org.lwjglb.engine.graph.Transformation类的使用及代码示例

x33g5p2x 于2022-01-30 转载在其他

字(18.3k)|赞(0)|评价(0)|浏览(119)

本文整理了Java中org.lwjglb.engine.graph.Transformation类的一些代码示例，展示了Transformation类的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Transformation类的具体详情如下：
包路径：org.lwjglb.engine.graph.Transformation
类名称：Transformation

Transformation介绍

暂无

代码示例

代码示例来源：origin: lwjglgamedev/lwjglbook

public Renderer() {
  transformation = new Transformation();
  specularPower = 10f;
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public Matrix4f buildModelLightViewMatrix(GameItem gameItem, Matrix4f lightViewMatrix) {
  return buildModelViewMatrix(buildModelMatrix(gameItem), lightViewMatrix);
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void updateLightViewMatrix(Vector3f lightDirection, Vector3f lightPosition) {
  float lightAngleX = (float) Math.toDegrees(Math.acos(lightDirection.z));
  float lightAngleY = (float) Math.toDegrees(Math.asin(lightDirection.x));
  float lightAngleZ = 0;
  Transformation.updateGenericViewMatrix(lightPosition, new Vector3f(lightAngleX, lightAngleY, lightAngleZ), lightViewMatrix);
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void renderScene(Window window, Camera camera, Scene scene) {
  sceneShaderProgram.bind();
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  sceneShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  Matrix4f orthoProjMatrix = transformation.getOrthoProjectionMatrix();
  sceneShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Matrix4f lightViewMatrix = transformation.getLightViewMatrix();
  Matrix4f viewMatrix = transformation.getViewMatrix();
  SceneLight sceneLight = scene.getSceneLight();
  renderLights(viewMatrix, sceneLight);
  sceneShaderProgram.setUniform("fog", scene.getFog());
  sceneShaderProgram.setUniform("texture_sampler", 0);
  sceneShaderProgram.setUniform("normalMap", 1);
  sceneShaderProgram.setUniform("shadowMap", 2);
  // Render each mesh with the associated game Items
  Map<Mesh, List<GameItem>> mapMeshes = scene.getGameMeshes();
  for (Mesh mesh : mapMeshes.keySet()) {
    sceneShaderProgram.setUniform("material", mesh.getMaterial());
    glActiveTexture(GL_TEXTURE2);
    glBindTexture(GL_TEXTURE_2D, shadowMap.getDepthMapTexture().getId());
    mesh.renderList(mapMeshes.get(mesh), (GameItem gameItem) -> {
      Matrix4f modelViewMatrix = transformation.buildModelViewMatrix(gameItem, viewMatrix);
      sceneShaderProgram.setUniform("modelViewMatrix", modelViewMatrix);
      Matrix4f modelLightViewMatrix = transformation.buildModelLightViewMatrix(gameItem, lightViewMatrix);
      sceneShaderProgram.setUniform("modelLightViewMatrix", modelLightViewMatrix);
    }
    );
  }
  sceneShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderSkyBox(Window window, Camera camera, Scene scene) {
  skyBoxShaderProgram.bind();
  skyBoxShaderProgram.setUniform("texture_sampler", 0);
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  skyBoxShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  SkyBox skyBox = scene.getSkyBox();
  Matrix4f viewMatrix = transformation.getViewMatrix();
  viewMatrix.m30(0);
  viewMatrix.m31(0);
  viewMatrix.m32(0);
  Matrix4f modelViewMatrix = transformation.buildModelViewMatrix(skyBox, viewMatrix);
  skyBoxShaderProgram.setUniform("modelViewMatrix", modelViewMatrix);
  skyBoxShaderProgram.setUniform("ambientLight", scene.getSceneLight().getSkyBoxLight());
  scene.getSkyBox().getMesh().render();
  skyBoxShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void renderScene(Window window, Camera camera, Scene scene) {
  sceneShaderProgram.bind();
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  sceneShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  Matrix4f orthoProjMatrix = transformation.getOrthoProjectionMatrix();
  sceneShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Matrix4f lightViewMatrix = transformation.getLightViewMatrix();
  Matrix4f viewMatrix = transformation.getViewMatrix();
  SceneLight sceneLight = scene.getSceneLight();
  renderLights(viewMatrix, sceneLight);
  sceneShaderProgram.setUniform("fog", scene.getFog());
  sceneShaderProgram.setUniform("texture_sampler", 0);
  sceneShaderProgram.setUniform("normalMap", 1);
  sceneShaderProgram.setUniform("shadowMap", 2);
  sceneShaderProgram.setUniform("renderShadow", scene.isRenderShadows() ? 1 : 0);
  renderNonInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  renderInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  sceneShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderChunkInstanced(List<GameItem> gameItems, boolean depthMap, Transformation transformation, Matrix4f viewMatrix, Matrix4f lightViewMatrix) {
    this.modelViewBuffer.clear();
    this.modelLightViewBuffer.clear();

