Android 如何通过 OpenGL ES 2.0 的片段着色器改变颜色
How to change color by fragment shader of OpenGL ES 2.0 on Android
我正在努力在 Android 上使用实时滤镜实现相机预览。为了做到这一点，我前两天开始研究OpenGL ES 2.0。然而，我不太了解 OpenGL ES 2.0 的结构和语法。然而，由于互联网上的好例子，我能够使用 OpenGL ES 2.0 成功实现灰度相机预览。
今天通过修改那个源码，尝试改变相机预览的颜色。而且……结果很失望。我打算 Seekbar 连续改变相机预览的颜色（准确的亮度）。但是，当我将 Seekbar 的光标向右移动时，所有显示颜色立即变为白色。当我将光标向左移动时，显示也会立即变成黑色。我不知道哪里出了问题，错误代码在哪里。请帮助我...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();
}
}
你的误解是你假设 tex.r 的范围是 0 ~ 255 但实际上它是 0.0 ~ 1.0
你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" +
"}";
对 codetiger 的答案的进一步改进是在语言中使用矢量类型 - 在某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);
}
我正在努力在 Android 上使用实时滤镜实现相机预览。为了做到这一点，我前两天开始研究OpenGL ES 2.0。然而，我不太了解 OpenGL ES 2.0 的结构和语法。然而，由于互联网上的好例子，我能够使用 OpenGL ES 2.0 成功实现灰度相机预览。
今天通过修改那个源码，尝试改变相机预览的颜色。而且……结果很失望。我打算 Seekbar 连续改变相机预览的颜色（准确的亮度）。但是，当我将 Seekbar 的光标向右移动时，所有显示颜色立即变为白色。当我将光标向左移动时，显示也会立即变成黑色。我不知道哪里出了问题，错误代码在哪里。请帮助我...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();
}
}
你的误解是你假设 tex.r 的范围是 0 ~ 255 但实际上它是 0.0 ~ 1.0
你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" +
"}";
对 codetiger 的答案的进一步改进是在语言中使用矢量类型 - 在某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);
}