opengl/tests/gl2_copyTexImage/gl2_copyTexImage.cpp - platform/frameworks/native - Git at Google

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <stdlib.h>
 #include <stdio.h>
 #include <time.h>
 #include <sched.h>
 #include <sys/resource.h>

 #include <EGL/egl.h>
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>

 #include <utils/Timers.h>

 #include <ui/FramebufferNativeWindow.h>
 #include "EGLUtils.h"

 using namespace android;

 static void printGLString(const char *name, GLenum s) {
     // fprintf(stderr, "printGLString %s, %d\n", name, s);
     const char *v = (const char *) glGetString(s);
     // int error = glGetError();
     // fprintf(stderr, "glGetError() = %d, result of glGetString = %x\n", error,
     //        (unsigned int) v);
     // if ((v < (const char*) 0) || (v > (const char*) 0x10000))
     //    fprintf(stderr, "GL %s = %s\n", name, v);
     // else
     //    fprintf(stderr, "GL %s = (null) 0x%08x\n", name, (unsigned int) v);
     fprintf(stderr, "GL %s = %s\n", name, v);
 }

 static void checkEglError(const char* op, EGLBoolean returnVal = EGL_TRUE) {
     if (returnVal != EGL_TRUE) {
         fprintf(stderr, "%s() returned %d\n", op, returnVal);
     }

     for (EGLint error = eglGetError(); error != EGL_SUCCESS; error
             = eglGetError()) {
         fprintf(stderr, "after %s() eglError %s (0x%x)\n", op, EGLUtils::strerror(error),
                 error);
     }
 }

 static void checkGlError(const char* op) {
     for (GLint error = glGetError(); error; error
             = glGetError()) {
         fprintf(stderr, "after %s() glError (0x%x)\n", op, error);
     }
 }

 static const char gVertexShader[] = "attribute vec4 vPosition;\n"
     "void main() {\n"
     "  gl_Position = vPosition;\n"
     "}\n";

 static const char gFragmentShader[] = "precision mediump float;\n"
     "void main() {\n"
     "  gl_FragColor = vec4(0.0, 1.0, 0.0, 0.5);\n"
     "}\n";

 GLuint loadShader(GLenum shaderType, const char* pSource) {
     GLuint shader = glCreateShader(shaderType);
     if (shader) {
         glShaderSource(shader, 1, &pSource, NULL);
         glCompileShader(shader);
         GLint compiled = 0;
         glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
         if (!compiled) {
             GLint infoLen = 0;
             glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
             if (infoLen) {
                 char* buf = (char*) malloc(infoLen);
                 if (buf) {
                     glGetShaderInfoLog(shader, infoLen, NULL, buf);
                     fprintf(stderr, "Could not compile shader %d:\n%s\n",
                             shaderType, buf);
                     free(buf);
                 }
                 glDeleteShader(shader);
                 shader = 0;
             }
         }
     }
     return shader;
 }

 GLuint createProgram(const char* pVertexSource, const char* pFragmentSource) {
     GLuint vertexShader = loadShader(GL_VERTEX_SHADER, pVertexSource);
     if (!vertexShader) {
         return 0;
     }

     GLuint pixelShader = loadShader(GL_FRAGMENT_SHADER, pFragmentSource);
     if (!pixelShader) {
         return 0;
     }

     GLuint program = glCreateProgram();
     if (program) {
         glAttachShader(program, vertexShader);
         checkGlError("glAttachShader");
         glAttachShader(program, pixelShader);
         checkGlError("glAttachShader");
         glLinkProgram(program);
         GLint linkStatus = GL_FALSE;
         glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
         if (linkStatus != GL_TRUE) {
             GLint bufLength = 0;
             glGetProgramiv(program, GL_INFO_LOG_LENGTH, &bufLength);
             if (bufLength) {
                 char* buf = (char*) malloc(bufLength);
                 if (buf) {
                     glGetProgramInfoLog(program, bufLength, NULL, buf);
                     fprintf(stderr, "Could not link program:\n%s\n", buf);
                     free(buf);
                 }
             }
             glDeleteProgram(program);
             program = 0;
         }
     }
     return program;
 }

