接着之前的OpenGL_Learn05（纹理）-CSDN博客
1. 修改片段着色器
修改片段着色器，仅让笑脸图案朝另一个方向看
========>>>>>
纹理坐标的Y轴没有进行改变，需要改变的是X轴的纹理坐标
片段代码改写如下
#version 330 core
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
//texture sampler
uniform sampler2D textureone;
uniform sampler2D texturetwo;
void main()
{
FragColor = mix(texture(textureone,TexCoord),texture(texturetwo,vec2(1.0-TexCoord.x,TexCoord.y)),0.5);
}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。
原纹理坐标 ：
//4. 设置顶点数据
float vertices[] = {
// positions // colors // texture 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
};
改成如下：
//4. 设置顶点数据
float vertices[] = {
// positions // colors // texture 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
};
3. 纹理过滤
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。
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "stb_image.h"
#include <cmath>
#include "shader.h"
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() {
//1.初始化配置
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, GLFW_TRUE);
#endif // __APPLE__
//2.gltf 窗口创建
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LeranOpenGL", NULL, NULL);
if (window == NULL) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//3. 加载所有GL函数指针
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
Shader ourShader("./texture.vs", "./texture.fs");
//4. 设置顶点数据
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
};
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);//元素缓冲对象：Element Buffer Object，EBO
glBindVertexArray(VAO);
//复制顶点数组到缓冲区中供opengl使用
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);
//设置顶点属性指针
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
//设置颜色属性指针
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
//设置纹理属性指针
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
//加载和创建纹理
unsigned int textureone,texturetwo;
glGenTextures(1, &textureone);
glBindTexture(GL_TEXTURE_2D, textureone);
//设置纹理环绕参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
//设置纹理过滤参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
//加载图像和生成mipmaps
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(true);
std::string filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\container.jpg)";
unsigned char* data = stbi_load(filePath.c_str(), &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);
glGenTextures(1, &texturetwo);
glBindTexture(GL_TEXTURE_2D, texturetwo);
//设置纹理环绕参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//设置纹理过滤参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
//加载图像和生成mipmaps
filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\awesomeface.png)";
unsigned char* data2 = stbi_load(filePath.c_str(), &width, &height, &nrChannels, 0);
if (data2) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data2);
glGenerateMipmap(GL_TEXTURE_2D);
}
else {
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data2);
ourShader.use();
glUniform1i(glGetUniformLocation(ourShader.ID, "textureone"), 0);//二选一
ourShader.setInt("texturetwo", 1);//二选一
//5. 循环渲染
while (!glfwWindowShouldClose(window)) {
processInput(window);
// render
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
//绑定纹理
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textureone);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texturetwo);
ourShader.use();
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,0);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
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);
}
4. 动态调节纹理可见度
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。
texture.fs
#version 330 core
out vec4 FragColor;
in vec3 ourColor;
in vec2 TexCoord;
uniform float mixValue;
//texture sampler
uniform sampler2D textureone;
uniform sampler2D texturetwo;
void main()
{
FragColor = mix(texture(textureone,TexCoord),texture(texturetwo,vec2(1.0-TexCoord.x,TexCoord.y)),mixValue);
}main.cpp
#include <glad/glad.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include "stb_image.h"
#include <cmath>
#include "shader.h"
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;
float mixValue = 0.2f;
int main() {
//1.初始化配置
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, GLFW_TRUE);
#endif // __APPLE__
//2.gltf 窗口创建
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "LeranOpenGL", NULL, NULL);
if (window == NULL) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
//3. 加载所有GL函数指针
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
std::cout << "Failed to initialize GLAD" << std::endl;
return -1;
}
Shader ourShader("./texture.vs", "./texture.fs");
//4. 设置顶点数据
float vertices[] = {
// positions // colors // texture 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);//元素缓冲对象：Element Buffer Object，EBO
glBindVertexArray(VAO);
//复制顶点数组到缓冲区中供opengl使用
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);
//设置顶点属性指针
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
//设置颜色属性指针
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
//设置纹理属性指针
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(float), (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
//加载和创建纹理
unsigned int textureone,texturetwo;
glGenTextures(1, &textureone);
glBindTexture(GL_TEXTURE_2D, textureone);
//设置纹理环绕参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//设置纹理过滤参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//加载图像和生成mipmaps
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(true);
std::string filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\container.jpg)";
unsigned char* data = stbi_load(filePath.c_str(), &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);
glGenTextures(1, &texturetwo);
glBindTexture(GL_TEXTURE_2D, texturetwo);
//设置纹理环绕参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//设置纹理过滤参数
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
//加载图像和生成mipmaps
filePath = R"(D:\CPlusProject\LearnOpenGL\DataSet\awesomeface.png)";
unsigned char* data2 = stbi_load(filePath.c_str(), &width, &height, &nrChannels, 0);
if (data2) {
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data2);
glGenerateMipmap(GL_TEXTURE_2D);
}
else {
std::cout << "Failed to load texture" << std::endl;
}
stbi_image_free(data2);
ourShader.use();
glUniform1i(glGetUniformLocation(ourShader.ID, "textureone"), 0);//二选一
ourShader.setInt("texturetwo", 1);//二选一
//5. 循环渲染
while (!glfwWindowShouldClose(window)) {
processInput(window);
// render
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
//绑定纹理
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, textureone);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, texturetwo);
ourShader.setFloat("mixValue", mixValue);
ourShader.use();
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,0);
glfwSwapBuffers(window);
glfwPollEvents();
}
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
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);
if (glfwGetKey(window, GLFW_KEY_UP) == GLFW_PRESS) {
std::cout << "up" << std::endl;
mixValue += 0.001f;
if (mixValue >= 1.0f) {
mixValue = 1.0f;
}
}
if (glfwGetKey(window, GLFW_KEY_DOWN) == GLFW_PRESS)
{
std::cout << "down" << std::endl;
mixValue -= 0.001f; // change this value accordingly (might be too slow or too fast based on system hardware)
if (mixValue <= 0.0f)
mixValue = 0.0f;
}
std::cout << "mixValue:" << mixValue <<std::endl;
}
// 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);
} 
纹理 - LearnOpenGL CN (learnopengl-cn.github.io)