    int i = 0;

    for (GameItem gameItem : gameItems) {
      Matrix4f modelMatrix = transformation.buildModelMatrix(gameItem);
      if (!depthMap) {
        Matrix4f modelViewMatrix = transformation.buildModelViewMatrix(modelMatrix, viewMatrix);
        modelViewMatrix.get(MATRIX_SIZE_FLOATS * i, modelViewBuffer);
      }
      Matrix4f modelLightViewMatrix = transformation.buildModelLightViewMatrix(modelMatrix, lightViewMatrix);
      modelLightViewMatrix.get(MATRIX_SIZE_FLOATS * i, this.modelLightViewBuffer);
      i++;
    }

    glBindBuffer(GL_ARRAY_BUFFER, modelViewVBO);
    glBufferData(GL_ARRAY_BUFFER, modelViewBuffer, GL_DYNAMIC_DRAW);

    glBindBuffer(GL_ARRAY_BUFFER, modelLightViewVBO);
    glBufferData(GL_ARRAY_BUFFER, modelLightViewBuffer, GL_DYNAMIC_DRAW);

    glDrawElementsInstanced(
        GL_TRIANGLES, getVertexCount(), GL_UNSIGNED_INT, 0, gameItems.size());

    glBindBuffer(GL_ARRAY_BUFFER, 0);
  }
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void render(Window window, Camera camera, Scene scene, IHud hud) {
  clear();
  // Render depth map before view ports has been set up
  renderDepthMap(window, camera, scene);
  glViewport(0, 0, window.getWidth(), window.getHeight());
  // Update projection and view atrices once per render cycle
  transformation.updateProjectionMatrix(FOV, window.getWidth(), window.getHeight(), Z_NEAR, Z_FAR);
  transformation.updateViewMatrix(camera);
  renderScene(window, camera, scene);
  renderSkyBox(window, camera, scene);
  
  renderHud(window, hud);
  //renderAxes(camera);
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void renderScene(Window window, Camera camera, Scene scene) {
  sceneShaderProgram.bind();
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  sceneShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  Matrix4f orthoProjMatrix = transformation.getOrthoProjectionMatrix();
  sceneShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Matrix4f lightViewMatrix = transformation.getLightViewMatrix();
  Matrix4f viewMatrix = camera.getViewMatrix();
  SceneLight sceneLight = scene.getSceneLight();
  renderLights(viewMatrix, sceneLight);
  sceneShaderProgram.setUniform("fog", scene.getFog());
  sceneShaderProgram.setUniform("texture_sampler", 0);
  sceneShaderProgram.setUniform("normalMap", 1);
  sceneShaderProgram.setUniform("shadowMap", 2);
  sceneShaderProgram.setUniform("renderShadow", scene.isRenderShadows() ? 1 : 0);
  renderNonInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  renderInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  sceneShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderDepthMap(Window window, Camera camera, Scene scene) {
  if (scene.isRenderShadows()) {
    // Setup view port to match the texture size
    glBindFramebuffer(GL_FRAMEBUFFER, shadowMap.getDepthMapFBO());
    glViewport(0, 0, ShadowMap.SHADOW_MAP_WIDTH, ShadowMap.SHADOW_MAP_HEIGHT);
    glClear(GL_DEPTH_BUFFER_BIT);
    depthShaderProgram.bind();
    DirectionalLight light = scene.getSceneLight().getDirectionalLight();
    Vector3f lightDirection = light.getDirection();
    float lightAngleX = (float) Math.toDegrees(Math.acos(lightDirection.z));
    float lightAngleY = (float) Math.toDegrees(Math.asin(lightDirection.x));
    float lightAngleZ = 0;
    Matrix4f lightViewMatrix = transformation.updateLightViewMatrix(new Vector3f(lightDirection).mul(light.getShadowPosMult()), new Vector3f(lightAngleX, lightAngleY, lightAngleZ));
    DirectionalLight.OrthoCoords orthCoords = light.getOrthoCoords();
    Matrix4f orthoProjMatrix = transformation.updateOrthoProjectionMatrix(orthCoords.left, orthCoords.right, orthCoords.bottom, orthCoords.top, orthCoords.near, orthCoords.far);
    depthShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
    renderNonInstancedMeshes(scene, depthShaderProgram, null, lightViewMatrix);
    renderInstancedMeshes(scene, depthShaderProgram, null, lightViewMatrix);
    // Unbind
    depthShaderProgram.unbind();
    glBindFramebuffer(GL_FRAMEBUFFER, 0);
  }
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderSkyBox(Window window, Camera camera, Scene scene) {
  skyBoxShaderProgram.bind();
  skyBoxShaderProgram.setUniform("texture_sampler", 0);
  // Update projection Matrix
  Matrix4f projectionMatrix = transformation.getProjectionMatrix(FOV, window.getWidth(), window.getHeight(), Z_NEAR, Z_FAR);
  skyBoxShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  SkyBox skyBox = scene.getSkyBox();
  Matrix4f viewMatrix = transformation.getViewMatrix(camera);
  viewMatrix.m30(0);
  viewMatrix.m31(0);
  viewMatrix.m32(0);
  Matrix4f modelViewMatrix = transformation.getModelViewMatrix(skyBox, viewMatrix);
  skyBoxShaderProgram.setUniform("modelViewMatrix", modelViewMatrix);
  skyBoxShaderProgram.setUniform("ambientLight", scene.getSceneLight().getAmbientLight());
      
