Android OpenGL ES 2.0 (七) FramebufferObject(FBO) 转载别人好的文章

该文件直接复制粘贴的源网站为http://www.cnblogs.com/jayceli/archive/2013/04/08/3008472.html，希望博主不要生气，好东西就忍不住要收藏了
Android平台上简单的FramebufferObject示例。
FramebufferObject的概念就不说了，参考OpenGL ES 2.0 Programming Guide的第10章。
下面是render framebuffer到texture的例子。
代码的主要流程是:
创建framebuffer，绑定framebuffer，render framebuffer到texture，切换回system提供的framebuffer，利用之前产生的texture.
方便起见，两个render流程用的同样的shader.
【Android OpenGL ES 2.0 (七) FramebufferObject(FBO)】下面是renderer的代码，Test7Renderer.java

package com.android.jayce.test; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import java.nio.IntBuffer; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; import android.content.Context; import android.opengl.GLES20; import android.opengl.GLSurfaceView; import android.opengl.Matrix; import android.os.SystemClock; import com.android.jayce.test.R; /** * This class implements our custom renderer. Note that the GL10 parameter passed in is unused for OpenGL ES 2.0 * renderers -- the static class GLES20 is used instead. */ public class Test7Renderer implements GLSurfaceView.Renderer { /** Used for debug logs. */ private static final String TAG = "Test7Renderer"; private final Context mActivityContext; /** * Store the model matrix. This matrix is used to move models from object space (where each model can be thought * of being located at the center of the universe) to world space. */ private float[] mModelMatrix = new float[16]; /** * Store the view matrix. This can be thought of as our camera. This matrix transforms world space to eye space; * it positions things relative to our eye. */ private float[] mViewMatrix = new float[16]; /** Store the projection matrix. This is used to project the scene onto a 2D viewport. */ private float[] mProjectionMatrix = new float[16]; /** Allocate storage for the final combined matrix. This will be passed into the shader program. */ private float[] mMVPMatrix = new float[16]; /** Store our model data in a float buffer. */ private final FloatBuffer mCubePositions; private final FloatBuffer mCubeColors; private final FloatBuffer mCubeTextureCoordinates; /** This will be used to pass in the transformation matrix. */ private int mMVPMatrixHandle; /** This will be used to pass in the modelview matrix. */ private int mMVMatrixHandle; /** This will be used to pass in the texture. */ private int mTextureUniformHandle; /** This will be used to pass in model position information. */ private int mPositionHandle; /** This will be used to pass in model color information. */ private int mColorHandle; /** This will be used to pass in model texture coordinate information. */ private int mTextureCoordinateHandle; /** How many bytes per float. */ private final int mBytesPerFloat = 4; /** Size of the position data in elements. */ private final int mPositionDataSize = 3; /** Size of the color data in elements. */ private final int mColorDataSize = 4; /** Size of the texture coordinate data in elements. */ private final int mTextureCoordinateDataSize = 2; /** This is a handle to our cube shading program. */ private int mProgramHandle; /** This is a handle to our texture data. */ private int mTextureDataHandle; /** * Initialize the model data. */ public Test7Renderer(final Context activityContext) { mActivityContext = activityContext; // Define points for a cube.// X, Y, Z final float[] cubePositionData = https://www.it610.com/article/{ // In OpenGL counter-clockwise winding is default. This means that when we look at a triangle, // if the points are counter-clockwise we are looking at the"front". If not we are looking at // the back. OpenGL has an optimization where all back-facing triangles are culled, since they // usually represent the backside of an object and aren't visible anyways.