新北网站建设,滨州五学一做考试网站,青羊区网站设计,京东网站的建设与发展现状引言 这是一个闪耀的时刻#xff0c;因为我们即将能生产出令人惊叹的3D效果#xff01;
变换 向量和矩阵变换包括太多内容#xff0c;但由于学过线性代数和GAMES101#xff0c;因此不在此做过多阐述。仅阐述包括代码的GLM内容。
GLM的使用
#xff08;1#xff09;GLM…引言 这是一个闪耀的时刻因为我们即将能生产出令人惊叹的3D效果
变换 向量和矩阵变换包括太多内容但由于学过线性代数和GAMES101因此不在此做过多阐述。仅阐述包括代码的GLM内容。
GLM的使用
1GLM的配置 GLM是OpenGL Mathematics的缩写它是一个只有头文件的库也就是说我们只需包含对应的头文件就行了不用链接和编译。GLM可以在它们的网站上下载。把头文件的根目录复制到你的includes文件夹然后你就可以使用这个库了。 我们需要的GLM的大多数功能都可以从下面这3个头文件中找到
#include glm/glm.hpp
#include glm/gtc/matrix_transform.hpp
#include glm/gtc/type_ptr.hpp2GLM中类型的使用 例子1定义向量100并使其位移110。注意需要把他定义为一个glm::vec4类型的值并且其次坐标设定为1.0。 // 使用glm::vec4定义一个四维向量齐次坐标为1.0glm::vec4 vec(1.0f, 0.0f, 0.0f, 1.0f);// 使用glm::mat4定义一个4x4的矩阵// glm::mat4如果不初始化则数据会是未知的所以用以下方式初始化为单位矩阵glm::mat4 trans glm::mat4(1.0f);// 使用glm::translate(变换矩阵,位移向量)// glm::translate返回变换矩阵添加位移效果后得到的矩阵trans glm::translate(trans, glm::vec3(1.0f, 1.0f, 0.0f));// 使用 变换矩阵✖四维向量 变换后的向量vec trans * vec;std::cout vec.x vec.y vec.z std::endl;例子2我们来旋转和缩放之前教程中的那个箱子。首先我们把箱子逆时针旋转90度。然后缩放0.5倍使它变成原来的一半大。我们来创建变换矩阵 glm::mat4 trans;trans glm::rotate(trans, 90.0f, glm::vec3(0.0, 0, 1.0));trans glm::scale(trans, glm::vec3(0.5, 0.5, 0.5));针对变换顺序的讨论 绝大多数情况下我们约定的变换顺序是先缩放再旋转最后平移。这样变换顺序的依据是比如我们Blender里面建模了一个可乐罐我们要将它从自己的局部坐标转换到世界坐标比如我们希望它位移到桌子上、倾斜45°、x和y轴均匀缩放至0.5倍。我们可以试想如果先将可乐瓶倾斜45°再缩放的话原本针对x轴和y轴的缩放应将可乐瓶的半径和高进行缩放至一半但是现在可乐瓶倾斜了导致缩放不是针对可乐瓶的半径和高了即可乐瓶的半径不在x轴上高不在y轴上由此我们得出结论缩放要在旋转之前进行因为我们潜意识里的缩放就是针对模型未旋转时体态的缩放。还有一个很重要的事情是我们推导旋转矩阵是基于旋转中心在原点时因此我们使用旋转矩阵务必要保证旋转中心在原点试想我们从Blender中建模的对象其所在局部坐标一定旋转中心是在原点的但是当我们对他进行平移之后它的几何中心就不在原点了。因此我们的旋转应该是针对物体最初的位置进行的所以我们得到结论旋转需要在位移之前。综上所述我们就明白了需要先缩放、再旋转、最后位移。 设变换矩阵初始为M0单位矩阵,设我们需要变换的坐标为 ve4,设我们需要对ve4做的一系列顺序变换为(S1,S2,S3)设这一系列变换对应的变换矩阵为(M1,M2,M3)。则我们应该做的是M3✖M2✖M1✖ve4这样我们则对ve4按顺序执行了变换。那么如果我们要使用一个变换矩阵M包含所有的变换怎么办呢 由于矩阵乘法满足结合律即A✖B✖C(A✖B)✖CA✖(B✖C)。因此M3✖M2✖M1✖ve4(M3✖M2✖M1)✖ve4M(M3✖M2✖M1)。我们要先计M3再乘M2再乘M1即可得到M变换矩阵。而对于平移旋转缩放而言优先级为平移旋转缩放所以应算平移矩阵、再旋转、再计算缩放。如此就可以解释上文中对图形先缩放再旋转的变化顺序也可以解释代码中先对变化矩阵进行了旋转再对变换矩阵进行了缩放。 如果在后续程序中你的笑脸旋转了但是不是正确你预料之中的角度那么可能是下图的问题。如果你不对你程序中的glm::mat4对象初始化可能你就看不到你的笑脸了。 顶点着色器
// 声明OpenGL版本
#version 330 core
// 定义包含位置值的输入变量
layout (location 0) in vec3 position; // 顶点位置
layout (location 1) in vec3 color; // 顶点颜色
layout (location 2) in vec3 textCoord; // 顶点的纹理坐标
// 定义输出变量到片段着色器
out vec3 ourColor; // 顶点颜色
out vec2 TexCoord; // 顶点的纹理坐标uniform mat4 transform; // 变换矩阵void main()
{// 使用变换矩阵左乘顶点位置得到变换后位置并赋值gl_Position transform * vec4(position, 1.0f);// 将顶点颜色输出给片段着色器ourColor color;// 顶点的纹理坐标由于图片是反的所以纹理坐标的y值“取反”TexCoord vec2(texCoord.x , 1.0 - texCoord.y);
} 我们现在需要把变换矩阵传递给着色器
#version 330 core
in vec3 ourColor;
in vec2 TexCoord;out vec4 color;uniform float mixValue;// Texture samplers
uniform sampler2D ourTexture1;
uniform sampler2D ourTexture2;void main()
{// Linearly interpolate between both textures (second texture is only slightly combined)color mix(texture(ourTexture1, TexCoord), texture(ourTexture2, TexCoord), mixValue);
}GLuint transformLoc glGetUniformLocation(ourShader.Program,transform);
glUniformMatrix4v(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));最终效果 完整代码
#include iostream// GLEW
#define GLEW_STATIC
#include GL/glew.h// GLFW
#include GLFW/glfw3.h// Other Libs
#include SOIL.H// Other includes
#include Shader.h#include glm/glm.hpp
#include glm/gtc/matrix_transform.hpp
#include glm/gtc/type_ptr.hpp// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);// Window dimensions
const GLuint WIDTH 800, HEIGHT 600;GLfloat mixValue 0.2f;// The MAIN function, from here we start the application and run the game loop
int main()
