在开发板上，使用OpenGL相关API绘制基本图形流程

如果使用OpenGL API直接绘制基本图形，需要依赖OpenHarmony的接口层的相关API，如何方便使用，主要参考Gitee项目（https://gitee.com/honglianglin/glmark2_2）。

hdc_std shell mount -o remount,rw /
hdc_std file send libnative_window_wrapper.z.so /system/lib

#ifndef NATIVE_WINDOW_WRAPPER
#define NATIVE_WINDOW_WRAPPER
#include <cstdint>
extern "C" {
    typedef struct {
        void* (*CreateWindowWrapper)();
        bool (*CreateWindow)(void* wrapper, uint32_t w, uint32_t h);
        void* (*GetNativeWindow)(void* wrapper);
        void (*SetVisibility)(void* wrapper, bool visible);
        void (*DestroyWindowWrapper)(void* wrapper);
    } WrapperFunc;
    bool GetWrapperFunc(WrapperFunc* funcs);    
}
#endif // NATIVE_WINDOW_WRAPPER

├── include
│   └── native_window_wrapper.h
├── main.cpp
├── Makefile
└── src
├── canvas-generic.cpp
├── canvas-generic.h
├── canvas.h
├── glad
├── gl-headers.cpp
├── gl-headers.h
├── gl-state-egl.cpp
├── gl-state-egl.h
├── gl-state.h
├── gl-visual-config.cpp
├── gl-visual-config.h
├── include
├── libmatrix
├── native-state.h
├── native-state-ohos.cpp
├── native-state-ohos.h
├── ohos_wrapper_linker.cpp
├── ohos_wrapper_linker.h
├── options.cpp
├── options.h
├── shared-library.cpp
└── shared-library.h

OHOS_ROOT = /home/algoideas/openharmony/master
CC = $(OHOS_ROOT)/prebuilts/clang/ohos/linux-x86_64/llvm/bin/clang --sysroot=$(OHOS_ROOT)/out/a311d/obj/third_party/musl
CXX = $(OHOS_ROOT)/prebuilts/clang/ohos/linux-x86_64/llvm/bin/clang++ --sysroot=$(OHOS_ROOT)/out/a311d/obj/third_party/musl
AR = $(OHOS_ROOT)/prebuilts/clang/ohos/linux-x86_64/llvm/bin/llvm-ar
LD = $(OHOS_ROOT)/prebuilts/clang/ohos/linux-x86_64/llvm/bin/llvm-link
ARFLAG = -rcs
TARGET = native_main
PROJECT_PATH = $(shell pwd)

