我正在尝试使用新的 EffectFactory/Effect 为屏幕外的图像添加效果（即帧缓冲区）。我查看了 SDK 中提供的HelloEffects.java 示例，并且我已经尝试过了，它可以工作。除了它显然使用 GLSurfaceView 而这不是我想要的。
所以我使用了tests/effect/src/android/effect/cts/GLEnv.java来设置 EGL 的东西，我还从 HelloEffects 示例中获取了 TextureRenderer.java 和 GLToolbox。把它们全部捣碎，我得到了下面的代码。
（附带说明一下，我还尝试了 tests/media/src/android/media/cts/OutputSurface.java 来设置 EGL 的东西，我得到了完全相同的结果。）
当我运行它时，我得到的图像只是统一的蓝色。这对应于我用蓝色做的 glClear。这至少在某种程度上证明了像素正在渲染到帧缓冲区，glReadPixels 正在查看这些像素并且位图输出正在工作。
但是为什么纹理没有显示出来？原始纹理和应用效果的纹理均未显示。也没有检测到 GL 错误。
我已经将代码缩减为一个可以复制/粘贴到 Eclipse 中并运行的单个文件工作示例。显然根据您的需要修改输入和输出图像路径。
在 Nexus 10 / Android 4.3 以及模拟器上测试。结果相同。
import java.io.FileOutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLContext;
import javax.microedition.khronos.egl.EGLDisplay;
import javax.microedition.khronos.egl.EGLSurface;
import android.media.effect.Effect;
import android.media.effect.EffectContext;
import android.media.effect.EffectFactory;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.opengl.GLES20;
import android.opengl.GLUtils;
public class MainActivity extends Activity
{
private int[] mTextures = new int[2];
private EffectContext mEffectContext;
private Effect mEffect;
private TextureRenderer mTexRenderer = new TextureRenderer();
private int mImageWidth;
private int mImageHeight;
final static String imageFileOut = "/data/local/out.png";
final static String imageFileIn = "/data/local/lol.png";
private GLEnv mEnv;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mEnv = new GLEnv();
mEnv.makeCurrent();
mEffectContext = EffectContext.createWithCurrentGlContext();
mTexRenderer.init();
loadTextures();
initAndapplyEffect();
renderResult();
saveBitmap();
}
void saveBitmap()
{
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
ByteBuffer pixelBuffer = ByteBuffer.allocateDirect(mImageWidth * mImageHeight * 4).order(ByteOrder.nativeOrder());
GLES20.glReadPixels(0, 0, mImageWidth, mImageHeight, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, pixelBuffer);
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
mEnv.checkForEGLErrors("store Pixels");
Bitmap bitmap = Bitmap.createBitmap(mImageWidth, mImageHeight, Bitmap.Config.ARGB_8888);
bitmap.copyPixelsFromBuffer(pixelBuffer);
try
{
FileOutputStream fos = new FileOutputStream(imageFileOut);
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();
} catch (Exception e) { e.printStackTrace(); }
}
private void initAndapplyEffect()
{
EffectFactory effectFactory = mEffectContext.getFactory();
if (mEffect != null)
{
mEffect.release();
}
mEffect = effectFactory.createEffect(EffectFactory.EFFECT_BRIGHTNESS);
mEffect.setParameter("brightness", 2.0f);
mEffect.apply(mTextures[0], mImageWidth, mImageHeight, mTextures[1]);
}
private int loadTextures()
{
// Generate textures
GLES20.glGenTextures(2, mTextures, 0);
// Load input bitmap
Bitmap bitmap = BitmapFactory.decodeFile(imageFileIn);
mImageWidth = bitmap.getWidth();
mImageHeight = bitmap.getHeight();
mTexRenderer.updateTextureSize(mImageWidth, mImageHeight);
// Upload to texture
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextures[0]);
GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0);
// Set texture parameters
GLToolbox.initTexParams();
return mTextures[0];
}
private void renderResult()
{
mTexRenderer.renderTexture(mTextures[1]);
//mTexRenderer.renderTexture(mTextures[0]);
}
public class GLEnv {
private EGLContext mEGLContext;
private EGLSurface mEGLSurface;
private EGLDisplay mEGLDisplay;
private EGLConfig mEGLConfig;
private static final int EGL_CONTEXT_CLIENT_VERSION = 0x3098;
private static final int EGL_OPENGL_ES2_BIT = 0x0004;
public GLEnv() {
