一、关于GLSurfaceView
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编写OpenGL ES应用的起始点是从类GLSurfaceView开始，GLSurfaceView是OpenGL ES API的核心类，在Android上使用Opengl操作的对象是GLSurfaceView，这是一个继承自View的扩展。
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实现两个必须调用的方法
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setRenderer()：设置renderer
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setEGLContextClientVersion()：设置OpenGL版本号
public class DefaultSurfaceView extends BaseSurfaceView { public DefaultSurfaceView(Context context) { super(context); setEGLContextClientVersion(); setRenderer(); } @Override protected void setRenderer() { DefaultRenderer defaultRenderer = new DefaultRenderer(mContext); defaultRenderer.setBitmap(getBitmap()); setRenderer(defaultRenderer); setRenderMode(RENDERMODE_WHEN_DIRTY); } @Override protected void setEGLContextClientVersion() { setEGLContextClientVersion(2); } }
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二、关于GLSurfaceView.Renderer
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在Android上使用GLSurfaceView来显示并完成图片的渲染，实现渲染需要实现GLSurfaceView.Render接口
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三个接口方法描述：
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onDrawFrame(GL10 gl) ，该方法按照一定的刷新频率反复执行，定义实际的绘图操作；
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onSurfaceCreated(GL10 gl, EGLConfig config)，在创建SurfaceView的时候执行，主要用来设置一些绘制时不常变化的参数，比如：背景色，是否打开 z-buffer等。
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onSurfaceChanged(GL10 gl, int width, int height)，该方法在窗口重绘的时候执行，如果设备支持屏幕横向和纵向切换，这个方法将发生在横向<->纵向互换时。此时可以重新设置绘制的纵横比率。；
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public class DefaultRenderer extends BaseRenderer {
@Override
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
super.onSurfaceCreated(gl, config);
// 创建可以绘制纹理的基类Filter
defaultFilter = new DefaultFilter(mContext);
videoBuffer = CoordinateHelper.calculateDefaultBuffer();
// 创建纹理ID，如果频繁调用onDrawFrame(),则不可将ID创建放在其中，不及时销毁会爆内存的；
defaultTextureId = ShaderHelper.createTexture(GLES20.GL_TEXTURE_2D, bitmap);
}
@Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
super.onSurfaceChanged(gl, width, height);
calculateVertexMatrix();
}
private void calculateVertexMatrix() {
Matrix.setIdentityM(vertexMatrix, 0);
float bmpRatio = bitmap.getWidth() * 1.0f / bitmap.getHeight();
float viewRatio = mViewWidth * 1.0f / mViewHeight;
if (viewRatio < bmpRatio){
// 齐高放大宽
float scale = bmpRatio / viewRatio;
Matrix.scaleM(vertexMatrix, 0, scale, -1.0f, 1.0f);
}else{
// 齐宽放大高
float scale = viewRatio / bmpRatio;
Matrix.scaleM(vertexMatrix, 0, 1.0f, -scale, 1.0f);
}
}
@Override
public void onDrawFrame(GL10 gl) {
super.onDrawFrame(gl);
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT);
GLES20.glViewport(0, 0, mViewWidth, mViewHeight);
if (defaultFilter != null) {
defaultFilter.onDraw(vertexMatrix, ShaderHelper.IDENTITY_MATRIX,
defaultTextureId, videoBuffer);
}
}
}
三、关于Filter框架
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在项目中开发为了复用性更强，都要封装自己的通用框架，每个元素图层就是一个Filter。onDrawFrame中可能同时绘制很多元素，如背景、带美颜和滤镜效果的图片、前景、水印等，每一个元素对应一个Filter，方便图层初始和管理。
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Fitler 封装的绘制步骤：
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构造函数，创建Shader程序，获取句柄。可以有子类传入着色器，也可使用默认着色器；
public AbstractFilter(Context context) { mContext = context; mProgramHandle = createProgram(context); checkProgram(); } public AbstractFilter(Context context, int programHandle) { mContext = context; mProgramHandle = programHandle; checkProgram(); } public AbstractFilter(Context context, @RawRes int vertexSourceRawId, @RawRes int fragmentSourceRawId) { mContext = context; mProgramHandle = ShaderHelper.createProgram(context, vertexSourceRawId, fragmentSourceRawId); checkProgram(); } public AbstractFilter(Context context, String vertexSource, String fragmentSource) { mContext = context; mProgramHandle = ShaderHelper.createProgram(vertexSource, fragmentSource); checkProgram(); } protected int createProgram(Context context) { return ShaderHelper.createProgram(context, R.raw.base_vertex_shader, R.raw.base_fragment_filter); }-
获取着色器中定义的属性句柄;
protected void getGLSLValues() { aPositionLoc = GLES20.glGetAttribLocation(mProgramHandle, "aPosition"); aTextureCoordLoc = GLES20.glGetAttribLocation(mProgramHandle, "aTextureCoord"); uMVPMatrixLoc = GLES20.glGetUniformLocation(mProgramHandle, "uMVPMatrix"); uTexMatrixLoc = GLES20.glGetUniformLocation(mProgramHandle, "uTexMatrix"); mTextureLoc = GLES20.glGetUniformLocation(mProgramHandle, "sourceImage"); }-
使用Program
protected void useProgram() { GLES20.glUseProgram(mProgramHandle); }-
将句柄和纹理进行绑定
protected void bindTexture(int textureId){ GLES20.glActiveTexture(GLES20.GL_TEXTURE0); GLES20.glBindTexture(getTextureTarget(), textureId); GLES20.glUniform1i(mTextureLoc, 0); }-
为属性句柄赋值
protected void bindGLSLValues(float[] mvpMatrix, FloatBuffer vertexBuffer, int coordsPerVertex, int vertexStride, float[] texMatrix, FloatBuffer texBuffer, int texStride) { GLES20.glUniformMatrix4fv(uMVPMatrixLoc, 1, false, mvpMatrix, 0); GLES20.glUniformMatrix4fv(uTexMatrixLoc, 1, false, texMatrix, 0); GLES20.glEnableVertexAttribArray(aPositionLoc); GLES20.glVertexAttribPointer(aPositionLoc, coordsPerVertex, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer); GLES20.glEnableVertexAttribArray(aTextureCoordLoc); GLES20.glVertexAttribPointer(aTextureCoordLoc, 2, GLES20.GL_FLOAT, false, texStride, texBuffer); }-
绘制
protected void drawArrays(int firstVertex, int vertexCount) { GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, firstVertex, vertexCount); }-
将属性句柄解绑释放
protected void unbindGLSLValues() { GLES20.glDisableVertexAttribArray(aPositionLoc); GLES20.glDisableVertexAttribArray(aTextureCoordLoc); }-
将纹理句柄解绑
protected void unbindTexture() { GLES20.glBindTexture(getTextureTarget(), 0); }-
释放Program
protected void disuseProgram() { GLES20.glUseProgram(0); } public void releaseProgram() { GLES20.glDeleteProgram(mProgramHandle); mProgramHandle = -1; } -
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