原图片:
1.左右镜像变换
这里总结下左右颠倒的方法:
就是更改片段着色器
FragColor = mix(texture(texture1,TexCoord), texture(texture2,vec2(1.0 - TexCoord.x, TexCoord.y)),0.78f);
这段代码的意思就是更改图片的纹理坐标
比如:
(0,0) -> (1,0)
(1,0) -> (0,0)
(0,1) -> (1,1)
(1,1) -> (0,1)
2.
- 尝试用不同的纹理环绕方式，设定一个从
0.0f到2.0f范围内的（而不是原来的0.0f到1.0f）纹理坐标。试试看能不能在箱子的角落放置4个笑脸：，。记得一定要试试其它的环绕方式。
把笑脸的环绕方式改为 GL_MIRRORED_REPEAT
然后纹理坐标更改:
变为
(这时候超出的边界会自动填充重复的图象)
3.只显示一部分图象,然后用线性放大
4.使用方向键更改图象透明度
额外设置一个uniform maxValue就可以了
键盘输入
镜像翻转示范代码(库请自己看教程寻找):
OpenGLDemo.cpp
// OpenGLDemo.cpp: 定义控制台应用程序的入口点。#include "stdafx.h"#include#include #include #include #include #include #include #include #include "Shader.h"#include #include using namespace std;void framebuffer_size_callback(GLFWwindow* window, int width, int height);void processInput(GLFWwindow* window);char* readTheFile(string strSource);int main(){ //glfw: 初始化 glfwInit(); glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR,3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR,3); glfwWindowHint(GLFW_OPENGL_PROFILE,GLFW_OPENGL_CORE_PROFILE); //glfw: 窗口创建 GLFWwindow* window = glfwCreateWindow(800, 600, "Oh!I see you!", NULL, NULL); if (window == NULL) { std::cout << "Failed to create the windows" << std::endl; glfwTerminate(); return -1; } glfwMakeContextCurrent(window); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); glfwSwapInterval(1); //glad: 加载OpenGL 函数指针 if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) { std::cout << "Failed to initialize GLAD" << std::endl; return -1; } Shader shader("vertexShaderSource.vert", "fragmentShaderSource.frag"); float vertices[] = { //第一个三角形 // ----位置---- ----颜色---- --纹理坐标- -.5f,.5f,0.0f, 1.0f,0.0f,0.0f, 0.0f,1.0f, //左上 -.5f,-.5f,.0f, 0.0f,1.0f,0.0f, 0.0f,0.0f, //左下 .5f,-.5f,.0f, 0.0f,0.0f,1.0f, 1.0f,0.0f, //右下 .5f, .5f,.0f, 0.0f,0.0f,1.0f, 1.0f,1.0f //右上 }; unsigned int indices[] = { 0,1,2, 0,3,2 }; unsigned int VBO, VAO, EBO; glGenVertexArrays(1, &VAO); glGenBuffers(1, &VBO); glGenBuffers(1, &EBO); //绑定顶点数组 glBindVertexArray(VAO); glBindBuffer(GL_ARRAY_BUFFER, VBO); glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO); glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW); //指针分配 glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0); glEnableVertexAttribArray(0); glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float))); glEnableVertexAttribArray(1); glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float))); glEnableVertexAttribArray(2); //texture 1 //--------- unsigned int texture1,texture2; glGenTextures(1, &texture1); glBindTexture(GL_TEXTURE_2D, texture1); 为当前绑定的纹理对象设置环绕、过滤方式 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT); float borderColor[] = { 1.0f,1.0f,0.0f,1.0f }; glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); //加载纹理图片 int width, height, nrChannels; unsigned char *data = stbi_load("container.jpg", &width, &height, &nrChannels, 0); if (data) {//生成纹理图片 glTexImage2D(GL_TEXTURE_2D,0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout << "Failed to load texture" << std::endl; } //释放内存 stbi_image_free(data); //texture 2 //--------- glGenTextures(1, &texture2); glBindTexture(GL_TEXTURE_2D, texture2); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); stbi_set_flip_vertically_on_load(true); data = stbi_load("LJW.png", &width, &height, &nrChannels, 0); if (data) { glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data); glGenerateMipmap(GL_TEXTURE_2D); } else { std::cout << "Failed to load texture" << std::endl; } stbi_image_free(data); shader.use(); shader.setInt("texture1", 0); shader.setInt("texture2", 1); while (!glfwWindowShouldClose(window)) { //输入处理 processInput(window); //渲染指令 glClearColor(0.2f,0.3f,0.3f,1.0f); glClear(GL_COLOR_BUFFER_BIT); glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture1); glActiveTexture(GL_TEXTURE1); glBindTexture(GL_TEXTURE_2D, texture2); shader.use(); glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT , 0); glBindVertexArray(VAO); glDrawArrays(GL_TRIANGLES,0,3); glfwSwapBuffers(window); glfwPollEvents(); } glfwTerminate(); return 0;}void framebuffer_size_callback(GLFWwindow* windows, int width, int height) { glViewport(0, 0, width, height);}void processInput(GLFWwindow* window) { if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS) { glfwSetWindowShouldClose(window, true); }}//.frag .vert文件读取char* readTheFile(string strSource) { //fstream 中判断是否成功打开文件 //https://blog.csdn.net/fruitz/article/details/41624921 std::ifstream myfile(strSource); //打开失败 if (myfile.fail()) { std::cout << "Can not open it " << std::endl; throw new runtime_error("IO stream corrupted"); } //转换成字符串 std::string str((std::istreambuf_iterator (myfile)), std::istreambuf_iterator ()); //关闭文件处理器 myfile.close(); //str数组长度一定要 +1, /*原因: https://blog.csdn.net/ShiQW5696/article/details/80676290 */ int len = str.length(); char* result = new char[len]; strcpy_s(result, len + 1, str.c_str()); return result;}
fragmentShaderSource.frag
#version 330 coreout vec4 FragColor;in vec2 TexCoord;in vec3 outColor;uniform sampler2D texture1;uniform sampler2D texture2;void main(){ FragColor = mix(texture(texture1,TexCoord), texture(texture2,vec2(1.0 - TexCoord.x, TexCoord.y)),0.78f);}
vertexShaderSource.vert
#version 330 corelayout(location = 0) in vec3 aPos;layout(location = 1) in vec3 aColor;layout(location = 2) in vec2 aTexCoord;out vec3 outColor;out vec2 TexCoord;void main(){ gl_Position = vec4(aPos, 1.0); outColor = aColor; TexCoord = aTexCoord;}