OpenGL ES 绘制三角形，操作键盘移动位置
PS：想快速看到效果的小伙伴，可以在引入依赖后，先跳到完整代码部分
第一步：依赖引入
<properties><lwjgl.version>3.2.3</lwjgl.version><joml.version>1.9.25</joml.version><steamworks4j.version>1.8.0</steamworks4j.version><steamworks4j-server.version>1.8.0</steamworks4j-server.version></properties><profiles><profile><id>lwjgl-natives-macos-amd64</id><activation><os><family>mac</family><arch>amd64</arch></os></activation><properties><lwjgl.natives>natives-macos</lwjgl.natives></properties><dependencies><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-vulkan</artifactId><classifier>natives-macos</classifier></dependency></dependencies></profile><profile><id>lwjgl-natives-windows-amd64</id><activation><os><family>windows</family><arch>amd64</arch></os></activation><properties><lwjgl.natives>natives-windows</lwjgl.natives></properties></profile><profile><id>lwjgl-natives-windows-x86</id><activation><os><family>windows</family><arch>x86</arch></os></activation><properties><lwjgl.natives>natives-windows-x86</lwjgl.natives></properties></profile></profiles><dependencyManagement><dependencies><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-bom</artifactId><version>${lwjgl.version}</version><scope>import</scope><type>pom</type></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-assimp</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-bgfx</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-cuda</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-egl</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-glfw</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-jawt</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-jemalloc</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-libdivide</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-llvm</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-lmdb</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-lz4</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-meow</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-nanovg</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-nfd</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-nuklear</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-odbc</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-openal</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opencl</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opengl</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opengles</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-openvr</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opus</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-ovr</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-par</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-remotery</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-rpmalloc</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-shaderc</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-sse</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-stb</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-tinyexr</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-tinyfd</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-tootle</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-vma</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-vulkan</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-xxhash</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-yoga</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-zstd</artifactId></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-assimp</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-bgfx</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-glfw</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-