准备第三方库 glew、freeglut、glm、opencv
准备一张灰度图
最终效果
代码如下
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <GL/glew.h>
#include <GL/freeglut.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
using namespace std;
using namespace cv;
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
GLuint UVBO;//uv缓冲对象
GLuint TexBO;//贴图对象
GLuint NormalBO;//法线对象
//光照定义
struct {
GLuint Color;//颜色
GLuint AmbientIntensity;//环境光强度
GLuint Direction;//方向
GLuint DiffuseIntensity;//漫反射强度
} m_dirLightLocation;
static GLfloat *vertices;
static unsigned int *indices;
static GLfloat *uvs;
static GLfloat *normals;
GLuint ShaderProgram;
GLuint MatrixID;
GLuint MatrixID2;
GLuint TextureID;
int windowWidth = 1000;
int windowHeight = 800;
int imgWidth;
int imgHeihgt;
float verticeScale = 0.1f;
float yScale = 5.0f;
//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 = 0.005f;
int mouseX, mouseY;//鼠标位置 窗口坐标
bool mouseLeftDown = false;//鼠标左键按下
// 传递键盘事件
static void SpecialKeyboardCB(unsigned char 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 'w':
position += direction * speed;
//fprintf(stderr, "up
");
break;
case 'd':
position += right * speed;
//fprintf(stderr, "right
");
break;
case 's':
position -= direction * speed;
//fprintf(stderr, "down
");
break;
case 'a':
position -= right * speed;
//fprintf(stderr, "left
");
break;
case 27:
exit(1);
break;
default:
break;
//fprintf(stderr, "Unimplemented GLUT key
");
//exit(1);
}
float FoV = initialFoV;
ProjectionMatrix = glm::perspective(glm::radians(FoV), (float)windowWidth / (float)windowHeight, 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
void mouseCB(int button, int state, int x, int y)
{
if (button == GLUT_LEFT_BUTTON)
{
if (state == GLUT_DOWN)
{
mouseLeftDown = true;
mouseX = x;
mouseY = y;
}
else if (state == GLUT_UP)
{
mouseLeftDown = false;
}
}
}
//传递鼠标位置
static void mouseMotionCB(int x, int y)
{
if (mouseLeftDown == true)
{
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
//传递矩阵数据
glUniformMatrix4fv(MatrixID, 1, GL_FALSE, &MVP[0][0]);
glUniformMatrix4fv(MatrixID2,1, GL_FALSE,&ModelMatrix[0][0]);
//传递光照
glUniform3f(m_dirLightLocation.Color, 1, 1, 0);
glUniform1f(m_dirLightLocation.AmbientIntensity, 0.5);
glUniform3f(m_dirLightLocation.Direction,1,1,0);
glUniform1f(m_dirLightLocation.DiffuseIntensity,0.7);
//传递顶点、索引、UV、法线
glEnableVertexAttribArray(0); //开启顶点属性
glBindBuffer(GL_ARRAY_BUFFER, VBO); //绑定GL_ARRAY_BUFFER缓冲器
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0); //告诉管线怎样解析bufer中的数据
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO);
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, UVBO);
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(2);
glBindBuffer(GL_ARRAY_BUFFER, NormalBO);
glVertexAttribPointer(2, 3, GL_FLOAT, GL_FALSE, 0, 0);
//传递贴图纹理
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, TexBO);
glUniform1i(TextureID, 0);
//绘制
glDrawElements(GL_TRIANGLES_ADJACENCY, (imgWidth - 1)*(imgHeihgt - 1) * 6 * 4, GL_UNSIGNED_SHORT, 0);
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
glDisableVertexAttribArray(2);
//交换前后缓存
glutSwapBuffers();
}
//创建顶点
static void CreateVertexBuffer()
{
//读取图片
Mat img = imread("T2.png");
int imgType = img.type();
Mat resImg = Mat(img.rows, img.cols, imgType);