{glm::mat4 trans glm::mat4(1.0f);trans glm::rotate(trans,glm::radians(90.0f), glm::vec3(0.0, 0, 1.0));trans glm::scale(trans, glm::vec3(0.5, 0.5, 0.5));// Init GLFWglfwInit();// Set all the required options for GLFWglfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);// Create a GLFWwindow object that we can use for GLFWs functionsGLFWwindow* window glfwCreateWindow(WIDTH, HEIGHT, LearnOpenGL, nullptr, nullptr);glfwMakeContextCurrent(window);// Set the required callback functionsglfwSetKeyCallback(window, key_callback);// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensionsglewExperimental GL_TRUE;// Initialize GLEW to setup the OpenGL Function pointersglewInit();// Define the viewport dimensionsglViewport(0, 0, WIDTH, HEIGHT);// Build and compile our shader programShader ourShader(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Shader\\vertexShader.txt, C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Shader\\fragmentShader.txt);// Set up vertex data (and buffer(s)) and attribute pointersGLfloat vertices[] {// Positions // Colors // Texture Coords0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // Top Right0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Bottom Right-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // Bottom Left-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // Top Left };GLuint indices[] { // Note that we start from 0!0, 1, 3, // First Triangle1, 2, 3 // Second Triangle};GLuint VBO, VAO, EBO;glGenVertexArrays(1, VAO);glGenBuffers(1, VBO);glGenBuffers(1, EBO);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);// Position attributeglVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);glEnableVertexAttribArray(0);// Color attributeglVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));glEnableVertexAttribArray(1);// TexCoord attributeglVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));glEnableVertexAttribArray(2);glBindVertexArray(0); // Unbind VAO// Load and create a texture GLuint texture1;GLuint texture2;// // Texture 1// glGenTextures(1, texture1);glBindTexture(GL_TEXTURE_2D, texture1); // All upcoming GL_TEXTURE_2D operations now have effect on our texture object// Set our texture parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // Set texture wrapping to GL_REPEATglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);// Set texture filteringglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);// Load, create texture and generate mipmapsint width, height;unsigned char* image SOIL_load_image(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Resource\\container.jpg, width, height, 0, SOIL_LOAD_RGB);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);glBindTexture(GL_TEXTURE_2D, 0); // Unbind texture when done, so we wont accidentily mess up our texture.// // Texture 2// glGenTextures(1, texture2);glBindTexture(GL_TEXTURE_2D, texture2);// Set our texture parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);float borderColor[] { 1.0f, 1.0f , 0.0f, 1.0f };glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);// Set texture filteringglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);// Load, create texture and generate mipmapsimage SOIL_load_image(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Resource\\awesomeface.png, width, height, 0, SOIL_LOAD_RGB);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);glBindTexture(GL_TEXTURE_2D, 0);// Game loopwhile (!glfwWindowShouldClose(window)){// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functionsglfwPollEvents();// Render// Clear the colorbufferglClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);// Activate