第一篇文章(opengl es)

opengl es

顶点着色器 (vertex_shader.glsl)

#version 300 es

in vec4 a_position;
in vec3 a_normal;
in vec2 a_texCoord;

uniform mat4 u_mvpMatrix;
uniform mat4 u_modelMatrix;

out vec3 v_normal;
out vec2 v_texCoord;

void main() {
    gl_Position = u_mvpMatrix * a_position;
    v_normal = mat3(u_modelMatrix) * a_normal;
    v_texCoord = a_texCoord;
}

**

片段着色器 (fragment_shader.glsl)

#version 300 es

precision mediump float;

in vec3 v_normal;
in vec2 v_texCoord;

uniform sampler2D u_texture;

out vec4 fragColor;

void main() {
    fragColor = texture(u_texture, v_texCoord);
}

**

主程序 (main.cpp)

#include <GLES3/gl3.h>
#include <EGL/egl.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <iostream>
#include <vector>

// 顶点和纹理坐标
const std::vector<GLfloat> vertices = {
    // 前
    -1.0f, -1.0f,  1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
     1.0f, -1.0f,  1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f,
     1.0f,  1.0f,  1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f,
    -1.0f,  1.0f,  1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f,
    // 后
    -1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f,
     1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f,
     1.0f,  1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f,
    -1.0f,  1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f,
    // 左
    -1.0f, -1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
    -1.0f, -1.0f,  1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
    -1.0f,  1.0f,  1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
    -1.0f,  1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
    // 右
     1.0f, -1.0f,  1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
     1.0f, -1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f,
     1.0f,  1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
     1.0f,  1.0f,  1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f,
    // 上
    -1.0f,  1.0f,  1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
     1.0f,  1.0f,  1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,
     1.0f,  1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f,
    -1.0f,  1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f,
    // 下
    -1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f,
     1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f,
     1.0f, -1.0f,  1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f,
    -1.0f, -1.0f,  1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f
};

const std::vector<GLushort> indices = {
    0, 1, 2, 2, 3, 0, // 前
    4, 5, 6, 6, 7, 4, // 后
    8, 9, 10, 10, 11, 8, // 左
    12, 13, 14, 14, 15, 12, // 右
    16, 17, 18, 18, 19, 16, // 上
    20, 21, 22, 22, 23, 20 // 下
};

GLuint loadShader(GLenum type, const char *source) {
    GLuint shader = glCreateShader(type);
    glShaderSource(shader, 1, &source, nullptr);
    glCompileShader(shader);
    return shader;
}

GLuint createProgram(const char *vertexSource, const char *fragmentSource) {
    GLuint vertexShader = loadShader(GL_VERTEX_SHADER, vertexSource);
    GLuint fragmentShader = loadShader(GL_FRAGMENT_SHADER, fragmentSource);
    GLuint program = glCreateProgram();
    glAttachShader(program, vertexShader);
    glAttachShader(program, fragmentShader);
    glLinkProgram(program);
    return program;
}

int main(int argc, char **argv) {
    // 初始化EGL
    EGLDisplay display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
    eglInitialize(display, nullptr, nullptr);

    EGLint configAttribs[] = {
        EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
        EGL_BLUE_SIZE, 8,
        EGL_GREEN_SIZE, 8,
        EGL_RED_SIZE, 8,
        EGL_DEPTH_SIZE, 8,
        EGL_RENDERABLE_TYPE, EGL_OPENGL_ES3_BIT,
        EGL_NONE
    };

    EGLConfig config;
    EGLint numConfigs;
    eglChooseConfig(display, configAttribs, &config, 1, &numConfigs);

    EGLSurface surface = eglCreateWindowSurface(display, config, EGL_DEFAULT_DISPLAY, nullptr);

    EGLint contextAttribs[] = {EGL_CONTEXT_CLIENT_VERSION, 3, EGL_NONE};
    EGLContext context = eglCreateContext(display, config, EGL_NO_CONTEXT, contextAttribs);

    eglMakeCurrent(display, surface, surface, context);