resize(img, resImg, resImg.size(), 0, 0, INTER_LINEAR);
Mat gImg = Mat(img.rows, img.cols, CV_8UC1); //灰度图
cv::cvtColor(resImg, gImg, CV_BGR2GRAY);//bgr转灰度
imgWidth = resImg.rows;
imgHeihgt = resImg.cols;
vertices = new GLfloat[imgWidth*imgHeihgt * 3];
int k = 0;
for (int i = 0; i < imgHeihgt; i++)
{
for (int j = 0; j < imgWidth; j++)
{
vertices[k++] = verticeScale* (float)i;
int c = (int)gImg.at<uchar>(j, i);
vertices[k++] = yScale*(float)c / 255.0f;
vertices[k++] = verticeScale*(float)j;
}
}
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, imgWidth*imgHeihgt * 3 * sizeof(GLfloat), vertices, GL_STATIC_DRAW);
}
//创建索引
static void CreateIndexBuffer()
{
indices = new unsigned int[(imgWidth - 1)*(imgHeihgt - 1) * 6];
int k = 0;
for (int i = 0; i < imgHeihgt - 1; i++)
{
for (int j = 0; j < imgWidth - 1; j++)
{
indices[k++] = i*imgWidth + j;
indices[k++] = i*imgWidth + j + 1;
indices[k++] = i*imgWidth + j + imgWidth;
indices[k++] = i*imgWidth + j + imgWidth;
indices[k++] = i*imgWidth + j + 1;
indices[k++] = i*imgWidth + j + imgWidth + 1;
}
}
glGenBuffers(1, &IBO);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, IBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, (imgWidth - 1)*(imgHeihgt - 1) * 6 * sizeof(unsigned int), indices, GL_STATIC_DRAW);
}
//创建uv
static void CreateUVBuffer()
{
uvs = new GLfloat[imgWidth*imgHeihgt * 2];
int k = 0;
for (int i = 0; i < imgHeihgt; i++)
{
for (int j = 0; j < imgWidth; j++)
{
uvs[k++] = (float)i / (float)(imgHeihgt);
uvs[k++] = (float)j / (float)(imgWidth);
}
}
glGenBuffers(1, &UVBO);
glBindBuffer(GL_ARRAY_BUFFER, UVBO);
glBufferData(GL_ARRAY_BUFFER, imgWidth*imgHeihgt * 2 * sizeof(GLfloat), uvs, GL_STATIC_DRAW);
}
//创建贴图
static void CreateTexture()
{
Mat img = imread("T2.png");
Mat resImg = Mat(256, 256, img.type());
resize(img, resImg, resImg.size(), 0, 0, INTER_LINEAR);
cv::cvtColor(resImg, resImg, CV_BGR2RGB);
glGenTextures(1, &TexBO);
glBindTexture(GL_TEXTURE_2D, TexBO);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 256, 256, 0, GL_RGB, GL_UNSIGNED_BYTE, resImg.data);//设定纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);//重复纹理
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);//滤波
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 1);
glGenerateMipmap(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, 0);
TextureID = glGetUniformLocation(ShaderProgram, "myTexture");
}
//创建法线
static void CreateNormal()
{
normals= new GLfloat[imgWidth*imgHeihgt*3];
int k = 0;
//遍历索引三角
for (size_t i = 0; i < (imgWidth - 1)*(imgHeihgt - 1) * 6; i+=3)
{
static unsigned int pIndex1 = indices[i];
static unsigned int pIndex2 = indices[i + 1];
static unsigned int pIndex3 = indices[i + 2];
static float x1 = vertices[pIndex1];
static float y1 = vertices[pIndex1 + 1];
static float z1 = vertices[pIndex1 + 2];
static float x2 = vertices[pIndex2];
static float y2 = vertices[pIndex2 + 1];
static float z2 = vertices[pIndex2 + 2];
static float x3 = vertices[pIndex3];
static float y3 = vertices[pIndex3 + 1];
static float z3 = vertices[pIndex3 + 2];
//求边
static float vx1 = x2 - x1;
static float vy1 = y2 - y1;
static float vz1 = z2 - z1;
static float vx2 = x3 - x1;
static float vy2 = y3 - y1;
static float vz2 = z3 - z1;
//叉乘求三角形法线