  scene.getSkyBox().getMesh().render();
  skyBoxShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderHud(Window window, IHud hud) {
  hudShaderProgram.bind();
  Matrix4f ortho = transformation.getOrthoProjectionMatrix(0, window.getWidth(), window.getHeight(), 0);
  for (GameItem gameItem : hud.getGameItems()) {
    Mesh mesh = gameItem.getMesh();
    // Set ortohtaphic and model matrix for this HUD item
    Matrix4f projModelMatrix = transformation.buildOrtoProjModelMatrix(gameItem, ortho);
    hudShaderProgram.setUniform("projModelMatrix", projModelMatrix);
    hudShaderProgram.setUniform("colour", gameItem.getMesh().getMaterial().getAmbientColour());
    hudShaderProgram.setUniform("hasTexture", gameItem.getMesh().getMaterial().isTextured() ? 1 : 0);
    // Render the mesh for this HUD item
    mesh.render();
  }
  hudShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void renderScene(Window window, Camera camera, Scene scene) {
  sceneShaderProgram.bind();
  Matrix4f projectionMatrix = window.getProjectionMatrix();
  sceneShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  Matrix4f orthoProjMatrix = transformation.getOrthoProjectionMatrix();
  sceneShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Matrix4f lightViewMatrix = transformation.getLightViewMatrix();
  Matrix4f viewMatrix = camera.getViewMatrix();
  SceneLight sceneLight = scene.getSceneLight();
  renderLights(viewMatrix, sceneLight);
  sceneShaderProgram.setUniform("fog", scene.getFog());
  sceneShaderProgram.setUniform("texture_sampler", 0);
  sceneShaderProgram.setUniform("normalMap", 1);
  sceneShaderProgram.setUniform("shadowMap", 2);
  sceneShaderProgram.setUniform("renderShadow", scene.isRenderShadows() ? 1 : 0);
  renderNonInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  renderInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  sceneShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderDepthMap(Window window, Camera camera, Scene scene) {
  // Setup view port to match the texture size
  glBindFramebuffer(GL_FRAMEBUFFER, shadowMap.getDepthMapFBO());
  glViewport(0, 0, ShadowMap.SHADOW_MAP_WIDTH, ShadowMap.SHADOW_MAP_HEIGHT);
  glClear(GL_DEPTH_BUFFER_BIT);
  depthShaderProgram.bind();
  DirectionalLight light = scene.getSceneLight().getDirectionalLight();
  Vector3f lightDirection = light.getDirection();
  float lightAngleX = (float)Math.toDegrees(Math.acos(lightDirection.z));
  float lightAngleY = (float)Math.toDegrees(Math.asin(lightDirection.x));
  float lightAngleZ = 0;
  Matrix4f lightViewMatrix = transformation.updateLightViewMatrix(new Vector3f(lightDirection).mul(light.getShadowPosMult()), new Vector3f(lightAngleX, lightAngleY, lightAngleZ));
  DirectionalLight.OrthoCoords orthCoords = light.getOrthoCoords();
  Matrix4f orthoProjMatrix = transformation.updateOrthoProjectionMatrix(orthCoords.left, orthCoords.right, orthCoords.bottom, orthCoords.top, orthCoords.near, orthCoords.far);
  depthShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Map<Mesh, List<GameItem>> mapMeshes = scene.getGameMeshes();
  for (Mesh mesh : mapMeshes.keySet()) {
    mesh.renderList(mapMeshes.get(mesh), (GameItem gameItem) -> {
      Matrix4f modelLightViewMatrix = transformation.buildModelViewMatrix(gameItem, lightViewMatrix);
      depthShaderProgram.setUniform("modelLightViewMatrix", modelLightViewMatrix);
    }
    );
  }
  // Unbind
  depthShaderProgram.unbind();
  glBindFramebuffer(GL_FRAMEBUFFER, 0);
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderHud(Window window, IHud hud) {
