OpenGL-04-02练习题
02 04 OpenGL 练习题
2023-09-11 14:22:30 时间
OpenGL-04-02练习题
一、修改片段着色器，仅让笑脸图案朝另一个方向看
#version 330 core
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
// texture sampler
uniform sampler2D texture1;
uniform sampler2D texture2;
void main()
{
FragColor = mix(texture(texture1, TexCoord), texture(texture2, vec2(-TexCoord.x,TexCoord.y)), 0.2);
}
二、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。
这里要测试不同的环绕方式
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <myShader.h>
#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
int main()
{
#pragma region glfw
// glfw: initialize and configure
// ------------------------------
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
// glfw window creation
// --------------------
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
// glad: load all OpenGL function pointers
// ---------------------------------------
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
#pragma endregion
// build and compile our shader zprogram
// ------------------------------------
Shader ourShader("path/to/shaders/shader.vs", "path/to/shaders/shader.fs");
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
// positions // colors // texture1 coords
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 2.0f, 2.0f, // top right
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 2.0f, 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, 2.0f // top left
};
unsigned int indices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
unsigned int 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 attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// texture1 coord attribute
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
// load and create a texture1
// -------------------------
//创建纹理ID
unsigned int texture1;
//生成纹理对象，并存储在texture中
glGenTextures(1, &texture1);
//绑定当前的纹理
glBindTexture(GL_TEXTURE_2D,texture1); // all upcoming GL_TEXTURE_2D operations now have effect on this texture1 object
// 为当前绑定的纹理对象设置环绕、过滤方式
// set the texture1 wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // set texture1 wrapping to GL_REPEAT (default wrapping method)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
// 为当前绑定的纹理对象设置环绕、过滤方式
// set texture1 filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// load image, create texture1 and generate mipmaps
int width, height, nrChannels;
// The FileSystem::getPath(...) is part of the GitHub repository so we can find files on any IDE/platform; replace it with your own image path.
unsigned char *data = stbi_load("Texture/container.jpeg", &width, &height, &nrChannels, 0);
if (data)
{
//生成纹理
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
//这会为当前绑定的纹理自动生成所有需要的多级渐远纹理。
// glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture1" << std::endl;
}
//释放图像内存
stbi_image_free(data);
stbi_set_flip_vertically_on_load(true);
// load and create a texture1
// -------------------------
//创建纹理ID
unsigned int texture2;
//生成纹理对象，并存储在texture中
glGenTextures(1, &texture2);
//绑定当前的纹理
glBindTexture(GL_TEXTURE_2D,texture2); // all upcoming GL_TEXTURE_2D operations now have effect on this texture1 object
// 为当前绑定的纹理对象设置环绕、过滤方式
// set the texture1 wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); // set texture1 wrapping to GL_REPEAT (default wrapping method)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
// 为当前绑定的纹理对象设置环绕、过滤方式
// set texture1 filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// load image, create texture1 and generate mipmaps
// The FileSystem::getPath(...) is part of the GitHub repository so we can find files on any IDE/platform; replace it with your own image path.
data = stbi_load("Texture/awesomeface.png", &width, &height, &nrChannels, 0);
if (data)
{
//生成纹理.注意awesomeface.png有透明度和alpha通道，所以一定要告诉OpenGL的数据类型是GL_RGBA
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
//这会为当前绑定的纹理自动生成所有需要的多级渐远纹理。
// glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture1" << std::endl;
}
//释放图像内存
stbi_image_free(data);
// tell opengl for each sampler to which texture1 unit it belongs to (only has to be done once)
// -------------------------------------------------------------------------------------------
ourShader.use(); // don't forget to activate/use the shader before setting uniforms!