shaderourShader.Use();// Bind Textures using texture unitsglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, texture1);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture1), 0);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, texture2);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture2), 1);GLuint transformLoc glGetUniformLocation(ourShader.Program, transform);glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));// 设置混合参数glUniform1f(glGetUniformLocation(ourShader.Program,mixValue),mixValue);// Draw containerglBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);glBindVertexArray(0);// Swap the screen buffersglfwSwapBuffers(window);}// Properly de-allocate all resources once theyve outlived their purposeglDeleteVertexArrays(1, VAO);glDeleteBuffers(1, VBO);glDeleteBuffers(1, EBO);// Terminate GLFW, clearing any resources allocated by GLFW.glfwTerminate();return 0;
}// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{if (key GLFW_KEY_ESCAPE action GLFW_PRESS)glfwSetWindowShouldClose(window, GL_TRUE);if (key GLFW_KEY_UP action GLFW_PRESS){mixValue 0.1f;if (mixValue 1.0f)mixValue 1.0f;}if (key GLFW_KEY_DOWN action GLFW_PRESS){mixValue - 0.1f;if (mixValue 0.0f)mixValue 0.0f;}
}3随时间旋转的笑脸 我们可以定义一个无限数量的变换把它们组合为仅仅一个矩阵如果愿意的话我们还可以重复使用它。在着色器中使用矩阵可以省去重新定义顶点数据的功夫它也能够节省处理时间因为我们没有一直重新发送我们的数据这是个非常慢的过程。 上文中的旋转还是很呆因为是一个不会动的旋转后笑脸。所以我们现在打算让他动起来即旋转角度会根据时间变换生成变换矩阵即可。 效果 代码如下
glm::mat4 trans;
trans glm::translate(trans, glm::vec3(0.5f, -0.5f, 0.0f));
trans glm::rotate(trans,(GLfloat)glfwGetTime() * 50.0f, glm::vec3(0.0f, 0.0f, 1.0f));完整代码
#include iostream// GLEW
#define GLEW_STATIC
#include GL/glew.h// GLFW
#include GLFW/glfw3.h// Other Libs
#include SOIL.H// Other includes
#include Shader.h#include glm/glm.hpp
#include glm/gtc/matrix_transform.hpp
#include glm/gtc/type_ptr.hpp// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);// Window dimensions
const GLuint WIDTH 800, HEIGHT 600;GLfloat mixValue 0.2f;// The MAIN function, from here we start the application and run the game loop
int main()
{// Init GLFWglfwInit();// Set all the required options for GLFWglfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);// Create a GLFWwindow object that we can use for GLFWs functionsGLFWwindow* window glfwCreateWindow(WIDTH, HEIGHT, LearnOpenGL, nullptr, nullptr);glfwMakeContextCurrent(window);// Set the required callback functionsglfwSetKeyCallback(window, key_callback);// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensionsglewExperimental GL_TRUE;// Initialize GLEW to setup the OpenGL Function pointersglewInit();// Define the viewport dimensionsglViewport(0, 0, WIDTH, HEIGHT);// Build and compile our shader programShader ourShader(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Shader\\vertexShader.txt, C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Shader\\fragmentShader.txt);// Set up vertex data (and buffer(s)) and attribute pointersGLfloat vertices[] {// Positions // Colors // Texture Coords0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // Top Right0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Bottom Right-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // Bottom Left-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // Top Left };GLuint indices[] { // Note that we start from 0!0, 1, 3, // First Triangle1, 2, 3 // Second Triangle};GLuint VBO, VAO, EBO;glGenVertexArrays(1, VAO);glGenBuffers(1, VBO);glGenBuffers(1, EBO);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);// Position attributeglVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);glEnableVertexAttribArray(0);// Color attributeglVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));glEnableVertexAttribArray(1);// TexCoord attributeglVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));glEnableVertexAttribArray(2);glBindVertexArray(0); // Unbind VAO// Load and create a texture GLuint texture1;GLuint texture2;// // Texture 1// glGenTextures(1, texture1);glBindTexture(GL_TEXTURE_2D, texture1); // All upcoming GL_TEXTURE_2D operations now have effect on our texture object// Set our texture parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // Set texture wrapping to GL_REPEATglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);// Set texture filteringglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);// Load, create texture and generate mipmapsint width, height;unsigned char* image SOIL_load_image(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Resource\\container.jpg, width, height, 0, SOIL_LOAD_RGB);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);glBindTexture(GL_TEXTURE_2D, 0); // Unbind texture when done, so we wont accidentily mess up our texture.// // Texture 2// glGenTextures(1, texture2);glBindTexture(GL_TEXTURE_2D, texture2);// Set our texture parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);float borderColor[] { 1.0f, 1.0f , 0.0f, 1.0f };glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);// Set texture filteringglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);// Load, create texture and generate mipmapsimage SOIL_load_image(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Resource\\awesomeface.png, width, height, 0, SOIL_LOAD_RGB);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);glBindTexture(GL_TEXTURE_2D, 0);// Game loopwhile (!glfwWindowShouldClose(window)){// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functionsglfwPollEvents();// Render// Clear the colorbufferglClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);// Activate shaderourShader.Use();glm::mat4 trans glm::mat4(1.0f);trans glm::rotate(trans, glm::radians((GLfloat)glfwGetTime()*50.0f), glm::vec3(0.0, 0, 1.0));trans glm::scale(trans, glm::vec3(0.5, 0.5, 0.5));// Bind Textures using texture unitsglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, texture1);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture1), 0);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, texture2);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture2), 1);GLuint transformLoc glGetUniformLocation(ourShader.Program, transform);glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));// 设置混合参数glUniform1f(glGetUniformLocation(ourShader.Program,mixValue),mixValue);// Draw containerglBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);glBindVertexArray(0);// Swap the screen buffersglfwSwapBuffers(window);}// Properly de-allocate all resources once theyve outlived their purposeglDeleteVertexArrays(1, VAO);glDeleteBuffers(1, VBO);glDeleteBuffers(1, EBO);// Terminate GLFW, clearing any resources allocated by GLFW.glfwTerminate();return 0;
}// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{if (key GLFW_KEY_ESCAPE action GLFW_PRESS)glfwSetWindowShouldClose(window, GL_TRUE);if (key GLFW_KEY_UP action GLFW_PRESS){mixValue 0.1f;if (mixValue 1.0f)mixValue 1.0f;}if (key GLFW_KEY_DOWN action GLFW_PRESS){mixValue - 0.1f;if (mixValue 0.0f)mixValue 0.0f;}
}变换的练习
练习一 使用应用在箱子上的最后一个变换尝试将其改变为先旋转后位移。看看发生了什么试着想想为什么会发生这样的事情。 诸如我们上文所说旋转矩阵的运算是针对旋转中心在原点的代码中先将矩阵旋转再位移相当于对矩阵先位移再旋转。这时会发现笑脸绕着窗口中心原点不停的逆时针旋转。这是由于旋转中心的不同导致的差距。当先进行移动后笑脸的几何中心就不在原点了原本打算让它绕着几何中心旋转变成了绕着原点非几何中心旋转。 结果 源代码
#include iostream// GLEW