  hudShaderProgram.bind();
  Matrix4f ortho = transformation.getOrthoProjectionMatrix(0, window.getWidth(), window.getHeight(), 0);
  for (GameItem gameItem : hud.getGameItems()) {
    Mesh mesh = gameItem.getMesh();
    // Set ortohtaphic and model matrix for this HUD item
    Matrix4f projModelMatrix = transformation.getOrtoProjModelMatrix(gameItem, ortho);
    hudShaderProgram.setUniform("projModelMatrix", projModelMatrix);
    hudShaderProgram.setUniform("colour", gameItem.getMesh().getMaterial().getAmbientColour());
    // Render the mesh for this HUD item
    mesh.render();
  }
  hudShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public Matrix4f buildModelViewMatrix(GameItem gameItem, Matrix4f viewMatrix) {
  Vector3f rotation = gameItem.getRotation();
  modelMatrix.identity().translate(gameItem.getPosition()).                
      rotateX((float)Math.toRadians(-rotation.x)).
      rotateY((float)Math.toRadians(-rotation.y)).
      rotateZ((float)Math.toRadians(-rotation.z)).
      scale(gameItem.getScale());
  return buildModelViewMatrix(modelMatrix, viewMatrix);
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void renderScene(Window window, Camera camera, Scene scene) {
  sceneShaderProgram.bind();
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  sceneShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  Matrix4f orthoProjMatrix = transformation.getOrthoProjectionMatrix();
  sceneShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Matrix4f lightViewMatrix = transformation.getLightViewMatrix();
  Matrix4f viewMatrix = transformation.getViewMatrix();
  SceneLight sceneLight = scene.getSceneLight();
  renderLights(viewMatrix, sceneLight);
  sceneShaderProgram.setUniform("fog", scene.getFog());
  sceneShaderProgram.setUniform("texture_sampler", 0);
  sceneShaderProgram.setUniform("normalMap", 1);
  sceneShaderProgram.setUniform("shadowMap", 2);
  // Render each mesh with the associated game Items
  Map<Mesh, List<GameItem>> mapMeshes = scene.getGameMeshes();
  for (Mesh mesh : mapMeshes.keySet()) {
    sceneShaderProgram.setUniform("material", mesh.getMaterial());
    glActiveTexture(GL_TEXTURE2);
    glBindTexture(GL_TEXTURE_2D, shadowMap.getDepthMapTexture().getId());
    mesh.renderList(mapMeshes.get(mesh), (GameItem gameItem) -> {
      Matrix4f modelViewMatrix = transformation.buildModelViewMatrix(gameItem, viewMatrix);
      sceneShaderProgram.setUniform("modelViewMatrix", modelViewMatrix);
      Matrix4f modelLightViewMatrix = transformation.buildModelLightViewMatrix(gameItem, lightViewMatrix);
      sceneShaderProgram.setUniform("modelLightViewMatrix", modelLightViewMatrix);
    }
    );
  }
  sceneShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderSkyBox(Window window, Camera camera, Scene scene) {
  skyBoxShaderProgram.bind();
  skyBoxShaderProgram.setUniform("texture_sampler", 0);
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  skyBoxShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  SkyBox skyBox = scene.getSkyBox();
  Matrix4f viewMatrix = transformation.getViewMatrix();
  viewMatrix.m30(0);
  viewMatrix.m31(0);
  viewMatrix.m32(0);
  Matrix4f modelViewMatrix = transformation.buildModelViewMatrix(skyBox, viewMatrix);
  skyBoxShaderProgram.setUniform("modelViewMatrix", modelViewMatrix);
  skyBoxShaderProgram.setUniform("ambientLight", scene.getSceneLight().getAmbientLight());
  scene.getSkyBox().getMesh().render();
  skyBoxShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

