 3
float cameraX, cameraY, cameraZ;
float pyrLocX, pyrLocY, pyrLocZ;
GLuint renderingProgram;
GLuint vao[numVAOs];
GLuint vbo[numVBOs];
GLuint brickTexture; // 纹理图片ID// allocate variables used in display() function,
// so that they won’t need to be allocated during rendering
GLuint mvLoc, projLoc;
int width, height;
float aspect;
glm::mat4 pMat, vMat, mMat, mvMat;Sphere mySphere(48); // 声明一个球的classvoid setupVertices(void) {std::vector<int> ind = mySphere.getIndices(); // 球体点的标注std::vector<glm::vec3> vert = mySphere.getVertices(); // 球上的顶点std::vector<glm::vec2> tex = mySphere.getTexCoords(); // 纹理坐标std::vector<glm::vec3> norm = mySphere.getNormals(); // 球上法向量std::vector<float> pvalues; // vertex positions 顶点位置std::vector<float> tvalues; // texture coordinates 纹理坐标std::vector<float> nvalues; // normal vectors 法向量int numIndices = mySphere.getNumIndices();for (int i = 0; i < numIndices; i++) {     // 把每一个点上的坐标（x,y,z），纹理坐标（s，t），法向量(a,b,c)存储进对应数组pvalues.push_back((vert[ind[i]]).x);pvalues.push_back((vert[ind[i]]).y);pvalues.push_back((vert[ind[i]]).z);tvalues.push_back((tex[ind[i]]).s);tvalues.push_back((tex[ind[i]]).t);nvalues.push_back((norm[ind[i]]).x);nvalues.push_back((norm[ind[i]]).y);nvalues.push_back((norm[ind[i]]).z);}glGenVertexArrays(1, vao);glBindVertexArray(vao[0]);glGenBuffers(numVBOs, vbo);// put the vertices into buffer #0  第一个是顶点放入缓存器中glBindBuffer(GL_ARRAY_BUFFER, vbo[0]);glBufferData(GL_ARRAY_BUFFER, pvalues.size() * 4, &pvalues[0], GL_STATIC_DRAW);// put the texture coordinates into buffer #1  第二个是将纹理坐标放入缓存器中glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);glBufferData(GL_ARRAY_BUFFER, tvalues.size() * 4, &tvalues[0], GL_STATIC_DRAW);// put the normals into buffer #2   第三个是将法向量放入缓存器中glBindBuffer(GL_ARRAY_BUFFER, vbo[2]);glBufferData(GL_ARRAY_BUFFER, nvalues.size() * 4, &nvalues[0], GL_STATIC_DRAW);
}
void init(GLFWwindow* window) {renderingProgram = createShaderProgram("add/5.2 vertShader.glsl", "add/5.2 fragShader.glsl");cameraX = 0.0f; cameraY = 0.0f; cameraZ = 8.0f;pyrLocX = 1.0f; pyrLocY = -1.0f; pyrLocZ = 0.0f; // shift down Y to reveal perspectivesetupVertices();brickTexture = loadTexture("add/6.1 earth.jpg"); // 加载纹理的图片
}void display(GLFWwindow* window, double currentTime) {glClear(GL_DEPTH_BUFFER_BIT);glUseProgram(renderingProgram);// get the uniform variables for the MV and projection matricesmvLoc = glGetUniformLocation(renderingProgram, "mv_matrix");projLoc = glGetUniformLocation(renderingProgram, "proj_matrix");// build perspective matrixglfwGetFramebufferSize(window, &width, &height);aspect = (float)width / (float)height;pMat = glm::perspective(1.0472f, aspect, 0.1f, 1000.0f); // 1.0472 radians = 60 degrees// build view matrix, model matrix, and model-view matrixvMat = glm::translate(glm::mat4(1.0f), glm::vec3(-cameraX, -cameraY, -cameraZ));// vbo[0]mMat = glm::translate(glm::mat4(1.0f), glm::vec3(pyrLocX, pyrLocY, pyrLocZ));mvMat = vMat * mMat;// copy perspective and MV matrices to corresponding uniform variablesglUniformMatrix4fv(mvLoc, 1, GL_FALSE, glm::value_ptr(mvMat));glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(pMat));// associate VBO with the corresponding vertex attribute in the vertex shaderglBindBuffer(GL_ARRAY_BUFFER, vbo[0]);glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);glEnableVertexAttribArray(0);// 纹理glBindBuffer(GL_ARRAY_BUFFER, vbo[1]);glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, 0);glEnableVertexAttribArray(1);glActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, brickTexture);// adjust OpenGL settings and draw modelglEnable(GL_DEPTH_TEST);glDepthFunc(GL_LEQUAL);glFrontFace(GL_CCW);// 锥体的三角形是逆时针的面认为是正方向glDrawArrays(GL_TRIANGLES, 0, mySphere.getNumIndices());}int main(void) { // main() is unchanged from beforeif (!glfwInit()) { exit(EXIT_FAILURE); }glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);GLFWwindow* window = glfwCreateWindow(600, 600, "Chapter 6 - program 1", NULL, NULL);glfwMakeContextCurrent(window);if (glewInit() != GLEW_OK) { exit(EXIT_FAILURE); }glfwSwapInterval(1);init(window);while (!glfwWindowShouldClose(window)) {display(window, glfwGetTime());glfwSwapBuffers(window);glfwPollEvents();}glfwDestroyWindow(window);glfwTerminate();exit(EXIT_SUCCESS);
}

