我很难在Android上使用live-filter实现相机预览。为了做到这一点，我两天前开始研究OpenGL ES 2.0。但是，我不太了解OpenGL ES 2.0的结构和语法。然而，由于来自互联网的好例子，我能够成功使用OpenGL ES 2.0实现灰度级相机预览。
今天，通过修改源代码，我试图改变相机预览的颜色。而......结果令人失望。我打算让Seekbar连续改变相机预览的颜色（确切的亮度）。但是，当我将Seekbar的光标向右移动时，所有显示颜色立刻变为白色。当我将光标向左移动时，显示屏也会变成黑色。我不知道什么是错的，错误的代码在哪里。帮帮我PLZ ......这是我的代码。
MainActivity.java
package com.optimicode.opengltest;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.hardware.Camera;
import android.net.Uri;
import android.opengl.GLSurfaceView;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.SeekBar;
import java.io.File;
import java.io.FileOutputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
public class MainActivity extends Activity {
private FrameLayout mRootLayout;
private SeekBar mSeek;
private MainView mView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mView = new MainView(this);
mView.setOnClickListener(mClick);
mRootLayout = (FrameLayout)findViewById(R.id.layout_root);
mRootLayout.addView(mView, 0);
mSeek = (SeekBar)findViewById(R.id.seek_value);
mSeek.setMax(255);
mSeek.setProgress(128);
mSeek.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
mView.mRenderer.mTest = i - 128;
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
}
@Override
protected void onPause() {
super.onPause();
mView.onPause();
}
@Override
protected void onResume() {
super.onResume();
mView.onResume();
}
View.OnClickListener mClick = new View.OnClickListener() {
@Override
public void onClick(View view) {
mView.mRenderer.takePicture(mPicture);
}
};
Camera.PictureCallback mPicture = new Camera.PictureCallback() {
@Override
public void onPictureTaken(byte[] bytes, Camera camera) {
mView.mRenderer.restartPreview();
String storageDir = Environment.getExternalStorageDirectory().getAbsolutePath()
+ "/" + Environment.DIRECTORY_DCIM + "/Camera";
File dir = new File(storageDir);
if (!dir.exists()) dir.mkdir();
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
String path = storageDir + "/IMG_" + timeStamp + ".jpg";
File file = new File(path);
try {
FileOutputStream fos = new FileOutputStream(file);
fos.write(bytes);
fos.flush();
fos.close();
Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
Uri uri = Uri.parse("file://" + path);
intent.setData(uri);
sendBroadcast(intent);
}
catch (Exception e) {
Log.e("CheckLog", e.getMessage());
return;
}
}
};
}
class MainView extends GLSurfaceView {
MainRenderer mRenderer;
MainView(Context context) {
super(context);
mRenderer = new MainRenderer(this);
setEGLContextClientVersion(2);
setRenderer(mRenderer);
setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
super.surfaceCreated(holder);
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
super.surfaceDestroyed(holder);
mRenderer.close();
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
super.surfaceChanged(holder, format, w, h);
}
}
MainRenderer.java
package com.optimicode.opengltest;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.opengl.GLES11Ext;
import android.opengl.GLES20;
import android.opengl.GLSurfaceView;
import android.util.Log;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
public class MainRenderer implements GLSurfaceView.Renderer, SurfaceTexture.OnFrameAvailableListener {
private final String vertexShaderCode =
"attribute vec2 vPosition;\n" +
"attribute vec2 vTexCoord;\n" +
"varying vec2 texCoord;\n" +
"void main() {\n" +
" texCoord = vTexCoord;\n" +
" gl_Position = vec4(vPosition.x, vPosition.y, 0.0, 1.0);\n" +
"}";
private final String fragmentShaderCode =
"#extension GL_OES_EGL_image_external : require\n" +
"precision mediump float;\n" +
"uniform samplerExternalOES sTexture;\n" +
"uniform float changer;\n" +
"varying vec2 texCoord;\n" +
"void main() {\n" +
" vec4 tex = texture2D(sTexture, texCoord);\n" +
" float cr, cg, cb;\n" +
" if (tex.r + changer > 255.0) cr = 255.0;\n" +
" else if (tex.r + changer < 0.0) cr = 0.0;\n" +
" else cr = tex.r + changer;\n" +
" if (tex.g + changer > 255.0) cg = 255.0;\n" +
" else if (tex.g + changer < 0.0) cg = 0.0;\n" +
" else cg = tex.g + changer;\n" +
" if (tex.b + changer > 255.0) cb = 255.0;\n" +
" else if (tex.b + changer < 0.0) cb = 0.0;\n" +
" else cb = tex.b + changer;\n" +
" gl_FragColor = vec4(cr, cg, cb, tex.a);\n" +
"}";
private int[] hTex;
private FloatBuffer pVertex;
private FloatBuffer pTexCoord;
private int hProgram;
private Camera mCamera;
private SurfaceTexture mSTexture;
private boolean mUpdateST = false;
private MainView mView;
int mTest = 0;
MainRenderer(MainView view) {
mView = view;
float[] vtmp = {-1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f};
float[] ttmp = {1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 0.0f};
pVertex = ByteBuffer.allocateDirect(8*4).order(ByteOrder.nativeOrder()).asFloatBuffer();
pVertex.put(vtmp);
pVertex.position(0);
pTexCoord = ByteBuffer.allocateDirect(8*4).order(ByteOrder.nativeOrder()).asFloatBuffer();