// either set it manually like so:
ourShader.setInt("texture1",0);
// or set it via the texture1 class
ourShader.setInt("texture2", 1);
// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
// input
// -----
processInput(window);
// render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
stbi_set_flip_vertically_on_load(true);
// bind Texture
// bind textures on corresponding texture1 units
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,texture1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D,texture2);
// render container
ourShader.use();
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
// optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
// glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return 0;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
// make sure the viewport matches the new window dimensions; note that width and
// height will be significantly larger than specified on retina displays.
glViewport(0, 0, width, height);
}
三、尝试在矩形上只显示纹理图像的中间一部分，修改纹理坐标，达到能看见单个的像素的效果。尝试使用GL_NEAREST的纹理过滤方式让像素显示得更清晰
实际上，纹理坐标类似于视口坐标系，左下角为(0,0)右上角为(1,1)代表本身，如果小于1就会放大图片，只显示坐标表示的部分范围，如果大于1，就会根据图像环绕方式去补充画面：重复出现，镜像重复，拉伸边缘，背景色填充多余区域
更改纹理坐标，缩小范围，然后把过滤方式改为邻近过滤，就能看见像素
float vertices[] = {
// positions // colors // texture coords (note that we changed them to 'zoom in' on our texture image)
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 0.55f, 0.55f, // top right
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 0.55f, 0.45f, // bottom right
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.45f, 0.45f, // bottom left
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.45f, 0.55f // top left
};
四、使用一个uniform变量作为mix函数的第三个参数来改变两个纹理可见度，使用上和下键来改变箱子或笑脸的可见度
比较简单，判断输入键盘，更改值即可
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <myShader.h>
#define STB_IMAGE_IMPLEMENTATION
#include <stb_image.h>
#include <iostream>
void framebuffer_size_callback(GLFWwindow* window, int width, int height);
void processInput(GLFWwindow *window);
float virtualInput(GLFWwindow *window,float value);
// settings
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
int main()
{
#pragma region glfw
// glfw: initialize and configure
// ------------------------------
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
#ifdef __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
#endif
// glfw window creation
// --------------------
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LearnOpenGL", NULL, NULL);
if (window == NULL)
{
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
// glad: load all OpenGL function pointers
// ---------------------------------------
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
{
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
#pragma endregion
// build and compile our shader zprogram
// ------------------------------------
Shader ourShader("path/to/shaders/shader.vs", "path/to/shaders/shader.fs");
// set up vertex data (and buffer(s)) and configure vertex attributes
// ------------------------------------------------------------------
float vertices[] = {
// positions // colors // texture1 coords
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right
0.5f, -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
};
unsigned int indices[] = {
0, 1, 3, // first triangle
1, 2, 3 // second triangle
};
unsigned int 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 attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// texture1 coord attribute
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
// load and create a texture1
// -------------------------
//创建纹理ID
unsigned int texture1;
//生成纹理对象，并存储在texture中
glGenTextures(1, &texture1);
//绑定当前的纹理
glBindTexture(GL_TEXTURE_2D,texture1); // all upcoming GL_TEXTURE_2D operations now have effect on this texture1 object
// 为当前绑定的纹理对象设置环绕、过滤方式
// set the texture1 wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); // set texture1 wrapping to GL_REPEAT (default wrapping method)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
// 为当前绑定的纹理对象设置环绕、过滤方式
// set texture1 filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// load image, create texture1 and generate mipmaps
int width, height, nrChannels;
// The FileSystem::getPath(...) is part of the GitHub repository so we can find files on any IDE/platform; replace it with your own image path.