 GLuint gProgram;
 GLuint gTextureProgram;
 GLuint gvPositionHandle;
 GLuint gvTexturePositionHandle;
 GLuint gvTextureTexCoordsHandle;
 GLuint gvTextureSamplerHandle;
 GLuint gFbo;
 GLuint gTexture;
 GLuint gBufferTexture;

 static const char gSimpleVS[] =
     "attribute vec4 position;\n"
     "attribute vec2 texCoords;\n"
     "varying vec2 outTexCoords;\n"
     "\nvoid main(void) {\n"
     "    outTexCoords = texCoords;\n"
     "    gl_Position = position;\n"
     "}\n\n";
 static const char gSimpleFS[] =
     "precision mediump float;\n\n"
     "varying vec2 outTexCoords;\n"
     "uniform sampler2D texture;\n"
     "\nvoid main(void) {\n"
     "    gl_FragColor = texture2D(texture, outTexCoords);\n"
     "}\n\n";

 bool setupGraphics(int w, int h) {
     gProgram = createProgram(gVertexShader, gFragmentShader);
     if (!gProgram) {
         return false;
     }
     gvPositionHandle = glGetAttribLocation(gProgram, "vPosition");
     checkGlError("glGetAttribLocation");
     fprintf(stderr, "glGetAttribLocation(\"vPosition\") = %d\n", gvPositionHandle);

     gTextureProgram = createProgram(gSimpleVS, gSimpleFS);
     if (!gTextureProgram) {
         return false;
     }
     gvTexturePositionHandle = glGetAttribLocation(gTextureProgram, "position");
     checkGlError("glGetAttribLocation");
     gvTextureTexCoordsHandle = glGetAttribLocation(gTextureProgram, "texCoords");
     checkGlError("glGetAttribLocation");
     gvTextureSamplerHandle = glGetUniformLocation(gTextureProgram, "texture");
     checkGlError("glGetAttribLocation");

     glActiveTexture(GL_TEXTURE0);

     glGenTextures(1, &gTexture);
     glBindTexture(GL_TEXTURE_2D, gTexture);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

     glGenTextures(1, &gBufferTexture);
     glBindTexture(GL_TEXTURE_2D, gBufferTexture);
     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

     glGenFramebuffers(1, &gFbo);
     glBindFramebuffer(GL_FRAMEBUFFER, gFbo);
     glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gTexture, 0);

     glBindFramebuffer(GL_FRAMEBUFFER, 0);

     glViewport(0, 0, w, h);
     checkGlError("glViewport");
     return true;
 }

 const GLfloat gTriangleVertices[] = { 0.0f, 0.5f, -0.5f, -0.5f,
         0.5f, -0.5f };

 const GLint FLOAT_SIZE_BYTES = 4;
 const GLint TRIANGLE_VERTICES_DATA_STRIDE_BYTES = 5 * FLOAT_SIZE_BYTES;
 const GLfloat gTriangleVerticesData[] = {
     // X, Y, Z, U, V
     -1.0f, -1.0f, 0, 0.f, 0.f,
     1.0f, -1.0f, 0, 1.f, 0.f,
     -1.0f,  1.0f, 0, 0.f, 1.f,
     1.0f,   1.0f, 0, 1.f, 1.f,
 };

 void renderFrame(GLint w, GLint h) {
     glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
     checkGlError("glClearColor");
     glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
     checkGlError("glClear");

     // Bind FBO and draw into it
     glBindFramebuffer(GL_FRAMEBUFFER, gFbo);
     checkGlError("glBindFramebuffer");

     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
     checkGlError("glClearColor");
     glClear(GL_COLOR_BUFFER_BIT);
     checkGlError("glClear");

     glUseProgram(gProgram);
     checkGlError("glUseProgram");

     glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
     checkGlError("glVertexAttribPointer");
     glEnableVertexAttribArray(gvPositionHandle);
     checkGlError("glEnableVertexAttribArray");
     glDrawArrays(GL_TRIANGLES, 0, 3);
     checkGlError("glDrawArrays");

     // Copy content of FBO into a texture
     glBindTexture(GL_TEXTURE_2D, gBufferTexture);
     glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, w / 2, h / 2);
     checkGlError("glCopyTexSubImage2D");

     // Back to the display
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
     checkGlError("glBindFramebuffer");

