OpenGL ES 3.0 Hello_Triangle

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OpenGL ES 3.0学习汇总

• OpenGL ES 3.0 学习记录汇总

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Hello_Triangle

官方源代码原始链接

#include "esUtil.h"
typedef struct {
    GLuint programObject;
}TestUserData;

int TestloadShader(GLenum type, const char *shaderSrc) {
    GLuint shader;
    GLuint complied;
    //创建着色器对象
    shader = glCreateShader(type);
    if (shader == 0) {
        return 0;
    }
    //加载着色器源程序
    glShaderSource(shader, 1, &shaderSrc, NULL);
    //编译着色器源程序
    glCompileShader(shader);

    //检查编译的状态
    glGetShaderiv(shader, GL_COMPILE_STATUS, &complied);

    if (!complied) {
        GLint infoLen = 0;

        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);

        if (infoLen > 1) {
            char *infoLog = malloc(sizeof(char) * infoLen);

            glGetShaderInfoLog(shader, infoLen, NULL, &infoLog);
            esLogMessage("Error compiling shader:\n%s\n", infoLog);

            free(infoLog);
        }
        glDeleteShader(shader);
        return 0;
    }
    return shader;
}

int TestInit(ESContext *esContext) {
    TestUserData *userData = esContext->userData;
    char vShaderStr[] = "#version 300 es \n"
        "layout (location = 0) in vec4 vPosition; \n"
        "void main() { \n"
        "glPosition = vPosition; \n"
        "}";
    char fShaderStr[] = "#version 300 es \n"
        "precision mediump float; \n"
        "out vec4 fragColor; \n"
        "void main() { \n"
        "fragColor = vec4(1.0, 0.0, 0.0, 1.0)"
        "} ";
    GLuint vertexShader;
    GLuint fragmentShader;
    GLuint programObject;
    GLuint linked;

    //加载 顶点 和 片段  着色器
    vertexShader = TestloadShader(GL_VERTEX_SHADER, vShaderStr);
    fragmentShader = TestloadShader(GL_FRAGMENT_SHADER, fShaderStr);

    //创建程序
    programObject = glCreateProgram();

    if (programObject == 0) {
        return 0;
    }


    glAttachShader(programObject, vertexShader);
    glAttachShader(programObject, fragmentShader);

    //链接程序
    glLinkProgram(programObject);
    
    //检查程序链接状态
    glGetProgramiv(programObject, GL_LINK_STATUS, &linked);

    if (!linked) {
        GLint infoLen = 0;

        glGetProgramiv(programObject, GL_INFO_LOG_LENGTH, &infoLen);

        if (infoLen > 1) {
            char *infoLog = malloc(sizeof(char) * infoLen);

            glGetProgramInfoLog(programObject, infoLen, NULL, infoLog);
            esLogMessage("Eroor linking program:\n%s\n", infoLog);

            free(infoLog);
        }
        glDeleteProgram(programObject);
        return FALSE;
    }

    userData->programObject = programObject;

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    return TRUE;
}

void TestDraw(ESContext *esContext) {
    TestUserData *userData = esContext->userData;
    GLfloat vVertices[] = {
        0.0f, 0.5f, 0.0f,
        -0.5f, -0.5f, 0.0f,
        0.5f, 0.5f, 0.0f
    };

    //设置一个窗口
    glViewport(0, 0, esContext->width, esContext->height);

    //清空颜色缓冲区
    glClear(GL_COLOR_BUFFER_BIT);

    //设置为活动程序
    glUseProgram(userData->programObject);

    //加载顶点坐标数据
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, vVertices);
    glEnableVertexAttribArray(0);

    glDrawArrays(GL_TRIANGLES, 0, 3);

}

void TestShutdown(ESContext *esContext) {
    TestUserData *userData = esContext->userData;
    glDeleteProgram(userData->programObject);
}

int TestesMain(ESContext *esContext) {
    esContext->userData = malloc(sizeof(TestUserData));

    esCreateWindow(esContext, "Hello Triangel", 800, 800, ES_WINDOW_RGB);

    if (!TestInit(esContext)) {
        return GL_FALSE;
    }

    esRegisterShutdownFunc(esContext, TestShutdown);
    esRegisterDrawFunc(esContext, TestDraw);

    return GL_TRUE;
}