unsigned char *data = stbi_load("Texture/container.jpeg", &width, &height, &nrChannels, 0);
if (data)
{
//生成纹理
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
//这会为当前绑定的纹理自动生成所有需要的多级渐远纹理。
// glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture1" << std::endl;
}
//释放图像内存
stbi_image_free(data);
stbi_set_flip_vertically_on_load(true);
// load and create a texture1
// -------------------------
//创建纹理ID
unsigned int texture2;
//生成纹理对象，并存储在texture中
glGenTextures(1, &texture2);
//绑定当前的纹理
glBindTexture(GL_TEXTURE_2D,texture2); // all upcoming GL_TEXTURE_2D operations now have effect on this texture1 object
// 为当前绑定的纹理对象设置环绕、过滤方式
// set the texture1 wrapping parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT); // set texture1 wrapping to GL_REPEAT (default wrapping method)
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT);
// 为当前绑定的纹理对象设置环绕、过滤方式
// set texture1 filtering parameters
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// load image, create texture1 and generate mipmaps
// The FileSystem::getPath(...) is part of the GitHub repository so we can find files on any IDE/platform; replace it with your own image path.
data = stbi_load("Texture/awesomeface.png", &width, &height, &nrChannels, 0);
if (data)
{
//生成纹理.注意awesomeface.png有透明度和alpha通道，所以一定要告诉OpenGL的数据类型是GL_RGBA
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
//这会为当前绑定的纹理自动生成所有需要的多级渐远纹理。
// glGenerateMipmap(GL_TEXTURE_2D);
}
else
{
std::cout << "Failed to load texture1" << std::endl;
}
//释放图像内存
stbi_image_free(data);
// tell opengl for each sampler to which texture1 unit it belongs to (only has to be done once)
// -------------------------------------------------------------------------------------------
ourShader.use(); // don't forget to activate/use the shader before setting uniforms!
// either set it manually like so:
ourShader.setInt("texture1",0);
// or set it via the texture1 class
ourShader.setInt("texture2", 1);
ourShader.setFloat("mixScale",1);
float scale=1.0f;
// render loop
// -----------
while (!glfwWindowShouldClose(window))
{
// input
// -----
processInput(window);
// render
// ------
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
stbi_set_flip_vertically_on_load(true);
// bind Texture
// bind textures on corresponding texture1 units
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,texture1);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D,texture2);
// render container
ourShader.use();
scale=virtualInput(window,scale);
ourShader.setFloat("mixScale",scale);
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT,0);
// glfw: swap buffers and poll IO events (keys pressed/released, mouse moved etc.)
// -------------------------------------------------------------------------------
glfwSwapBuffers(window);
glfwPollEvents();
}
// optional: de-allocate all resources once they've outlived their purpose:
// ------------------------------------------------------------------------
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
// glfw: terminate, clearing all previously allocated GLFW resources.
// ------------------------------------------------------------------
glfwTerminate();
return 0;
}
float virtualInput(GLFWwindow *window,float value){
if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS){
value=value+0.1f;
if(value>1) value=1;
}else if(glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS){
value=value-0.1f;
if(value<0) value=0;
}
return value;
}
// process all input: query GLFW whether relevant keys are pressed/released this frame and react accordingly
// ---------------------------------------------------------------------------------------------------------
void processInput(GLFWwindow *window)
{
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
// glfw: whenever the window size changed (by OS or user resize) this callback function executes
// ---------------------------------------------------------------------------------------------
void framebuffer_size_callback(GLFWwindow* window, int width, int height)
{
// make sure the viewport matches the new window dimensions; note that width and
// height will be significantly larger than specified on retina displays.
glViewport(0, 0, width, height);
}
相关文章
- 02-个人博客笔记-登录注册接口的实现
- Yii 框架学习--02 进阶
- Kubernetes 笔记 02 demo 初体验
- 02_操作系统（科普章节）
- 【每日英语】2021-02-27
- 02进度控件-07多态进度条-progressthree
- Paper：《Explainable Artificial Intelligence (XAI): Concepts&可解释的人工智能：负责任人工智能的概念、分类法、机遇和挑战》翻译与解读02
- 《30天自制操作系统》笔记(02)——导入C语言
- HLS开发学习-02-HLS工作机制
- 风格迁移1-02：Liquid Warping GAN(Impersonator)-源码模型测试-报错解决
- Docker学习笔记02：Docker与虚拟化
- 02-线性结构4 Pop Sequence