static float xN = vy1 * vz2 - vz1 *vy2;
static float yN = vz1 * vx2 - vx1 * vz2;
static float zN = vx1 * vy2 - vy1 * vx2;
static float Length = sqrtf(xN * xN + yN * yN + zN * zN);
xN /= Length;
yN /= Length;
zN /= Length;
//顶点法线更新
normals[pIndex1] += xN;
normals[pIndex1 + 1] += yN;
normals[pIndex1 + 2] += zN;
normals[pIndex2] += xN;
normals[pIndex2 + 1] += yN;
normals[pIndex2 + 2] += zN;
normals[pIndex3] += xN;
normals[pIndex3 + 1] += yN;
normals[pIndex3 + 2] += zN;
}
glGenBuffers(1, &NormalBO);
glBindBuffer(GL_ARRAY_BUFFER, NormalBO);
glBufferData(GL_ARRAY_BUFFER, imgWidth*imgHeihgt * 3 * sizeof(GLfloat), normals, 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
", 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'
", 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
");
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
", 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'
", 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'
", ErrorLog);
exit(1);
}
glUseProgram(ShaderProgram);
//统一变量位置
MatrixID = glGetUniformLocation(ShaderProgram, "gWVP");
MatrixID2= glGetUniformLocation(ShaderProgram, "gWorld");
m_dirLightLocation.Color = glGetUniformLocation(ShaderProgram,"gDirectionalLight.Color");
m_dirLightLocation.AmbientIntensity = glGetUniformLocation(ShaderProgram,"gDirectionalLight.AmbientIntensity");
m_dirLightLocation.Direction = glGetUniformLocation(ShaderProgram,"gDirectionalLight.Direction");
m_dirLightLocation.DiffuseIntensity = glGetUniformLocation(ShaderProgram,"gDirectionalLight.DiffuseIntensity");
}
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);
// 窗口设置
glutInitWindowSize(windowWidth, windowHeight); // 窗口尺寸
glutInitWindowPosition(100, 100); // 窗口位置
glutCreateWindow("terrainTest2"); // 窗口标题
GLenum res = glewInit();
if (res != GLEW_OK) {
fprintf(stderr, "Error: '%s'
", glewGetErrorString(res));
return 1;
}
// 开始渲染
glutDisplayFunc(RenderScenceCB);
// 注册键盘事件
glutKeyboardFunc(SpecialKeyboardCB);
//注册鼠标事件
glutMouseFunc(mouseCB);
glutMotionFunc(mouseMotionCB);
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();
//创建uv
CreateUVBuffer();
//创建贴图
CreateTexture();
//创建法线
CreateNormal();
// 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;
}
#version 330
layout (location = 0) in vec3 Position;
layout (location = 1) in vec2 vertexUV;
layout (location = 2) in vec3 Normal;
uniform mat4 gWVP;
uniform mat4 gWorld;
out vec2 UV;
out vec3 Normal0;
void main()
{
gl_Position = gWVP * vec4(Position, 1.0);
UV = vertexUV;
Normal0 = (gWorld * vec4(Normal, 0.0)).xyz;
}
#version 330
in vec2 UV;
in vec3 Normal0;
out vec4 FragColor;
//光照
struct DirectionalLight
{
vec3 Color;
float AmbientIntensity;
float DiffuseIntensity;
vec3 Direction;
};
uniform DirectionalLight gDirectionalLight;
uniform sampler2D myTexture;
void main()
{
//环境光
vec4 AmbientColor = vec4(gDirectionalLight.Color, 1.0f) *
gDirectionalLight.AmbientIntensity;
//漫反射
float DiffuseFactor = dot(normalize(Normal0), -gDirectionalLight.Direction);
vec4 DiffuseColor;
if (DiffuseFactor > 0) {
DiffuseColor = vec4(gDirectionalLight.Color, 1.0f) *
gDirectionalLight.DiffuseIntensity *
DiffuseFactor;
}
else {
DiffuseColor = vec4(0, 0, 0, 0);
}
FragColor = texture2D(myTexture, UV.xy) *
(AmbientColor + DiffuseColor);
}