如何在Android（Java）和OpenGL ES 2.0旋轉

Question

其實Im做這在我的渲染器類的繪製方法：

Matrix.setIdentityM(mMMatrix, 0); 
//  Rotate view 

long time = SystemClock.uptimeMillis()*4000L; 
float angle = .09F*(int)time; 
Matrix.setRotateM(mMMatrix, 0, angle, 1, 0, 0); 
Matrix.rotateM(mMMatrix, 0, -2f, 1, 0, 0); 
//Matrix.scaleM(mMMatrix, 0, 0.01f, 0.01f, 0.01f); 

// Calculate the projection and view transformation 
Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0); 
Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0); 

// Draw Shapes  
obj.draw(mMVPMatrix); 

但它不工作...我心中已經嘗試了一些其他但沒有運氣，對象保持不變，不旋轉。

更新：我改變了代碼，沒有運氣。

 // Clear Screen 
     GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); 


     Matrix.setIdentityM(mMMatrix, 0); 

     // Rotate view 
     Matrix.setRotateM(mMMatrix, 0, angle, 1, 0, 0); 
     //Matrix.scaleM(mMMatrix, 0, 0.01f, 0.01f, 0.01f); 

     // Calculate the projection and view transformation 
     Matrix.multiplyMM(mMVMatrix, 0, mVMatrix, 0, mMMatrix, 0); 
     Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVMatrix, 0); 

     // Draw Shapes  
     obj.draw(mMVPMatrix); 

Answer 1

爲什麼Matrix.rotateM在Matrix.setRotateM之後？第二個禁用第一個。

在這裏，我用我的引擎的僞代碼：

Matrix.setIdentityM(_model_matrix, 0); 

Matrix.setRotateM(_rotation_x_matrix, 0, _angles.getX(), 1, 0, 0); 
Matrix.setRotateM(_rotation_y_matrix, 0, _angles.getY(), 0, 1, 0); 
Matrix.setRotateM(_rotation_z_matrix, 0, _angles.getZ(), 0, 0, 1); 
Matrix.multiplyMM(_model_matrix, 0, _rotation_x_matrix, 0, _model_matrix, 0); 
Matrix.multiplyMM(_model_matrix, 0, _rotation_y_matrix, 0, _model_matrix, 0); 
Matrix.multiplyMM(_model_matrix, 0, _rotation_z_matrix, 0, _model_matrix, 0); 

Matrix.multiplyMM(_modelview_matrix, 0, _view_matrix, 0, _model_matrix, 0); 
Matrix.multiplyMM(_modelviewprojection_matrix, 0, _projection_matrix, 0, _modelview_matrix, 0); 

希望它可以幫助;-)