#define GLEW_STATIC
#include GL/glew.h// GLFW
#include GLFW/glfw3.h// Other Libs
#include SOIL.H// Other includes
#include Shader.h#include glm/glm.hpp
#include glm/gtc/matrix_transform.hpp
#include glm/gtc/type_ptr.hpp// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);// Window dimensions
const GLuint WIDTH 800, HEIGHT 600;GLfloat mixValue 0.2f;// The MAIN function, from here we start the application and run the game loop
int main()
{// Init GLFWglfwInit();// Set all the required options for GLFWglfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);// Create a GLFWwindow object that we can use for GLFWs functionsGLFWwindow* window glfwCreateWindow(WIDTH, HEIGHT, LearnOpenGL, nullptr, nullptr);glfwMakeContextCurrent(window);// Set the required callback functionsglfwSetKeyCallback(window, key_callback);// Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensionsglewExperimental GL_TRUE;// Initialize GLEW to setup the OpenGL Function pointersglewInit();// Define the viewport dimensionsglViewport(0, 0, WIDTH, HEIGHT);// Build and compile our shader programShader ourShader(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Shader\\vertexShader.txt, C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Shader\\fragmentShader.txt);// Set up vertex data (and buffer(s)) and attribute pointersGLfloat vertices[] {// Positions // Colors // Texture Coords0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // Top Right0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // Bottom Right-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // Bottom Left-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // Top Left };GLuint indices[] { // Note that we start from 0!0, 1, 3, // First Triangle1, 2, 3 // Second Triangle};GLuint VBO, VAO, EBO;glGenVertexArrays(1, VAO);glGenBuffers(1, VBO);glGenBuffers(1, EBO);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);// Position attributeglVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)0);glEnableVertexAttribArray(0);// Color attributeglVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));glEnableVertexAttribArray(1);// TexCoord attributeglVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (GLvoid*)(6 * sizeof(GLfloat)));glEnableVertexAttribArray(2);glBindVertexArray(0); // Unbind VAO// Load and create a texture GLuint texture1;GLuint texture2;// // Texture 1// glGenTextures(1, texture1);glBindTexture(GL_TEXTURE_2D, texture1); // All upcoming GL_TEXTURE_2D operations now have effect on our texture object// Set our texture parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // Set texture wrapping to GL_REPEATglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);// Set texture filteringglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);// Load, create texture and generate mipmapsint width, height;unsigned char* image SOIL_load_image(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Resource\\container.jpg, width, height, 0, SOIL_LOAD_RGB);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);glBindTexture(GL_TEXTURE_2D, 0); // Unbind texture when done, so we wont accidentily mess up our texture.