pTexCoord.put(ttmp);
pTexCoord.position(0);
}
public void onSurfaceCreated(GL10 unused, EGLConfig config) {
// String extensions = GLES20.glGetString(GLES20.GL_EXTENSIONS);
// Log.i("CheckLog", "Gl extensions: " + extensions);
// Assert.assertTrue(extensions.contains("OES_EGL_image_external"));
initTex();
mSTexture = new SurfaceTexture(hTex[0]);
mSTexture.setOnFrameAvailableListener(this);
mCamera = Camera.open();
try {
mCamera.setPreviewTexture(mSTexture);
} catch (IOException e) {}
GLES20.glClearColor(1.0f, 1.0f, 1.0f, 1.0f);
hProgram = loadShader(vertexShaderCode, fragmentShaderCode);
}
public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);
Camera.Parameters params = mCamera.getParameters();
params.setPreviewSize(height, width);
params.setPictureSize(height, width);
mCamera.setParameters(params);
mCamera.startPreview();
}
public void onDrawFrame(GL10 unused) {
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
synchronized(this) {
if (mUpdateST) {
mSTexture.updateTexImage();
mUpdateST = false;
}
}
GLES20.glUseProgram(hProgram);
int ph = GLES20.glGetAttribLocation(hProgram, "vPosition");
int tch = GLES20.glGetAttribLocation(hProgram, "vTexCoord");
int th = GLES20.glGetUniformLocation(hProgram, "sTexture");
int mc = GLES20.glGetUniformLocation(hProgram, "changer");
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, hTex[0]);
GLES20.glUniform1i(th, 0);
GLES20.glUniform1f(mc, mTest);
GLES20.glVertexAttribPointer(ph, 2, GLES20.GL_FLOAT, false, 4*2, pVertex);
GLES20.glVertexAttribPointer(tch, 2, GLES20.GL_FLOAT, false, 4*2, pTexCoord);
GLES20.glEnableVertexAttribArray(ph);
GLES20.glEnableVertexAttribArray(tch);
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
GLES20.glFlush();
}
public synchronized void onFrameAvailable(SurfaceTexture st) {
mUpdateST = true;
mView.requestRender();
}
private void initTex() {
hTex = new int[1];
GLES20.glGenTextures(1, hTex, 0);
GLES20.glBindTexture(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, hTex[0]);
GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_S,
GLES20.GL_CLAMP_TO_EDGE);
GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_WRAP_T,
GLES20.GL_CLAMP_TO_EDGE);
GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MIN_FILTER,
GLES20.GL_NEAREST);
GLES20.glTexParameteri(GLES11Ext.GL_TEXTURE_EXTERNAL_OES, GLES20.GL_TEXTURE_MAG_FILTER,
GLES20.GL_NEAREST);
}
public void close() {
mUpdateST = false;
mSTexture.release();
mCamera.stopPreview();
mCamera.release();
mCamera = null;
deleteTex();
}
private void deleteTex() {
GLES20.glDeleteTextures(1, hTex, 0);
}
private static int loadShader(String vertexShaderCode, String fragmentShaderCode) {
int vshader = GLES20.glCreateShader(GLES20.GL_VERTEX_SHADER);
GLES20.glShaderSource(vshader, vertexShaderCode);
GLES20.glCompileShader(vshader);
int[] compiled = new int[1];
GLES20.glGetShaderiv(vshader, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
Log.e("CheckLog", "Could not compile vshader");
Log.v("CheckLog", "Could not compile vshader:" + GLES20.glGetShaderInfoLog(vshader));
GLES20.glDeleteShader(vshader);
vshader = 0;
}
int fshader = GLES20.glCreateShader(GLES20.GL_FRAGMENT_SHADER);
GLES20.glShaderSource(fshader, fragmentShaderCode);
GLES20.glCompileShader(fshader);
GLES20.glGetShaderiv(fshader, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
Log.e("CheckLog", "Could not compile fshader");
Log.v("CheckLog", "Could not compile fshader:" + GLES20.glGetShaderInfoLog(fshader));
GLES20.glDeleteShader(fshader);
fshader = 0;
}
int program = GLES20.glCreateProgram();
GLES20.glAttachShader(program, vshader);
GLES20.glAttachShader(program, fshader);
GLES20.glLinkProgram(program);
return program;
}
public void takePicture(Camera.PictureCallback picture) {
mCamera.takePicture(null, null, null, picture);
}
public void restartPreview() {
mCamera.startPreview();
}
}
答案 0 :(得分：4)
您的误解是您认为tex.r的范围是0 ~ 255但实际上是0.0 ~ 1.0
您的代码应该是这样的
private final String fragmentShaderCode =
"#extension GL_OES_EGL_image_external : require\n" +
"precision mediump float;\n" +
"uniform samplerExternalOES sTexture;\n" +
"uniform float changer;\n" +
"varying vec2 texCoord;\n" +
"void main() {\n" +
" vec4 tex = texture2D(sTexture, texCoord);\n" +
" float cr, cg, cb;\n" +
" cr = clamp(tex.r + changer, 0.0, 1.0);\n" +
" cg = clamp(tex.g + changer, 0.0, 1.0);\n" +
" cb = clamp(tex.b + changer, 0.0, 1.0);\n" +
" gl_FragColor = vec4(cr, cg, cb, tex.a);\n" +
"}";
答案 1 :(得分：1)
codetiger对答案的进一步改进是使用语言中的矢量类型 - 在一些可能更高效的移动GPU上（并且代码更具可读性）。
#extension GL_OES_EGL_image_external : require
precision mediump float;
uniform samplerExternalOES sTexture;
uniform float changer;
varying vec2 texCoord;
void main() {
vec4 tex = texture2D(sTexture, texCoord);
vec3 col = clamp(tex.rgb + changer, 0.0, 1.0);
gl_FragColor = vec4(col, tex.a);
}