// Front face -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f,// Right face 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f,// Back face 1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f,// Left face -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f,// Top face -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f,// Bottom face 1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, -1.0f, }; // R, G, B, A final float[] cubeColorData = https://www.it610.com/article/{ // Front face (red) 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f,// Right face (green) 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f,// Back face (blue) 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f,// Left face (yellow) 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f,// Top face (cyan) 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f,// Bottom face (magenta) 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 1.0f }; // S, T (or X, Y) // Texture coordinate data. // Because images have a Y axis pointing downward (values increase as you move down the image) while // OpenGL has a Y axis pointing upward, we adjust for that here by flipping the Y axis. // What's more is that the texture coordinates are the same for every face. final float[] cubeTextureCoordinateData = https://www.it610.com/article/{ // Front face 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,// Right face 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,// Back face 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,// Left face 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,// Top face 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f,// Bottom face 0.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f, 1.0f, 0.0f }; // Initialize the buffers. mCubePositions = ByteBuffer.allocateDirect(cubePositionData.length * mBytesPerFloat) .order(ByteOrder.nativeOrder()).asFloatBuffer(); mCubePositions.put(cubePositionData).position(0); mCubeColors = ByteBuffer.allocateDirect(cubeColorData.length * mBytesPerFloat) .order(ByteOrder.nativeOrder()).asFloatBuffer(); mCubeColors.put(cubeColorData).position(0); mCubeTextureCoordinates = ByteBuffer.allocateDirect(cubeTextureCoordinateData.length * mBytesPerFloat) .order(ByteOrder.nativeOrder()).asFloatBuffer(); mCubeTextureCoordinates.put(cubeTextureCoordinateData).position(0); }protected String getVertexShader(int shader) { return ToolsUtil.readTextFileFromRawResource(mActivityContext, shader); }protected String getFragmentShader(int shader) { return ToolsUtil.readTextFileFromRawResource(mActivityContext, shader); }@Override public void onSurfaceCreated(GL10 glUnused, EGLConfig config) { // Set the background clear color to black. GLES20.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Use culling to remove back faces. GLES20.glEnable(GLES20.GL_CULL_FACE); // Enable depth testing GLES20.glEnable(GLES20.GL_DEPTH_TEST); // The below glEnable() call is a holdover from OpenGL ES 1, and is not needed in OpenGL ES 2. // Enable texture mapping GLES20.glEnable(GLES20.GL_TEXTURE_2D); // Position the eye in front of the origin. final float eyeX = 0.0f; final float eyeY = 0.0f; final float eyeZ = -0.5f; // We are looking toward the distance final float lookX = 0.0f; final float lookY = 0.0f; final float lookZ = -5.0f; // Set our up vector. This is where our head would be pointing were we holding the camera. final float upX = 0.0f; final float upY = 1.0f; final float upZ = 0.0f; // Set the view matrix. This matrix can be said to represent the camera position. // NOTE: In OpenGL 1, a ModelView matrix is used, which is a combination of a model and // view matrix. In OpenGL 2, we can keep track of these matrices separately if we choose. Matrix.setLookAtM(mViewMatrix, 0, eyeX, eyeY, eyeZ, lookX, lookY, lookZ, upX, upY, upZ); final String vertexShader = getVertexShader(R.raw.per_pixel_vertex_shader); final String fragmentShader = getFragmentShader(R.raw.per_pixel_fragment_shader); final int vertexShaderHandle = ToolsUtil.compileShader(GLES20.GL_VERTEX_SHADER, vertexShader); final int fragmentShaderHandle = ToolsUtil.compileShader(GLES20.GL_FRAGMENT_SHADER, fragmentShader); mProgramHandle = ToolsUtil.createAndLinkProgram(vertexShaderHandle, fragmentShaderHandle, new String[] {"a_Position", "a_Color", "a_TexCoordinate"}); // Load the texture mTextureDataHandle = ToolsUtil.loadTexture(mActivityContext, R.drawable.aaa); }@Override public void onSurfaceChanged(GL10 glUnused, int width, int height) { // Set the OpenGL viewport to the same size as the surface. GLES20.glViewport(0, 0, width, height); // Create a new perspective projection matrix. The height will stay the same // while the width will vary as per aspect ratio. final float ratio = (float) width / height; final float left = -ratio; final float right = ratio; final float bottom = -1.0f; final float top = 1.0f; final float near = 1.0f; final float far = 10.0f; Matrix.frustumM(mProjectionMatrix, 0, left, right, bottom, top, near, far); }@Override public void onDrawFrame(GL10 glUnused) { IntBuffer framebuffer = IntBuffer.allocate(1); IntBuffer depthRenderbuffer = IntBuffer.allocate(1); IntBuffer texture = IntBuffer.allocate(1); int texWidth = 480, texHeight = 480; IntBuffer maxRenderbufferSize = IntBuffer.allocate(1); GLES20.glGetIntegerv(GLES20.GL_MAX_RENDERBUFFER_SIZE, maxRenderbufferSize); // check if GL_MAX_RENDERBUFFER_SIZE is >= texWidth and texHeight if((maxRenderbufferSize.get(0) <= texWidth) || (maxRenderbufferSize.get(0) <= texHeight)) { // cannot use framebuffer objects as we need to create // a depth buffer as a renderbuffer object // return with appropriate error } // generate the framebuffer, renderbuffer, and texture object names GLES20.glGenFramebuffers(1, framebuffer); GLES20.glGenRenderbuffers(1, depthRenderbuffer); GLES20.glGenTextures(1, texture); // bind texture and load the texture mip-level 0 // texels are RGB565 // no texels need to be specified as we are going to draw into // the texture GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture.get(0)); GLES20.glTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGB, texWidth, texHeight, 0, GLES20.GL_RGB, GLES20.GL_UNSIGNED_SHORT_5_6_5, null); 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); 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); // bind renderbuffer and create a 16-bit depth buffer // width and height of renderbuffer = width and height of // the texture GLES20.glBindRenderbuffer(GLES20.GL_RENDERBUFFER, depthRenderbuffer.get(0)); GLES20.glRenderbufferStorage(GLES20.GL_RENDERBUFFER, GLES20.GL_DEPTH_COMPONENT16, texWidth, texHeight); // bind the framebuffer GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, framebuffer.get(0)); // specify texture as color attachment GLES20.glFramebufferTexture2D(GLES20.GL_FRAMEBUFFER, GLES20.GL_COLOR_ATTACHMENT0, GLES20.GL_TEXTURE_2D, texture.get(0), 0); // specify depth_renderbufer as depth attachment GLES20.glFramebufferRenderbuffer(GLES20.GL_FRAMEBUFFER, GLES20.GL_DEPTH_ATTACHMENT, GLES20.GL_RENDERBUFFER, depthRenderbuffer.get(0)); // check for framebuffer complete int status = GLES20.glCheckFramebufferStatus(GLES20.GL_FRAMEBUFFER); if(status == GLES20.GL_FRAMEBUFFER_COMPLETE) { // render to texture using FBO GLES20.glClearColor(1.0f, 1.0f, 1.0f, 1.0f); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); // Do a complete rotation every 10 seconds. long time = SystemClock.uptimeMillis() % 10000L; float angleInDegrees = (360.0f / 10000.0f) * (2 * (int) time); GLES20.glUseProgram(mProgramHandle); // Set program handles for cube