6.1 Shpere.cpp

#include <cmath>
#include <vector>
#include <iostream>
#include <glm\glm.hpp>
#include "6.1 Sphere.h"
using namespace std;
Sphere::Sphere() {init(48);
}
Sphere::Sphere(int prec) { // prec is precision, or number of slicesinit(prec);
}
float Sphere::toRadians(float degrees) { return (degrees * 2.0f * 3.14159f) / 360.0f; }
void Sphere::init(int prec) {numVertices = (prec + 1) * (prec + 1);numIndices = prec * prec * 6;for (int i = 0; i < numVertices; i++) { vertices.push_back(glm::vec3()); } // std::vector::push_back()for (int i = 0; i < numVertices; i++) { texCoords.push_back(glm::vec2()); } // inserts new element atfor (int i = 0; i < numVertices; i++) { normals.push_back(glm::vec3()); } // the end of a vector andfor (int i = 0; i < numIndices; i++) { indices.push_back(0); } // increases the vector size by 1// calculate triangle verticesfor (int i = 0; i <= prec; i++) {for (int j = 0; j <= prec; j++) {float y = (float)cos(toRadians(180.0f - i * 180.0f / prec));float x = -(float)cos(toRadians(j*360.0f / prec)) * (float)abs(cos(asin(y)));float z = (float)sin(toRadians(j*360.0f / prec)) * (float)abs(cos(asin(y)));vertices[i*(prec + 1) + j] = glm::vec3(x, y, z);texCoords[i*(prec + 1) + j] = glm::vec2(((float)j / prec), ((float)i / prec));normals[i*(prec + 1) + j] = glm::vec3(x, y, z);}}// calculate triangle indicesfor (int i = 0; i < prec; i++) {for (int j = 0; j < prec; j++) {indices[6 * (i*prec + j) + 0] = i * (prec + 1) + j;indices[6 * (i*prec + j) + 1] = i * (prec + 1) + j + 1;indices[6 * (i*prec + j) + 2] = (i + 1)*(prec + 1) + j;indices[6 * (i*prec + j) + 3] = i * (prec + 1) + j + 1;indices[6 * (i*prec + j) + 4] = (i + 1)*(prec + 1) + j + 1;indices[6 * (i*prec + j) + 5] = (i + 1)*(prec + 1) + j;}}
}
// accessors
int Sphere::getNumVertices() { return numVertices; }
int Sphere::getNumIndices() { return numIndices; }
std::vector<int> Sphere::getIndices() { return indices; }
std::vector<glm::vec3> Sphere::getVertices() { return vertices; }
std::vector<glm::vec2> Sphere::getTexCoords() { return texCoords; }
std::vector<glm::vec3> Sphere::getNormals() { return normals; }

6.1 Shpere.h

#pragma once
#include <cmath>
#include <vector>
#include <glm\glm.hpp>
class Sphere
{private:int numVertices;int numIndices;std::vector<int> indices;std::vector<glm::vec3> vertices;std::vector<glm::vec2> texCoords;std::vector<glm::vec3> normals;void init(int);float toRadians(float degrees);
public:Sphere();Sphere(int prec);int getNumVertices();int getNumIndices();std::vector<int> getIndices();std::vector<glm::vec3> getVertices();std::vector<glm::vec2> getTexCoords();std::vector<glm::vec3> getNormals();
};