public void renderScene(Window window, Camera camera, Scene scene) {
  sceneShaderProgram.bind();
  Matrix4f projectionMatrix = transformation.getProjectionMatrix();
  sceneShaderProgram.setUniform("projectionMatrix", projectionMatrix);
  Matrix4f orthoProjMatrix = transformation.getOrthoProjectionMatrix();
  sceneShaderProgram.setUniform("orthoProjectionMatrix", orthoProjMatrix);
  Matrix4f lightViewMatrix = transformation.getLightViewMatrix();
  Matrix4f viewMatrix = transformation.getViewMatrix();
  SceneLight sceneLight = scene.getSceneLight();
  renderLights(viewMatrix, sceneLight);
  sceneShaderProgram.setUniform("fog", scene.getFog());
  sceneShaderProgram.setUniform("texture_sampler", 0);
  sceneShaderProgram.setUniform("normalMap", 1);
  sceneShaderProgram.setUniform("shadowMap", 2);
  sceneShaderProgram.setUniform("renderShadow", scene.isRenderShadows() ? 1 : 0);
  renderNonInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  renderInstancedMeshes(scene, sceneShaderProgram, viewMatrix, lightViewMatrix);
  sceneShaderProgram.unbind();
}

代码示例来源：origin: lwjglgamedev/lwjglbook

private void renderNonInstancedMeshes(Scene scene, boolean depthMap, ShaderProgram shader, Matrix4f viewMatrix, Matrix4f lightViewMatrix) {
  sceneShaderProgram.setUniform("isInstanced", 0);
  // Render each mesh with the associated game Items
  Map<Mesh, List<GameItem>> mapMeshes = scene.getGameMeshes();
  for (Mesh mesh : mapMeshes.keySet()) {
    if (!depthMap) {
      shader.setUniform("material", mesh.getMaterial());
      glActiveTexture(GL_TEXTURE2);
      glBindTexture(GL_TEXTURE_2D, shadowMap.getDepthMapTexture().getId());
    }
    mesh.renderList(mapMeshes.get(mesh), (GameItem gameItem) -> {
      Matrix4f modelMatrix = transformation.buildModelMatrix(gameItem);
      if (!depthMap) {
        Matrix4f modelViewMatrix = transformation.buildModelViewMatrix(modelMatrix, viewMatrix);
        sceneShaderProgram.setUniform("modelViewNonInstancedMatrix", modelViewMatrix);
      }
      Matrix4f modelLightViewMatrix = transformation.buildModelLightViewMatrix(modelMatrix, lightViewMatrix);
      sceneShaderProgram.setUniform("modelLightViewNonInstancedMatrix", modelLightViewMatrix);
      if (gameItem instanceof AnimGameItem) {
        AnimGameItem animGameItem = (AnimGameItem) gameItem;
        AnimatedFrame frame = animGameItem.getCurrentFrame();
        shader.setUniform("jointsMatrix", frame.getJointMatrices());
      }
    }
    );
  }
}

内容来源于网络，如有侵权，请联系作者删除！

相关文章

微信公众号

热门标签

Java query python Node 开发语言 request Util 数据库 Table 后端算法 Logger Message Element Parser

最新文章

关于 ChatGPT 必看的 10 篇论文
浏览(4515) 发布于 2023-02-12
ChatGPT 常见错误原因及解决方案：报错、回答不完整、网络错误等
浏览(8118) 发布于 2023-02-12
如何注册OpenAI&ChatGPT
浏览(3986) 发布于 2023-02-12
chatGPT接入个人微信(国内可用)
浏览(2955) 发布于 2023-02-12
ChatGPT 背后的“功臣”——RLHF 技术详解
浏览(942) 发布于 2023-02-12

Transformation类方法