jemalloc</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-libdivide</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-llvm</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-lmdb</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-lz4</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-meow</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-nanovg</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-nfd</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-nuklear</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-openal</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opengl</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opengles</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-openvr</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-opus</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-ovr</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-par</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-remotery</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-rpmalloc</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-shaderc</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-sse</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-stb</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-tinyexr</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-tinyfd</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-tootle</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-vma</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-xxhash</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-yoga</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.lwjgl</groupId><artifactId>lwjgl-zstd</artifactId><classifier>${lwjgl.natives}</classifier></dependency><dependency><groupId>org.joml</groupId><artifactId>joml</artifactId><version>${joml.version}</version></dependency><dependency><groupId>com.code-disaster.steamworks4j</groupId><artifactId>steamworks4j</artifactId><version>${steamworks4j.version}</version></dependency><dependency><groupId>com.code-disaster.steamworks4j</groupId><artifactId>steamworks4j-server</artifactId><version>${steamworks4j-server.version}</version></dependency></dependencies>第二步：创建类，引入需要的包，设置全局参数
1.创建类
public class TriangleExample {......}2. 包引入
import org.lwjgl.glfw.*;import org.lwjgl.opengl.*;import org.lwjgl.system.MemoryStack;import static org.lwjgl.glfw.GLFW.*;import static org.lwjgl.opengl.GL11.*;import static org.lwjgl.system.MemoryUtil.*;import java.nio.IntBuffer;import java.util.Objects;import java.util.Random;3. 全局参数
// 窗口句柄private long window;// x坐标private float triangleX = 0.0f;// y坐标private float triangleY = 0.0f;// 步长private final float triangleSpeed = 0.05f;第三步：定义一个初始化方法 init()
1. GLFW 错误信息的回调函数
这样做，在发生 GLFW 错误时，错误信息将被打印到标准错误流（System.err）
GLFWErrorCallback.createPrint(System.err).set();2. 初始化 GLFW 库
if (!glfwInit()) { throw new IllegalStateException("Unable to initialize GLFW"); }3. 窗口设置
//设置默认的窗口提示参数glfwDefaultWindowHints();//设置窗口不可见glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);//设置窗口可调整大小glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);//指定窗口宽度int width = 500;//指定窗口高度int height = 500;//创建一个指定大小和标题的窗口。window = glfwCreateWindow(width, height, "OpenGL Triangle Example", NULL, NULL);//如果创建失败，抛出一个运行时异常if (window == NULL) {throw new RuntimeException("Failed to create the GLFW window");}4. 设置键盘回调函数
- 参数说明：
- window: 表示触发键盘事件的窗口句柄。它指定了事件发生的窗口。
- key:表示被按下或释放的键的键码。每个按键都有一个对应的唯一键码，用于标识不同的按键。
- scancode:表示键的扫描码。扫描码是键盘硬件生成的唯一标识符，它与特定的键码相对应。
- action: 表示键盘事件的动作类型。它可以有以下几种取值
- GLFW_PRESS：按下了键。
- GLFW_RELEASE：释放了键。
- GLFW_REPEAT：重复按下了键，通常在按键持续按下时触发。
- mods: 表示与键盘事件同时按下的修饰键（如 Shift、Ctrl、Alt 等），它是一个位字段，通过对特定位进行设置来表示修饰键的状态。
我们这里监听上下左右键，aswd键和一个esc退出键
glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> {if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE) {glfwSetWindowShouldClose(window, true);}if (key == GLFW_KEY_LEFT || key == GLFW_KEY_A) {triangleX -= triangleSpeed;} else if (key == GLFW_KEY_RIGHT || key == GLFW_KEY_D) {triangleX += triangleSpeed;} else if (key == GLFW_KEY_UP || key == GLFW_KEY_W) {triangleY += triangleSpeed;} else if (key == GLFW_KEY_DOWN || key == GLFW_KEY_S) {triangleY -= triangleSpeed;}});5. 创建一个内存栈，窗口定位
try (MemoryStack stack = MemoryStack.stackPush()) {//使用内存栈分配两个整型缓冲区，用于存储窗口的宽度和高度IntBuffer pWidth = stack.mallocInt(1);IntBuffer pHeight = stack.mallocInt(1);//获取窗口的实际大小，并将宽度和高度存储到缓冲区中glfwGetWindowSize(window, pWidth, pHeight);//获取当前主显示器的视频模式GLFWVidMode vidMode = glfwGetVideoMode(glfwGetPrimaryMonitor());//将窗口定位到屏幕中心，根据窗口和屏幕尺寸计算得到位置。glfwSetWindowPos(window, (Objects.requireNonNull(vidMode).width() - pWidth.get(0)) / 2, (vidMode.height() - pHeight.get(0)) / 2);}6. 将指定的窗口设置为当前上下文
在进行 OpenGL 渲染之前，需要将窗口的 OpenGL 上下文设置为当前上下文
以确保 OpenGL 命令在正确的上下文中执行。
glfwMakeContextCurrent(window);7. 设置垂直同步（Vertical Sync）的刷新率
垂直同步是一种同步机制，它将渲染的帧率与显示器的刷新率进行同步
以避免出现画面撕裂（Tearing）的现象。
通过设置刷新率为1，表示与显示器的刷新率保持同步
即每次渲染完一帧后等待显示器垂直同步信号再进行下一帧的渲染。
glfwSwapInterval(1);8. 显示指定的窗口
在创建窗口后，默认是不可见的，通过调用该函数可以将窗口显示出来
glfwShowWindow(window);9. init()代码
private void init() {GLFWErrorCallback.createPrint(System.err).set();if (!glfwInit()) {throw new IllegalStateException("Unable to initialize GLFW");}glfwDefaultWindowHints();glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);int width = 500;int height = 500;window = glfwCreateWindow(width, height, "OpenGL Triangle Example", NULL, NULL);if (window == NULL) {throw new RuntimeException("Failed to create the GLFW window");}glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> {if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE) {glfwSetWindowShouldClose(window, true);}if (key == GLFW_KEY_LEFT || key == GLFW_KEY_A) {triangleX -= triangleSpeed;} else if (key == GLFW_KEY_RIGHT || key == GLFW_KEY_D) {triangleX += triangleSpeed;} else if (key == GLFW_KEY_UP || key == GLFW_KEY_W) {triangleY += triangleSpeed;} else if (key == GLFW_KEY_DOWN || key == GLFW_KEY_S) {triangleY -= triangleSpeed;}});try (MemoryStack stack = MemoryStack.stackPush()) {IntBuffer pWidth = stack.mallocInt(1);IntBuffer pHeight = stack.mallocInt(1);glfwGetWindowSize(window, pWidth, pHeight);GLFWVidMode vidMode = glfwGetVideoMode(glfwGetPrimaryMonitor());glfwSetWindowPos(window, (Objects.requireNonNull(vidMode).width() - pWidth.get(0)) / 2, (vidMode.height() - pHeight.get(0)) / 2);}glfwMakeContextCurrent(window);glfwSwapInterval(1);glfwShowWindow(window);}第四步：定义主循环体loop()
1. 创建并激活 OpenGL 上下文的功能
GL.createCapabilities();2. 设置清空颜色缓冲区的颜色
该行代码将清空颜色设置为黑色
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);3. 主循环
用于不断渲染场景，直到窗口被关闭
while (!glfwWindowShouldClose(window)){......}----------------------------------以下属于循环体中的内容----------------------------------
4. 清空颜色缓冲区和深度缓冲区
将之前设置的清空颜色应用到缓冲区，并清除之前渲染的内容
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);5. 设置坐标系的原点
glLoadIdentity();6. 根据给定的偏移量将当前矩阵进行移动
triangleX和triangleY是控制三角形位置的变量，通过平移变换可以改变三角形的位置
glTranslatef(triangleX, triangleY, 0.0f);7. 创建三角形
这个步骤可以简单理解为：着色–>画画–>着色–>画画–>…
// 定义一个三角形的顶点序列glBegin(GL_TRIANGLES);//设置当前绘制的图元的颜色为红色glColor3f(1.0f, 0.0f, 0.0f);//定义三角形的一个顶点坐标glVertex2f(-0.6f, -0.4f);//设置当前绘制的图元的颜色为绿色glColor3f(0.0f, 1.0f, 0.0f);//定义三角形的第二个顶点坐标glVertex2f(0.6f, -0.4f);//设置当前绘制的图元的颜色为蓝色glColor3f(0.0f, 0.0f, 1.0f);//定义三角形的第三个顶点坐标glVertex2f(0.0f, 0.6f);//结束定义图元的顶点序列glEnd();8. 交换前后缓冲区的内容，用于显示渲染结果
glfwSwapBuffers(window);9. 处理窗口事件，使窗口保持响应状态
例如处理键盘输入、鼠标事件等
glfwPollEvents();10. loop()代码
