问题描述
我正在尝试使用 GLSurfaceView 来呈现来自 Camera2 的输出。当设备处于纵向模式时它可以正常工作，但是当旋转到横向时，图片当然是“横向”。
关于如何对输出应用旋转，我已经做了一些环顾四周，但是似乎有多种不同的方法，我希望有一种适合我的简单方法。
这是我的 GLSurfaceView 后代的删节版：
public class DWGLCameraview extends GLSurfaceView implements Renderer,OnFrameAvailableListener {
// Other parts snipped
public void onDrawFrame(GL10 gl) {
mSurfaceTexture.updateTexImage();
float[] mtx = new float[16];
mSurfaceTexture.getTransformMatrix(mtx);
// Can I do something here to apply the rotation?
mDrawer.draw(mtx);
}
}
..还有这个（如果有帮助的话），就是绘图程序 DWGLDrawer 类：
import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.opengl.Matrix;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
public class DWGLDrawer {
private final String vertexshadercode =
"attribute vec4 vPosition;" +
"attribute vec4 inputTextureCoordinate;" +
"uniform mat4 u_xform;\n" +
"varying vec2 textureCoordinate;" +
"void main()" +
"{"+
"gl_Position = vPosition;"+
"textureCoordinate = (u_xform * inputTextureCoordinate).xy;" +
"}";
private final String fragmentshadercode =
"#extension GL_OES_EGL_image_external : require\n"+
"precision mediump float;" +
"varying vec2 textureCoordinate;\n" +
"uniform samplerExternalOES s_texture;\n" +
"void main() {" +
" gl_FragColor = texture2D( s_texture,textureCoordinate );\n" +
"}";
private FloatBuffer vertexBuffer,textureVerticesBuffer;
private ShortBuffer drawListBuffer;
private final int mProgram;
private int mPositionHandle;
private int mTextureCoordHandle;
private short drawOrder[] = { 0,1,2,3 }; // order to draw vertices
// number of coordinates per vertex in this array
private static final int COORDS_PER_VERTEX = 2;
private final int vertexStride = COORDS_PER_VERTEX * 4; // 4 bytes per vertex
private static float squareCoords[] = {
-1.0f,1.0f,-1.0f,};
private static float textureVertices[] = {
0.0f,0.0f,};
private int texture;
private int mTransformlocation;
public DWGLDrawer(int texture) {
this.texture = texture;
// initialize vertex byte buffer for shape coordinates
ByteBuffer bb = ByteBuffer.allocateDirect(squareCoords.length * 4);
bb.order(ByteOrder.nativeOrder());
vertexBuffer = bb.asFloatBuffer();
vertexBuffer.put(squareCoords);
vertexBuffer.position(0);
// initialize byte buffer for the draw list
ByteBuffer dlb = ByteBuffer.allocateDirect(drawOrder.length * 2);
dlb.order(ByteOrder.nativeOrder());
drawListBuffer = dlb.asShortBuffer();
drawListBuffer.put(drawOrder);
drawListBuffer.position(0);
ByteBuffer bb2 = ByteBuffer.allocateDirect(textureVertices.length * 4);
bb2.order(ByteOrder.nativeOrder());
textureVerticesBuffer = bb2.asFloatBuffer();
textureVerticesBuffer.put(textureVertices);
textureVerticesBuffer.position(0);
int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER,vertexshadercode);
int fragmentShader = loadShader(GLES20.GL_FRAGMENT_SHADER,fragmentshadercode);
mProgram = GLES20.glCreateProgram(); // create empty OpenGL ES Program
GLES20.glAttachShader(mProgram,vertexShader); // add the vertex shader to program
GLES20.glAttachShader(mProgram,fragmentShader); // add the fragment shader to program
GLES20.glLinkProgram(mProgram); // creates OpenGL ES program executables
mTransformlocation = GLES20.glGetUniformlocation(mProgram,"u_xform");
}
public void draw(float[] mtx) {
GLES20.gluseProgram(mProgram);
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES,texture);
GLES20.gluniformMatrix4fv(mTransformlocation,false,mtx,0);
// get handle to vertex shader's vPosition member
int positionHandle = GLES20.glGetAttribLocation(mProgram,"vPosition");
// Enable a handle to the triangle vertices
GLES20.glEnabLevertexAttribArray(positionHandle);
// Prepare the <insert shape here> coordinate data
GLES20.glVertexAttribPointer(positionHandle,COORDS_PER_VERTEX,GLES20.GL_FLOAT,vertexStride,vertexBuffer);
int textureCoordHandle = GLES20.glGetAttribLocation(mProgram,"inputTextureCoordinate");
GLES20.glEnabLevertexAttribArray(textureCoordHandle);
// textureVerticesBuffer.clear();
// textureVerticesBuffer.put( transformTextureCoordinates( textureVertices,mtx ));
// textureVerticesBuffer.position(0);
GLES20.glVertexAttribPointer(textureCoordHandle,textureVerticesBuffer);
GLES20.glDrawElements(GLES20.GL_TRIANGLES,drawOrder.length,GLES20.GL_UNSIGNED_SHORT,drawListBuffer);
// disable vertex array
GLES20.gldisabLevertexAttribArray(positionHandle);
GLES20.gldisabLevertexAttribArray(textureCoordHandle);
}
private int loadShader(int type,String shadercode) {
// create a vertex shader type (GLES20.GL_VERTEX_SHADER)
// or a fragment shader type (GLES20.GL_FRAGMENT_SHADER)
int shader = GLES20.glCreateShader(type);
// add the source code to the shader and compile it
GLES20.glShaderSource(shader,shadercode);
GLES20.glCompileShader(shader);
return shader;
}
private float[] transformTextureCoordinates( float[] coords,float[] matrix) {
float[] result = new float[ coords.length ];
float[] vt = new float[4];
for ( int i = 0 ; i < coords.length ; i += 2 ) {
float[] v = { coords[i],coords[i+1],1 };
Matrix.multiplyMV(vt,matrix,v,0);
result[i] = vt[0];
result[i+1] = vt[1];
}
return result;
}
}
根据我在 onDrawFrame 中的评论，我认为我可以在那里应用轮换。我试过这个：
if (mRotation > 0)
Matrix.rotateM(mtx,mRotation,0f,-1f);
（mRotation 是以度为单位的旋转值）
然而，这导致了一张难以理解的图片，所以我认为这是完全错误的，或者我需要做其他事情
请记住，我使用的是 Camera2，所以 setdisplayOrientation（来自 Camera）不是一个选项
编辑
我现在已经包含了 DWGLDrawer 的整个声明，并添加到描述中
解决方法
一般来说，您的方法应该是正确的（假设 mRotation 以度为单位，并且基于 Display.getRotation() 之类的东西来确定您的 UI 方向 - 请注意，getRotation 不返回度数，因此必须调整该值） .
但是，这里没有您的着色器代码，因此很难说您是否以与您使用的 rotateM 调用兼容的方式使用 mTransformLocation。因此，您可能只需要调试您看到的矩阵值、rotate 调用的作用等，以找出数学问题在哪里。不幸的是，在处理 EGL（或任何地方，真的）中的转换时很常见。