EGL10 egl = (EGL10)EGLContext.getEGL();
mEGLDisplay = egl.eglGetDisplay(EGL10.EGL_DEFAULT_DISPLAY);
checkForEGLErrors("eglGetDisplay");
int[] version = new int[2];
egl.eglInitialize(mEGLDisplay, version);
int[] configSpec = {
EGL10.EGL_SURFACE_TYPE, EGL10.EGL_PBUFFER_BIT,
EGL10.EGL_RED_SIZE, 8,
EGL10.EGL_GREEN_SIZE, 8,
EGL10.EGL_BLUE_SIZE, 8,
EGL10.EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
EGL10.EGL_NONE
};
EGLConfig[] configs = new EGLConfig[1];
int[] num_config = new int[1];
egl.eglChooseConfig(mEGLDisplay, configSpec, configs, 1, num_config);
checkForEGLErrors("eglChooseConfig");
if (num_config[0] < 1) {
throw new RuntimeException("Could not find a suitable config for EGL context!");
}
mEGLConfig = configs[0];
int[] attribs = { EGL_CONTEXT_CLIENT_VERSION, 2, EGL10.EGL_NONE };
mEGLContext = egl.eglCreateContext(mEGLDisplay, mEGLConfig, EGL10.EGL_NO_CONTEXT, attribs);
checkForEGLErrors("eglCreateContext");
int[] surfaceSize = { EGL10.EGL_WIDTH, 1920, EGL10.EGL_HEIGHT, 1080, EGL10.EGL_NONE };
mEGLSurface = egl.eglCreatePbufferSurface(mEGLDisplay, mEGLConfig, surfaceSize);
checkForEGLErrors("eglCreatePbufferSurface");
}
public void makeCurrent() {
EGL10 egl = (EGL10)EGLContext.getEGL();
egl.eglMakeCurrent(mEGLDisplay, mEGLSurface, mEGLSurface, mEGLContext);
checkForEGLErrors("eglMakeCurrent");
}
public void checkForEGLErrors(String operation) {
EGL10 egl = (EGL10)EGLContext.getEGL();
int error = egl.eglGetError();
if (error != EGL10.EGL_SUCCESS) {
throw new RuntimeException("Operation '" + operation + "' caused EGL error: " + error);
}
}
}
private static final float[] TEX_VERTICES = {
0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f
};
private static final float[] POS_VERTICES = {
-1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f
};
public class TextureRenderer {
private int mProgram;
private int mTexSamplerHandle;
private int mTexCoordHandle;
private int mPosCoordHandle;
private FloatBuffer mTexVertices;
private FloatBuffer mPosVertices;
private int mViewWidth;
private int mViewHeight;
private int mTexWidth;
private int mTexHeight;
private static final String VERTEX_SHADER =
"attribute vec4 a_position;\n" +
"attribute vec2 a_texcoord;\n" +
"varying vec2 v_texcoord;\n" +
"void main() {\n" +
" gl_Position = a_position;\n" +
" v_texcoord = a_texcoord;\n" +
"}\n";
private static final String FRAGMENT_SHADER =
"precision mediump float;\n" +
"uniform sampler2D tex_sampler;\n" +
"varying vec2 v_texcoord;\n" +
"void main() {\n" +
" gl_FragColor = texture2D(tex_sampler, v_texcoord);\n" +
"}\n";
private static final int FLOAT_SIZE_BYTES = 4;
public void init() {
// Create program
mProgram = GLToolbox.createProgram(VERTEX_SHADER, FRAGMENT_SHADER);
// Bind attributes and uniforms
mTexSamplerHandle = GLES20.glGetUniformLocation(mProgram,
"tex_sampler");
mTexCoordHandle = GLES20.glGetAttribLocation(mProgram, "a_texcoord");
mPosCoordHandle = GLES20.glGetAttribLocation(mProgram, "a_position");
// Setup coordinate buffers
mTexVertices = ByteBuffer.allocateDirect(
TEX_VERTICES.length * FLOAT_SIZE_BYTES)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mTexVertices.put(TEX_VERTICES).position(0);
mPosVertices = ByteBuffer.allocateDirect(
POS_VERTICES.length * FLOAT_SIZE_BYTES)
.order(ByteOrder.nativeOrder()).asFloatBuffer();
mPosVertices.put(POS_VERTICES).position(0);
}
public void tearDown() {
GLES20.glDeleteProgram(mProgram);
}
public void updateTextureSize(int texWidth, int texHeight) {
mTexWidth = texWidth;
mTexHeight = texHeight;
computeOutputVertices();
}
public void updateViewSize(int viewWidth, int viewHeight) {
