我开始学习 OpenGL，并使用以下网站： http: //www.learnopengles.com/android-lesson-one-getting-started/
但似乎我在这部分遇到了问题（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移动一个三角形（向左或向右）时，当将它们移动到远处的一侧时，三角形会被“切断”（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，它似乎在纵向模式下工作正常。
横向模式下的高度为 752，宽度为 1280（Galaxy Tab 2）。
这是否与此处设置的项目矩阵有关？
谢谢你的帮助！