    // 创建着色器程序
    const char *vertexShaderSource = R"(
        #version 300 es
        in vec4 a_position;
        in vec3 a_normal;
        in vec2 a_texCoord;
        uniform mat4 u_mvpMatrix;
        uniform mat4 u_modelMatrix;
        out vec3 v_normal;
        out vec2 v_texCoord;
        void main() {
            gl_Position = u_mvpMatrix * a_position;
            v_normal = mat3(u_modelMatrix) * a_normal;
            v_texCoord = a_texCoord;
        }
    )";

    const char *fragmentShaderSource = R"(
        #version 300 es
        precision mediump float;
        in vec3 v_normal;
        in vec2 v_texCoord;
        uniform sampler2D u_texture;
        out vec4 fragColor;
        void main() {
            fragColor = texture(u_texture, v_texCoord);
        }
    )";

    GLuint program = createProgram(vertexShaderSource, fragmentShaderSource);
    glUseProgram(program);

    // 获取uniform变量的位置
    GLint u_mvpMatrixLocation = glGetUniformLocation(program, "u_mvpMatrix");
    GLint u_modelMatrixLocation = glGetUniformLocation(program, "u_modelMatrix");

    // 创建VBO和VAO
    GLuint vbo, vao, ebo;
    glGenBuffers(1, &vbo);
    glGenBuffers(1, &ebo);
    glGenVertexArrays(1, &vao);

    glBindVertexArray(vao);
    glBindBuffer(GL_ARRAY_BUFFER, vbo);
    glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(GLfloat), vertices.data(), GL_STATIC_DRAW);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ebo);
    glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(GLushort), indices.data(), GL_STATIC_DRAW);

    // 设置顶点属性指针
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)0);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(3 * sizeof(GLfloat)));
    glEnableVertexAttribArray(1);
    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 8 * sizeof(GLfloat), (void*)(6 * sizeof(GLfloat)));
    glEnableVertexAttribArray(2);

    // 加载纹理
    GLuint texture;
    glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 1, 1, 0, GL_RGB, GL_UNSIGNED_BYTE, nullptr);

    // 设置视图和投影矩阵
    glm::mat4 viewMatrix = glm::lookAt(glm::vec3(0.0f, 0.0f, 5.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
    glm::mat4 projectionMatrix = glm::perspective(glm::radians(45.0f), 800.0f / 600.0f, 0.1f, 100.0f);

    // 主循环
    float rotationAngle = 0.0f;
    float scaleFactor = 1.0f;

    while (true) {
        // 处理输入
        // 例如：rotationAngle += 1.0f; scaleFactor += 0.01f;

        // 设置模型矩阵
        glm::mat4 modelMatrix = glm::mat4(1.0f);
        modelMatrix = glm::scale(modelMatrix, glm::vec3(scaleFactor, scaleFactor, scaleFactor));
        modelMatrix = glm::rotate(modelMatrix, glm::radians(rotationAngle), glm::vec3(0.0f, 1.0f, 0.0f));

        glm::mat4 mvpMatrix = projectionMatrix * viewMatrix * modelMatrix;

        // 上传矩阵到着色器
        glUniformMatrix4fv(u_mvpMatrixLocation, 1, GL_FALSE, glm::value_ptr(mvpMatrix));
        glUniformMatrix4fv(u_modelMatrixLocation, 1, GL_FALSE, glm::value_ptr(modelMatrix));

        // 清除颜色和深度缓冲区
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        // 绘制正方体
        glDrawElements(GL_TRIANGLES, indices.size(), GL_UNSIGNED_SHORT, 0);

        // 交换缓冲区
        eglSwapBuffers(display, surface);
    }

    // 清理
    glDeleteProgram(program);
    glDeleteBuffers(1, &vbo);
    glDeleteBuffers(1, &ebo);
    glDeleteVertexArrays(1, &vao);
    glDeleteTextures(1, &texture);

    eglDestroyContext(display, context);
    eglDestroySurface(display, surface);
    eglTerminate(display);

    return 0;
}

**

说明

1. 顶点着色器和片段着色器分别定义了顶点和片段的处理逻辑。
2. 主程序中包含了EGL初始化、着色器程序创建、顶点数据绑定、矩阵设置、绘制循环等步骤。
3. 在主循环中，你可以通过修改rotationAngle和scaleFactor来控制正方体的旋转和缩放。