Langsung ke konten

Paling sering dikunjungi

Terakhir dikunjungi

navigation

Adding Motion

This lesson teaches you to

  1. Rotate a Shape
  2. Enable Continuous Rendering

You should also read

Download the sample

OpenGLES.zip

Drawing objects on screen is a pretty basic feature of OpenGL, but you can do this with other Android graphics framwork classes, including Canvas and Drawable objects. OpenGL ES provides additional capabilities for moving and transforming drawn objects in three dimensions or in other unique ways to create compelling user experiences.

In this lesson, you take another step forward into using OpenGL ES by learning how to add motion to a shape with rotation.

Rotate a Shape

Rotating a drawing object with OpenGL ES 2.0 is relatively simple. In your renderer, create another transformation matrix (a rotation matrix) and then combine it with your projection and camera view transformation matrices:

private float[] mRotationMatrix = new float[16];
public void onDrawFrame(GL10 gl) {
    float[] scratch = new float[16];

    ...

    // Create a rotation transformation for the triangle
    long time = SystemClock.uptimeMillis() % 4000L;
    float angle = 0.090f * ((int) time);
    Matrix.setRotateM(mRotationMatrix, 0, angle, 0, 0, -1.0f);

    // Combine the rotation matrix with the projection and camera view
    // Note that the mMVPMatrix factor *must be first* in order
    // for the matrix multiplication product to be correct.
    Matrix.multiplyMM(scratch, 0, mMVPMatrix, 0, mRotationMatrix, 0);

    // Draw triangle
    mTriangle.draw(scratch);
}

If your triangle does not rotate after making these changes, make sure you have commented out the GLSurfaceView.RENDERMODE_WHEN_DIRTY setting, as described in the next section.

Enable Continuous Rendering

If you have diligently followed along with the example code in this class to this point, make sure you comment out the line that sets the render mode only draw when dirty, otherwise OpenGL rotates the shape only one increment and then waits for a call to requestRender() from the GLSurfaceView container:

public MyGLSurfaceView(Context context) {
    ...
    // Render the view only when there is a change in the drawing data.
    // To allow the triangle to rotate automatically, this line is commented out:
    //setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
}

Unless you have objects changing without any user interaction, it’s usually a good idea have this flag turned on. Be ready to uncomment this code, because the next lesson makes this call applicable once again.

Situs ini menggunakan cookies untuk menyimpan preferensi Anda tentang bahasa di situs tertentu dan opsi tampilan.

Dapatkan berita dan tips terbaru dari developer Android yang akan membantu Anda mencapai kesuksesan di Google Play.

* Wajib Diisi

Hore!

Ikuti Google Developers di WeChat

Buka situs ini dalam bahasa ?

Anda meminta halaman dalam bahasa , namun preferensi bahasa untuk situs ini adalah .

Ingin mengubah preferensi bahasa dan mengakses situs ini dalam bahasa ? Jika nanti Anda ingin mengubah preferensi bahasa, gunakan menu bahasa di bagian bawah setiap halaman.

Kelas ini memerlukan tingkat API atau yang lebih tinggi

Dokumen ini tersembunyi karena level API yang Anda pilih untuk dokumentasi ini adalah . Anda dapat mengubah level API dokumentasi dengan pemilih di atas menu navigasi sebelah kiri.

Untuk informasi lebih lanjut tentang menentukan level API yang diperlukan aplikasi Anda, baca Mendukung Versi Platform Yang Berbeda.

Take a short survey?
Help us improve the Android developer experience. (April 2018 — Developer Survey)