drawing. mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_MVPMatrix"); mMVMatrixHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_MVMatrix"); mTextureUniformHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_Texture"); mPositionHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_Position"); mColorHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_Color"); mTextureCoordinateHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_TexCoordinate"); // Set the active texture unit to texture unit 0. GLES20.glActiveTexture(GLES20.GL_TEXTURE0); // Bind the texture to this unit. GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureDataHandle); // Tell the texture uniform sampler to use this texture in the shader by binding to texture unit 0. GLES20.glUniform1i(mTextureUniformHandle, 0); Matrix.setIdentityM(mModelMatrix, 0); Matrix.translateM(mModelMatrix, 0, 0.0f, -1.0f, -5.0f); Matrix.rotateM(mModelMatrix, 0, angleInDegrees, 1.0f, 1.0f, 0.0f); drawCube(); // render to window system provided framebuffer GLES20.glBindFramebuffer(GLES20.GL_FRAMEBUFFER, 0); GLES20.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT | GLES20.GL_DEPTH_BUFFER_BIT); // Do a complete rotation every 10 seconds. time = SystemClock.uptimeMillis() % 10000L; angleInDegrees = (360.0f / 10000.0f) * ((int) time); GLES20.glUseProgram(mProgramHandle); // Set program handles for cube drawing. mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_MVPMatrix"); mMVMatrixHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_MVMatrix"); mTextureUniformHandle = GLES20.glGetUniformLocation(mProgramHandle, "u_Texture"); mPositionHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_Position"); mColorHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_Color"); mTextureCoordinateHandle = GLES20.glGetAttribLocation(mProgramHandle, "a_TexCoordinate"); // Set the active texture unit to texture unit 0. GLES20.glActiveTexture(GLES20.GL_TEXTURE0); // Bind the texture to this unit. GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texture.get(0)/*mTextureDataHandle*/); // Tell the texture uniform sampler to use this texture in the shader by binding to texture unit 0. GLES20.glUniform1i(mTextureUniformHandle, 0); Matrix.setIdentityM(mModelMatrix, 0); Matrix.translateM(mModelMatrix, 0, 0.0f, 0.0f, -5.0f); Matrix.rotateM(mModelMatrix, 0, angleInDegrees, 1.0f, 1.0f, 0.0f); drawCube(); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, 0); }// cleanup GLES20.glDeleteRenderbuffers(1, depthRenderbuffer); GLES20.glDeleteFramebuffers(1, framebuffer); GLES20.glDeleteTextures(1, texture); }/** * Draws a cube. */ private void drawCube() { // Pass in the position information mCubePositions.position(0); GLES20.glVertexAttribPointer(mPositionHandle, mPositionDataSize, GLES20.GL_FLOAT, false, 0, mCubePositions); GLES20.glEnableVertexAttribArray(mPositionHandle); // Pass in the color information mCubeColors.position(0); GLES20.glVertexAttribPointer(mColorHandle, mColorDataSize, GLES20.GL_FLOAT, false, 0, mCubeColors); GLES20.glEnableVertexAttribArray(mColorHandle); // Pass in the texture coordinate information mCubeTextureCoordinates.position(0); GLES20.glVertexAttribPointer(mTextureCoordinateHandle, mTextureCoordinateDataSize, GLES20.GL_FLOAT, false, 0, mCubeTextureCoordinates); GLES20.glEnableVertexAttribArray(mTextureCoordinateHandle); // This multiplies the view matrix by the model matrix, and stores the result in the MVP matrix // (which currently contains model * view). Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0); // Pass in the modelview matrix. GLES20.glUniformMatrix4fv(mMVMatrixHandle, 1, false, mMVPMatrix, 0); // This multiplies the modelview matrix by the projection matrix, and stores the result in the MVP matrix // (which now contains model * view * projection). Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0); // Pass in the combined matrix. GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0); // Draw the cube. GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 36); } }