mViewWidth = viewWidth;
mViewHeight = viewHeight;
computeOutputVertices();
}
public void renderTexture(int texId) {
// Bind default FBO
GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0);
// Use our shader program
GLES20.glUseProgram(mProgram);
GLToolbox.checkGlError("glUseProgram");
// Set viewport
GLES20.glViewport(0, 0, mViewWidth, mViewHeight);
GLToolbox.checkGlError("glViewport");
// Disable blending
GLES20.glDisable(GLES20.GL_BLEND);
// Set the vertex attributes
GLES20.glVertexAttribPointer(mTexCoordHandle, 2, GLES20.GL_FLOAT, false,
0, mTexVertices);
GLES20.glEnableVertexAttribArray(mTexCoordHandle);
GLES20.glVertexAttribPointer(mPosCoordHandle, 2, GLES20.GL_FLOAT, false,
0, mPosVertices);
GLES20.glEnableVertexAttribArray(mPosCoordHandle);
GLToolbox.checkGlError("vertex attribute setup");
// Set the input texture
GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
GLToolbox.checkGlError("glActiveTexture");
GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texId);
GLToolbox.checkGlError("glBindTexture");
GLES20.glUniform1i(mTexSamplerHandle, 0);
// Draw
GLES20.glClearColor(0.0f, 0.0f, 0.5f, 1.0f);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
}
private void computeOutputVertices() {
if (mPosVertices != null) {
float imgAspectRatio = mTexWidth / (float)mTexHeight;
float viewAspectRatio = mViewWidth / (float)mViewHeight;
float relativeAspectRatio = viewAspectRatio / imgAspectRatio;
float x0, y0, x1, y1;
if (relativeAspectRatio > 1.0f) {
x0 = -1.0f / relativeAspectRatio;
y0 = -1.0f;
x1 = 1.0f / relativeAspectRatio;
y1 = 1.0f;
} else {
x0 = -1.0f;
y0 = -relativeAspectRatio;
x1 = 1.0f;
y1 = relativeAspectRatio;
}
float[] coords = new float[] { x0, y0, x1, y0, x0, y1, x1, y1 };
mPosVertices.put(coords).position(0);
}
}
}
public static class GLToolbox {
public static int loadShader(int shaderType, String source) {
int shader = GLES20.glCreateShader(shaderType);
if (shader != 0) {
GLES20.glShaderSource(shader, source);
GLES20.glCompileShader(shader);
int[] compiled = new int[1];
GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
if (compiled[0] == 0) {
String info = GLES20.glGetShaderInfoLog(shader);
GLES20.glDeleteShader(shader);
shader = 0;
throw new RuntimeException("Could not compile shader " +
shaderType + ":" + info);
}
}
return shader;
}
public static int createProgram(String vertexSource,
String fragmentSource) {
int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
if (vertexShader == 0) {
return 0;
}
int pixelShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
if (pixelShader == 0) {
return 0;
}
int program = GLES20.glCreateProgram();
if (program != 0) {
GLES20.glAttachShader(program, vertexShader);
checkGlError("glAttachShader");
GLES20.glAttachShader(program, pixelShader);
checkGlError("glAttachShader");
GLES20.glLinkProgram(program);
int[] linkStatus = new int[1];
GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linkStatus,
0);
if (linkStatus[0] != GLES20.GL_TRUE) {
String info = GLES20.glGetProgramInfoLog(program);
GLES20.glDeleteProgram(program);
program = 0;
throw new RuntimeException("Could not link program: " + info);
}
}
return program;
}
public static void checkGlError(String op) {
int error;
while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
throw new RuntimeException(op + ": glError " + error);
}
}
public static void initTexParams() {
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D,
GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S,
GLES20.GL_CLAMP_TO_EDGE);
GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T,
GLES20.GL_CLAMP_TO_EDGE);
}
}
}