private void loop() {GL.createCapabilities();glClearColor(0.0f, 0.0f, 0.0f, 0.0f);while (!glfwWindowShouldClose(window)) {glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glLoadIdentity();glTranslatef(triangleX, triangleY, 0.0f);glBegin(GL_TRIANGLES);glColor3f(1.0f, 0.0f, 0.0f);glVertex2f(-0.6f, -0.4f);glColor3f(0.0f, 1.0f, 0.0f);glVertex2f(0.6f, -0.4f);glColor3f(0.0f, 0.0f, 1.0f);glVertex2f(0.0f, 0.6f);glEnd();glfwSwapBuffers(window);glfwPollEvents();}}第五步：定义执行方法run()
1. 执行init()和loop()
init();loop();2. 销毁窗口，关闭程序
用于销毁指定的 GLFW 窗口。它接受一个窗口句柄作为参数，通过调用该函数，可以释放窗口所占用的资源并关闭窗口
glfwDestroyWindow(window);用于终止 GLFW 库。它用于释放 GLFW 所使用的资源，并进行清理操作。在你的程序即将退出时，调用glfwTerminate()是一个好的实践，以确保资源被正确释放。
glfwTerminate();4. run()代码
public void run() {init();loop();glfwDestroyWindow(window);glfwTerminate();}完整代码
import org.lwjgl.glfw.*;import org.lwjgl.opengl.*;import org.lwjgl.system.MemoryStack;import static org.lwjgl.glfw.GLFW.*;import static org.lwjgl.opengl.GL11.*;import static org.lwjgl.system.MemoryUtil.*;import java.nio.IntBuffer;import java.util.Objects;import java.util.Random;public class TriangleExample {private long window;private float triangleX = 0.0f;private float triangleY = 0.0f;private final float triangleSpeed = 0.05f;public void run() {init();loop();glfwDestroyWindow(window);glfwTerminate();}private void init() {GLFWErrorCallback.createPrint(System.err).set();if (!glfwInit()) {throw new IllegalStateException("Unable to initialize GLFW");}glfwDefaultWindowHints();glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);int width = 500;int height = 500;window = glfwCreateWindow(width, height, "OpenGL Triangle Example", NULL, NULL);if (window == NULL) {throw new RuntimeException("Failed to create the GLFW window");}glfwSetKeyCallback(window, (window, key, scancode, action, mods) -> {if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE) {glfwSetWindowShouldClose(window, true);}if (key == GLFW_KEY_LEFT || key == GLFW_KEY_A) {triangleX -= triangleSpeed;} else if (key == GLFW_KEY_RIGHT || key == GLFW_KEY_D) {triangleX += triangleSpeed;} else if (key == GLFW_KEY_UP || key == GLFW_KEY_W) {triangleY += triangleSpeed;} else if (key == GLFW_KEY_DOWN || key == GLFW_KEY_S) {triangleY -= triangleSpeed;}});try (MemoryStack stack = MemoryStack.stackPush()) {IntBuffer pWidth = stack.mallocInt(1);IntBuffer pHeight = stack.mallocInt(1);glfwGetWindowSize(window, pWidth, pHeight);GLFWVidMode vidMode = glfwGetVideoMode(glfwGetPrimaryMonitor());glfwSetWindowPos(window, (Objects.requireNonNull(vidMode).width() - pWidth.get(0)) / 2, (vidMode.height() - pHeight.get(0)) / 2);}glfwMakeContextCurrent(window);glfwSwapInterval(1);glfwShowWindow(window);}private void loop() {GL.createCapabilities();glClearColor(0.0f, 0.0f, 0.0f, 0.0f);while (!glfwWindowShouldClose(window)) {glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glLoadIdentity();glTranslatef(triangleX, triangleY, 0.0f);glBegin(GL_TRIANGLES);glColor3f(1.0f, 0.0f, 0.0f);glVertex2f(-0.6f, -0.4f);glColor3f(0.0f, 1.0f, 0.0f);glVertex2f(0.6f, -0.4f);glColor3f(0.0f, 0.0f, 1.0f);glVertex2f(0.0f, 0.6f);glEnd();glfwSwapBuffers(window);glfwPollEvents();}}public static void main(String[] args) {new TriangleExample().run();}}效果图
画圆
glBegin(GL_TRIANGLE_FAN);float centerX = 0.0f;// 圆心的X坐标float centerY = 0.0f;// 圆心的Y坐标float radius = 0.5f; // 圆的半径int numSegments = 99;// 圆的细分段数glColor3f(0.0f, 2.4f, 5.5f);// 添加圆心顶点0glVertex2f(centerX, centerY);Random random = new Random();// 添加圆上的顶点for (int i = 0; i <= numSegments; i++) {float v = random.nextFloat();float v1 = random.nextFloat();float v2 = random.nextFloat();glColor3f(v, v1, v2);float angle = (float) (2.0 * Math.PI * i / numSegments);float x = centerX + radius * (float) Math.cos(angle);float y = centerY + radius * (float) Math.sin(angle);glVertex2f(x, y);}效果图
记得把三角形的代码注释了，不然可能会出现下面的效果