CFLAGS := -march=armv7-a \
    -mfloat-abi=softfp \
    -mtune=generic-armv7-a \
    -mfpu=neon \
    -mthumb \
    --target=arm-linux-ohosmusl \
    --sysroot=$(OHOS_ROOT)/out/rk3568/obj/third_party/musl
# Warning
CFLAGS += -Wno-c++11-narrowing
# Lib
CLIBS = -lm -ldl -lrt
CLIBS += -L$(OHOS_ROOT)/device/soc/rockchip/hardware/gpu/lib -lmali-bifrost-g52-g2p0-ohos
CLIBS += -L$(OHOS_ROOT)/out/rk3568/packages/phone/system/lib -lhilog -lsurface.z -lutils.z
CFLAGS += -DOHOS_USE_DRM -DOHOS_USE_GLESv2 -DOHOS_USE_EGL
INCLUDE_DIRS += \
    -I$(OHOS_ROOT)/third_party/EGL/api \
    -I$(OHOS_ROOT)/third_party/openGLES/api \
    -I$(OHOS_ROOT)/utils/native/base/include \
    -I$(OHOS_ROOT)/drivers/peripheral/base \
    -I$(OHOS_ROOT)/foundation/graphic/standard/interfaces/innerkits/common \
    -I$(OHOS_ROOT)/foundation/graphic/standard/interfaces/innerkits/surface \
    -I$(OHOS_ROOT)/foundation/graphic/standard/utils/buffer_handle/export \
    -I$(OHOS_ROOT)/foundation/communication/ipc/interfaces/innerkits/ipc_core/include \
    -I$(OHOS_ROOT)/foundation/aafwk/standard/frameworks/kits/ability/ability_runtime/include \
    -I$(OHOS_ROOT)/foundation/aafwk/standard/interfaces/innerkits/ability_manager/include  \
    -I$(OHOS_ROOT)/foundation/aafwk/standard/interfaces/innerkits/app_manager/include/appmgr  \
    -I$(OHOS_ROOT)/third_party/jsoncpp/include  \
    -I$(OHOS_ROOT)/third_party/json/include  \
    -I$(OHOS_ROOT)/foundation/windowmanager/interfaces/innerkits/wm \
    -I$(OHOS_ROOT)/foundation/graphic/standard/frameworks/surface \
    -I$(OHOS_ROOT)/foundation/graphic/standard/rosen/modules/render_service_base/include \
    -I$(OHOS_ROOT)/foundation/graphic/standard/rosen/modules/render_service_client/core \
    -I$(OHOS_ROOT)/foundation/graphic/standard/rosen/modules/render_service_client \
    -I$(OHOS_ROOT)/third_party/flutter/skia \
    -I$(OHOS_ROOT)/third_party/flutter/skia/include/core \
    -I$(OHOS_ROOT) \
    -I$(OHOS_ROOT)/third_party/skia
INCLUDE_DIRS += -I$(PROJECT_PATH)/include \
    -I$(PROJECT_PATH)/src/glad/include \
    -I$(PROJECT_PATH)/src/libmatrix \
    -I$(PROJECT_PATH)/src 
export CC CXX CFLAGS AR LD ARFLAG MODULE_SELECT
CPP_SOURCES = $(wildcard ./src/*.cpp)
CPP_OBJECTS = $(patsubst %.cpp,%.o,$(CPP_SOURCES))

#include "gl-headers.h"
#include "options.h"
#include "log.h"
#include "util.h"
#include "canvas-generic.h"
#include "native-state-ohos.h"
#include "gl-state-egl.h"
using std::vector;
using std::string;
int main(int argc, char *argv[])
{
    if (!Options::parse_args(argc, argv))
        return 1;
    /* Initialize Log class */
    Log::init(Util::appname_from_path(argv[0]), Options::show_debug);
    if (Options::show_help) {
        Options::print_help();
        return 0;
    }
    /* Force 320x240 output for validation */
    if (Options::validate &&
        Options::size != std::pair<int,int>(320, 240))
    {
        Log::info("Ignoring custom size %dx%d for validation. Using 800x600.\n",
                  Options::size.first, Options::size.second);
        Options::size = std::pair<int,int>(320, 240);
    }
    // Create the canvas
    NativeStateOhos native_state;
    GLStateEGL gl_state;
    CanvasGeneric canvas(native_state, gl_state, Options::size.first, Options::size.second);
    canvas.offscreen(Options::offscreen);
    canvas.visual_config(Options::visual_config);
    if (!canvas.init()) {
        Log::error("%s: Could not initialize canvas\n", __FUNCTION__);
        return 1;
    }
    Log::info("=======================================================\n");
    canvas.print_info();
    Log::info("=======================================================\n");
    canvas.visible(true);
     /**
      ** 数据处理: 生成和绑定VBO, 设置属性指针
      **/
    // 三角形的顶点数据, 规范化(x,y,z)都要映射到[-1,1]之间
    const float triangle[] = {
        // 位置
        -0.5f, -0.5f, 0.0f,  // 左下
         0.5f, -0.5f, 0.0f,  // 右下
         0.0f,  0.5f, 0.0f   // 正上
    };
    // 生成并绑定立方体的VBO
    GLuint vertex_buffer_object; // VBO
    glGenBuffers(1, &vertex_buffer_object);
    glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer_object);
    // 将顶点数据绑定到当前默认的缓冲中, 好处是不用将顶点数据一个一个地发送到显卡上, 可以借助VBO一次性发送所有顶点数据
    // GL_STATIC_DRAW表示顶点数据不会被改变
    glBufferData(GL_ARRAY_BUFFER, sizeof(triangle), triangle, GL_STATIC_DRAW);
    // 设置顶点属性指针
    // 第一个参数0: 顶点着色器的位置值
    // 第二个参数3: 位置属性是一个三分量的向量
    // 第三个参数: 顶点的类型
    // 第四个参数: 是否希望数据标准化,映射到[0,1]
    // 第五个参数: 步长,表示连续顶点属性之间的间隔,下一组的数据再3个float之后
    // 第六个参数: 数据的偏移量, 位置属性在开头, 因此为0, 还需要强制类型转换
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *)0);
    glEnableVertexAttribArray(0); // 开启0通道
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    /**
     ** 着色器: 顶点和片段着色器
     **/
    /* 着色器源码 -> 生成并编译着色器 -> 链接着色器到着色器程序 -> 删除着色器 */
    const char *vertex_shader_source =
            "attribute vec4 a_Position;\n" // 位置变量属性设置为0
            "void main()\n"
            "{\n"
            "    gl_Position = a_Position;\n"
            "}\n\0";