5.2 Utils.cpp

#include "Utils/5.2 Utils.h"
#include "GL/glew.h"
#include "GLFW/glfw3.h"
#include "SOIL2/SOIL2.h"#include <iostream>
#include <string>
#include <fstream>
using namespace std;GLuint createShaderProgram(const char* a_Path, const char* b_Path) {GLint vertCompiled;GLint fragCompiled;GLint linked;string vertShaderStr = readShaderSource(a_Path); // 文件在add文件夹中string fragShaderStr = readShaderSource(b_Path);const char *vertShaderSrc = vertShaderStr.c_str();const char *fragShaderSrc = fragShaderStr.c_str();GLuint vShader = glCreateShader(GL_VERTEX_SHADER);GLuint fShader = glCreateShader(GL_FRAGMENT_SHADER);glShaderSource(vShader, 1, &vertShaderSrc, NULL);glShaderSource(fShader, 1, &fragShaderSrc, NULL);// 在编译着色器时，捕捉错误glCompileShader(vShader);checkOpenGLError();glGetShaderiv(vShader, GL_COMPILE_STATUS, &vertCompiled);if (vertCompiled != 1) {cout << "vertex compilation failed" << endl;printShaderLog(vShader);}glCompileShader(fShader);checkOpenGLError();glGetShaderiv(fShader, GL_COMPILE_STATUS, &fragCompiled);if (fragCompiled != 1) {cout << "fragment compilation failed" << endl;printShaderLog(fShader);}GLuint vfProgram = glCreateProgram();glAttachShader(vfProgram, vShader);glAttachShader(vfProgram, fShader);glLinkProgram(vfProgram);checkOpenGLError();glGetProgramiv(vfProgram, GL_LINK_STATUS, &linked);if (linked != 1) {cout << "linking failed" << endl;printProgramLog(vfProgram);}return vfProgram;
}string readShaderSource(const char *filePath) {string content;ifstream fileStream(filePath, ios::in);string line = "";while (!fileStream.eof()) {getline(fileStream, line);content.append(line + "\n");}fileStream.close();return content;
}
bool checkOpenGLError() {bool foundError = false;int glErr = glGetError();while (glErr != GL_NO_ERROR) {cout << "glError: " << glErr << endl;foundError = true;glErr = glGetError();}return foundError;
}void printProgramLog(int prog) {int len = 0;int chWrittn = 0;char *log;glGetProgramiv(prog, GL_INFO_LOG_LENGTH, &len);if (len > 0) {log = (char *)malloc(len);glGetProgramInfoLog(prog, len, &chWrittn, log);cout << "Program Info Log: " << log << endl;free(log);}
}
void printShaderLog(GLuint shader) {int len = 0;int chWrittn = 0;char *log;glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &len);if (len > 0) {log = (char *)malloc(len);glGetShaderInfoLog(shader, len, &chWrittn, log);cout << "Shader Info Log: " << log << endl;free(log);}
}GLuint loadTexture(const char *texImagePath) {GLuint textureID;textureID = SOIL_load_OGL_texture(texImagePath,SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_INVERT_Y);if (textureID == 0) cout << "could not find texture file" << texImagePath << endl;// mipmapsglBindTexture(GL_TEXTURE_2D, textureID); 不倒置也不镜像——多选一//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); 倒置+镜像——多选一//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT);//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT); 仅有一个，其余颜色为红色——多选一//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);//glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);//float redColor[4] = { 1.0f, 0.0f, 0.0f, 1.0f };//glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, redColor);// 仅有一个，其余为图片最边缘一行一列的颜色拓展——多选一glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);glGenerateMipmap(GL_TEXTURE_2D);// if also anisotropic filtering if (glewIsSupported("GL_EXT_texture_filter_anisotropic")) {GLfloat anisoSetting = 0.0f;glGetFloatv(GL_MAX_TEXTURE_MAX_ANISOTROPY_EXT, &anisoSetting);//glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAX_ANISOTROPY_EXT, anisoSetting);}return textureID;
}

5.2 Utils.h

#pragma once
#ifndef UTILS_H
#define UTILS_H
#include <string>
#include "GL\glew.h"
#include "GLFW\glfw3.h"
using namespace std;GLuint createShaderProgram(const char* a_Path, const char* b_Path);
string readShaderSource(const char *filePath);
bool checkOpenGLError();
void printProgramLog(int prog);
void printShaderLog(GLuint shader);
GLuint loadTexture(const char *texImagePath);#endif // !UTILS_H

5.2 vertShader.glsl

#version 430
layout (location=0) in vec3 pos;
layout (location=1) in vec2 texCoord;
out vec2 tc; // texture coordinate output to rasterizer for interpolation
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
layout (binding=0) uniform sampler2D samp; // not used in vertex shader
void main(void)
{    gl_Position = proj_matrix * mv_matrix * vec4(pos,1.0);tc = texCoord;
}

5.2 fragShader.glsl

#version 430
in vec2 tc; // interpolated incoming texture coordinate
out vec4 color;
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
layout (binding=0) uniform sampler2D samp;
void main(void)
{ color = texture(samp, tc);
}

brick1.jpg

6.1 earth.jpg

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生成

完整代码

220301 6.1 Sphere.cpp

6.1 Shpere.cpp

6.1 Shpere.h

5.2 Utils.cpp

5.2 Utils.h

5.2 vertShader.glsl

5.2 fragShader.glsl

brick1.jpg

6.1 earth.jpg

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