还有一个辅助类,ToolsUtil.java：

package com.android.jayce.test; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.opengl.GLES20; import android.opengl.GLUtils; import android.util.Log; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; public class ToolsUtil { public static int loadTexture(final Context context, final int resourceId) { final int[] textureHandle = new int[1]; GLES20.glGenTextures(1, textureHandle, 0); if(textureHandle[0] != 0) { final BitmapFactory.Options options = new BitmapFactory.Options(); options.inScaled = false; final Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), resourceId, options); GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, textureHandle[0]); GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_NEAREST); GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_NEAREST); GLUtils.texImage2D(GLES20.GL_TEXTURE_2D, 0, bitmap, 0); bitmap.recycle(); }if(textureHandle[0] == 0) { throw new RuntimeException("failed to load texture"); }return textureHandle[0]; }/** * Helper function to compile a shader. * * @param shaderType The shader type. * @param shaderSource The shader source code. * @return An OpenGL handle to the shader. */ public static int compileShader(final int shaderType, final String shaderSource) { int shaderHandle = GLES20.glCreateShader(shaderType); if (shaderHandle != 0) { // Pass in the shader source. GLES20.glShaderSource(shaderHandle, shaderSource); // Compile the shader. GLES20.glCompileShader(shaderHandle); // Get the compilation status. final int[] compileStatus = new int[1]; GLES20.glGetShaderiv(shaderHandle, GLES20.GL_COMPILE_STATUS, compileStatus, 0); // If the compilation failed, delete the shader. if (compileStatus[0] == 0) { GLES20.glDeleteShader(shaderHandle); shaderHandle = 0; } }if (shaderHandle == 0) { throw new RuntimeException("Error creating shader."); }return shaderHandle; }/** * Helper function to compile and link a program. * * @param vertexShaderHandle An OpenGL handle to an already-compiled vertex shader. * @param fragmentShaderHandle An OpenGL handle to an already-compiled fragment shader. * @param attributes Attributes that need to be bound to the program. * @return An OpenGL handle to the program. */ public static int createAndLinkProgram(final int vertexShaderHandle, final int fragmentShaderHandle, final String[] attributes) { int programHandle = GLES20.glCreateProgram(); if (programHandle != 0) { // Bind the vertex shader to the program. GLES20.glAttachShader(programHandle, vertexShaderHandle); // Bind the fragment shader to the program. GLES20.glAttachShader(programHandle, fragmentShaderHandle); // Bind attributes if (attributes != null) { final int size = attributes.length; for (int i = 0; i < size; i++) { GLES20.glBindAttribLocation(programHandle, i, attributes[i]); } }// Link the two shaders together into a program. GLES20.glLinkProgram(programHandle); // Get the link status. final int[] linkStatus = new int[1]; GLES20.glGetProgramiv(programHandle, GLES20.GL_LINK_STATUS, linkStatus, 0); // If the link failed, delete the program. if (linkStatus[0] == 0) { GLES20.glDeleteProgram(programHandle); programHandle = 0; } }if (programHandle == 0) { throw new RuntimeException("Error creating program."); }return programHandle; }public static String readTextFileFromRawResource(final Context context, final int resourceId) { final InputStream inputStream = context.getResources().openRawResource( resourceId); final InputStreamReader inputStreamReader = new InputStreamReader( inputStream); final BufferedReader bufferedReader = new BufferedReader( inputStreamReader); String nextLine; final StringBuilder body = new StringBuilder(); try { while ((nextLine = bufferedReader.readLine()) != null) { body.append(nextLine); body.append('\n'); } } catch (IOException e) { return null; }return body.toString(); } }

使用的shader, per_pixel_vertex_shader.glsl:

uniform mat4 u_MVPMatrix; // A constant representing the combined model/view/projection matrix. uniform mat4 u_MVMatrix; // A constant representing the combined model/view matrix.attribute vec4 a_Position; // Per-vertex position information we will pass in. attribute vec4 a_Color; // Per-vertex color information we will pass in. attribute vec2 a_TexCoordinate; // Per-vertex texture coordinate information we will pass in.varying vec3 v_Position; // This will be passed into the fragment shader. varying vec4 v_Color; // This will be passed into the fragment shader. varying vec2 v_TexCoordinate; // This will be passed into the fragment shader.// The entry point for our vertex shader. void main() { // Transform the vertex into eye space. v_Position = vec3(u_MVMatrix * a_Position); // Pass through the color. v_Color = a_Color; // Pass through the texture coordinate. v_TexCoordinate = a_TexCoordinate; // gl_Position is a special variable used to store the final position. // Multiply the vertex by the matrix to get the final point in normalized screen coordinates. gl_Position = u_MVPMatrix * a_Position; }

使用的shader, per_pixel_fragment_shader.glsl:

precision mediump float; // Set the default precision to medium. We don't need as high of a // precision in the fragment shader. uniform sampler2D u_Texture; // The input texture.varying vec3 v_Position; // Interpolated position for this fragment. varying vec4 v_Color; // This is the color from the vertex shader interpolated across the varying vec2 v_TexCoordinate; // Interpolated texture coordinate per fragment.// The entry point for our fragment shader. void main() { // Multiply the color by the diffuse illumination level and texture value to get final output color. gl_FragColor = (v_Color * texture2D(u_Texture, v_TexCoordinate)); }

好了，就这么多了，可以看到旋转立方体每一面的texture都是用的自己创建的framebuffer render的texture，每面都有一个旋转的立方体。
好了，就这么多了，可以看到旋转立方体每一面的texture都是用的自己创建的framebuffer render的texture，每面都有一个旋转的立方体。
看看效果图吧：