    /* 设置片元像素的颜色为红色, vec4(r,g,b,a) */
    const char *fragment_shader_source =
            "void main()\n"
            "{\n"
            "    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n"
            "}\n\0";
    /**
     ** 生成并编译着色器 
     **/
    /* 顶点着色器 */
    int vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    glShaderSource(vertex_shader, 1, &vertex_shader_source, NULL);
    glCompileShader(vertex_shader);
    int success;
    char info_log[512];
    /* 检查着色器是否成功编译, 如果编译失败, 打印错误信息 */
    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &success);
    if(!success){
        glGetShaderInfoLog(vertex_shader, 512, NULL, info_log);
        Log::error("SHADER::VERTEX::COMPILATION_FAIILED %s\n", info_log);
    }
    /* 片元着色器 */
    int fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
    glShaderSource(fragment_shader, 1, &fragment_shader_source, NULL);
    glCompileShader(fragment_shader);

    /* 检查着色器是否成功编译, 如果编译失败, 打印错误信息 */
    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &success);
    if(!success){
        glGetShaderInfoLog(fragment_shader, 512, NULL, info_log);
        Log::error("glGetShaderiv fragment_shader fail %s\n", info_log);
    }
    /* 链接顶点和片段着色器至一个着色器程序 */
    int shader_program = glCreateProgram();
    glAttachShader(shader_program, vertex_shader);
    glAttachShader(shader_program, fragment_shader);
    glLinkProgram(shader_program);
    /* 检查着色器是否成功链接, 如果链接失败, 打印错误信息 */
    glGetProgramiv(shader_program, GL_LINK_STATUS, &success);
    if(!success){
        glGetProgramInfoLog(shader_program, 512, NULL, info_log);
        Log::error("glGetShaderiv shader_program fail %s\n", info_log);
    }
    /* 删除顶点和片段着色器 */
    glDeleteShader(vertex_shader);
    glDeleteShader(fragment_shader);
    /**
     ** 渲染
     **/
    /* 清空颜色缓冲 */
    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);   // 用黑色背景色来清空
    glClear(GL_COLOR_BUFFER_BIT);
    /* 使用着色器程序 */
    glUseProgram(shader_program);
    /* 绘制三角形 */
    glDrawArrays(GL_TRIANGLES, 0, 3); // 绘制三角形, 绘制三角形, 顶点起始索引值, 绘制数量
    /* 更新交换缓冲 */
    canvas.update();
    glDeleteBuffers(1, &vertex_buffer_object);
    getchar();
    return 0;
}