OpenGL ES 2.0 在横向模式下切屏

Question

我开始学习 OpenGL，正在使用以下网站：http://www.learnopengles.com/android-lesson-one-getting-started/

但这部分我似乎遇到了问题（在纵向模式下工作正常）：

private float[] mViewMatrix = new float[16];

/** Store the projection matrix. This is used to project the scene onto a 2D viewport. */
private float[] mProjectionMatrix = new float[16];

/** Allocate storage for the final combined matrix. This will be passed into the shader program. */
private float[] mMVPMatrix = new float[16];

/** This will be used to pass in the transformation matrix. */
private int mMVPMatrixHandle;

/** This will be used to pass in model position information. */
private int mPositionHandle;

/** This will be used to pass in model color information. */
private int mColorHandle;

/** How many bytes per float. */
private final int mBytesPerFloat = 4;

/** How many elements per vertex. */
private final int mStrideBytes = 7 * mBytesPerFloat;    

/** Size of the position data in elements. */
private final int mPositionDataSize = 3;

/** Offset of the color data. */
private final int mColorOffset = 3;

/** Size of the color data in elements. */
private final int mColorDataSize = 4;

public void onSurfaceChanged(GL10 gl, int width, int height)
{       
    GLES20.glViewport(0, 0, width, height);

    // Create a new perspective projection matrix. The height will stay the same
    // while the width will vary as per aspect ratio.
    final float ratio = (float) width / height;
    final float left = -ratio;
    final float right = ratio;
    final float bottom = -1.0f;
    final float top = 1.0f;
    final float near = 1.0f;
    final float far = 10.0f;

    System.out.println("Height: " + height);
    System.out.println("Width: " + width);

    Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far);
}

public void onDrawFrame(GL10 gl)
{
        final float eyeX = 0.0f; 
        final float eyeY = 0.0f;
        final float eyeZ = 1.5f;

        final float lookY = 0.0f; //Y direction of what user see
        final float lookZ = -5.0f;  //Z direction of what user see

        // Set our up vector. This is where our head would be pointing were we holding the camera.
        final float upX = 0.0f;
        final float upY = 1.0f;
        final float upZ = 0.0f;

        GLES20.glClearColor(red, green, blue, clearcoloralpha);
        GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);    
        Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, xax, lookY, lookZ, upX, upY, upZ);

        // Draw the triangle facing straight on.        
        for(int i = 0; i < Triangles.size(); i++)
        {
            Matrix.setIdentityM(Triangles.get(i).getModelMatrix(), 0);

            if(Triangles.get(i).Rotate())
            {
                Triangles.get(i).rotation = (360.0f / 10000.0f) * ((int) Triangles.get(i).last);
                Triangles.get(i).last+=20;

                //Rotates the matrix by rotation degrees
                Matrix.rotateM(Triangles.get(i).getModelMatrix(), 0, Triangles.get(i).rotation, 0.0f, 0.0f, 1.0f);
            }
            else
                Matrix.rotateM(Triangles.get(i).getModelMatrix(), 0, Triangles.get(i).rotation, 0.0f, 0.0f, 1.0f);

            drawTriangle(Triangles.get(i).getFloatBuffer(),Triangles.get(i));
        }
}

private void drawTriangle(final FloatBuffer aTriangleBuffer, Triangle tri)
{       
    aTriangleBuffer.position(0);
    GLES20.glVertexAttribPointer(mPositionHandle, tri.DataSize, GLES20.GL_FLOAT, false, mStrideBytes, aTriangleBuffer);                
    GLES20.glEnableVertexAttribArray(mPositionHandle);        

    aTriangleBuffer.position(3);
    GLES20.glVertexAttribPointer(mColorHandle, tri.ColorDataSize, GLES20.GL_FLOAT, false, mStrideBytes, aTriangleBuffer);                
    GLES20.glEnableVertexAttribArray(mColorHandle);

    Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, tri.getModelMatrix(), 0);
    Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);

    GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);
    GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);     
}

但是，当我尝试在横向模式下（向左或向右）移动三角形时，当将三角形移动到远处的一侧时，三角形会被“截断”（不显示整个三角形）。似乎他们被表演了，就好像他们在屏幕外一样，而实际上并非如此。如前所述，它在纵向模式下似乎可以正常工作。

横向模式下的高度为 752，宽度为 1280（Galaxy Tab 2）。

这和这里设置的项目矩阵有关系吗？

感谢您的帮助！

Answer 1

你是对的，问题是你在移动你的相机：D

xax 应该保持为 0.0f

Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, xax, lookY, lookZ, upX, upY, upZ);