// // Texture 2// glGenTextures(1, texture2);glBindTexture(GL_TEXTURE_2D, texture2);// Set our texture parametersglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_BORDER);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);float borderColor[] { 1.0f, 1.0f , 0.0f, 1.0f };glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, borderColor);// Set texture filteringglTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);// Load, create texture and generate mipmapsimage SOIL_load_image(C:\\Users\\32156\\source\\repos\\LearnOpenGL\\Resource\\awesomeface.png, width, height, 0, SOIL_LOAD_RGB);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);glGenerateMipmap(GL_TEXTURE_2D);SOIL_free_image_data(image);glBindTexture(GL_TEXTURE_2D, 0);// Game loopwhile (!glfwWindowShouldClose(window)){// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functionsglfwPollEvents();// Render// Clear the colorbufferglClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);// Activate shaderourShader.Use();glm::mat4 trans glm::mat4(1.0f);trans glm::rotate(trans, (GLfloat)glfwGetTime() * 2.0f, glm::vec3(0.0f, 0.0f, 1.0f));trans glm::translate(trans, glm::vec3(0.5f, -0.5f, 0.0f));// Bind Textures using texture unitsglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, texture1);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture1), 0);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, texture2);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture2), 1);GLuint transformLoc glGetUniformLocation(ourShader.Program, transform);glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));// 设置混合参数glUniform1f(glGetUniformLocation(ourShader.Program,mixValue),mixValue);// Draw containerglBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);glBindVertexArray(0);// Swap the screen buffersglfwSwapBuffers(window);}// Properly de-allocate all resources once theyve outlived their purposeglDeleteVertexArrays(1, VAO);glDeleteBuffers(1, VBO);glDeleteBuffers(1, EBO);// Terminate GLFW, clearing any resources allocated by GLFW.glfwTerminate();return 0;
}// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{if (key GLFW_KEY_ESCAPE action GLFW_PRESS)glfwSetWindowShouldClose(window, GL_TRUE);if (key GLFW_KEY_UP action GLFW_PRESS){mixValue 0.1f;if (mixValue 1.0f)mixValue 1.0f;}if (key GLFW_KEY_DOWN action GLFW_PRESS){mixValue - 0.1f;if (mixValue 0.0f)mixValue 0.0f;}
}练习二 尝试再次调用glDrawElements画出第二个箱子只使用变换将其摆放在不同的位置。让这个箱子被摆放在窗口的左上角并且会不断的缩放而不是旋转。sin函数在这里会很有用不过注意使用sin函数时应用负值会导致物体被翻转。 最终效果 其实还是很简单的直接上核心代码
while (!glfwWindowShouldClose(window)){// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functionsglfwPollEvents();// Render// Clear the colorbufferglClearColor(0.2f, 0.3f, 0.3f, 1.0f);glClear(GL_COLOR_BUFFER_BIT);// Activate shaderourShader.Use();// 计算右下角笑脸的变换矩阵glm::mat4 trans glm::mat4(1.0f);trans glm::translate(trans, glm::vec3(0.5f, -0.5f, 0.0f));trans glm::rotate(trans, (GLfloat)glfwGetTime() * 2.0f, glm::vec3(0.0f, 0.0f, 1.0f));GLuint transformLoc glGetUniformLocation(ourShader.Program, transform);glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));// Bind Textures using texture unitsglActiveTexture(GL_TEXTURE0);glBindTexture(GL_TEXTURE_2D, texture1);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture1), 0);glActiveTexture(GL_TEXTURE1);glBindTexture(GL_TEXTURE_2D, texture2);glUniform1i(glGetUniformLocation(ourShader.Program, ourTexture2), 1);// 设置混合参数glUniform1f(glGetUniformLocation(ourShader.Program,mixValue),mixValue);// Draw containerglBindVertexArray(VAO);glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);// 计算左上角笑脸的变换矩阵trans glm::mat4(1.0f);trans glm::translate(trans, glm::vec3(-0.5f, 0.5f, 0.0f));// 利用sin/20.5将时间 0到正无穷 转换为 0到1GLfloat scaleValue sin((GLfloat)glfwGetTime()) / 2 0.5;trans glm::scale(trans, glm::vec3(scaleValue,scaleValue,scaleValue));glUniformMatrix4fv(transformLoc, 1, GL_FALSE, glm::value_ptr(trans));glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);glBindVertexArray(0);// Swap the screen buffersglfwSwapBuffers(window);}