     // Draw copied content on the screen
     glUseProgram(gTextureProgram);
     checkGlError("glUseProgram");

     glEnable(GL_BLEND);
     glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

     glVertexAttribPointer(gvTexturePositionHandle, 3, GL_FLOAT, GL_FALSE,
             TRIANGLE_VERTICES_DATA_STRIDE_BYTES, gTriangleVerticesData);
     checkGlError("glVertexAttribPointer");
     glVertexAttribPointer(gvTextureTexCoordsHandle, 2, GL_FLOAT, GL_FALSE,
             TRIANGLE_VERTICES_DATA_STRIDE_BYTES, &gTriangleVerticesData[3]);
     checkGlError("glVertexAttribPointer");
     glEnableVertexAttribArray(gvTexturePositionHandle);
     glEnableVertexAttribArray(gvTextureTexCoordsHandle);
     checkGlError("glEnableVertexAttribArray");
     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
     checkGlError("glDrawArrays");
 }

 void printEGLConfiguration(EGLDisplay dpy, EGLConfig config) {

 #define X(VAL) {VAL, #VAL}
     struct {EGLint attribute; const char* name;} names[] = {
     X(EGL_BUFFER_SIZE),
     X(EGL_ALPHA_SIZE),
     X(EGL_BLUE_SIZE),
     X(EGL_GREEN_SIZE),
     X(EGL_RED_SIZE),
     X(EGL_DEPTH_SIZE),
     X(EGL_STENCIL_SIZE),
     X(EGL_CONFIG_CAVEAT),
     X(EGL_CONFIG_ID),
     X(EGL_LEVEL),
     X(EGL_MAX_PBUFFER_HEIGHT),
     X(EGL_MAX_PBUFFER_PIXELS),
     X(EGL_MAX_PBUFFER_WIDTH),
     X(EGL_NATIVE_RENDERABLE),
     X(EGL_NATIVE_VISUAL_ID),
     X(EGL_NATIVE_VISUAL_TYPE),
     X(EGL_SAMPLES),
     X(EGL_SAMPLE_BUFFERS),
     X(EGL_SURFACE_TYPE),
     X(EGL_TRANSPARENT_TYPE),
     X(EGL_TRANSPARENT_RED_VALUE),
     X(EGL_TRANSPARENT_GREEN_VALUE),
     X(EGL_TRANSPARENT_BLUE_VALUE),
     X(EGL_BIND_TO_TEXTURE_RGB),
     X(EGL_BIND_TO_TEXTURE_RGBA),
     X(EGL_MIN_SWAP_INTERVAL),
     X(EGL_MAX_SWAP_INTERVAL),
     X(EGL_LUMINANCE_SIZE),
     X(EGL_ALPHA_MASK_SIZE),
     X(EGL_COLOR_BUFFER_TYPE),
     X(EGL_RENDERABLE_TYPE),
     X(EGL_CONFORMANT),
    };
 #undef X

     for (size_t j = 0; j < sizeof(names) / sizeof(names[0]); j++) {
         EGLint value = -1;
         EGLint returnVal = eglGetConfigAttrib(dpy, config, names[j].attribute, &value);
         EGLint error = eglGetError();
         if (returnVal && error == EGL_SUCCESS) {
             printf(" %s: ", names[j].name);
             printf("%d (0x%x)", value, value);
         }
     }
     printf("\n");
 }

 int printEGLConfigurations(EGLDisplay dpy) {
     EGLint numConfig = 0;
     EGLint returnVal = eglGetConfigs(dpy, NULL, 0, &numConfig);
     checkEglError("eglGetConfigs", returnVal);
     if (!returnVal) {
         return false;
     }

     printf("Number of EGL configuration: %d\n", numConfig);

     EGLConfig* configs = (EGLConfig*) malloc(sizeof(EGLConfig) * numConfig);
     if (! configs) {
         printf("Could not allocate configs.\n");
         return false;
     }

     returnVal = eglGetConfigs(dpy, configs, numConfig, &numConfig);
     checkEglError("eglGetConfigs", returnVal);
     if (!returnVal) {
         free(configs);
         return false;
     }

     for(int i = 0; i < numConfig; i++) {
         printf("Configuration %d\n", i);
         printEGLConfiguration(dpy, configs[i]);
     }

     free(configs);
     return true;
 }

 int main(int argc, char** argv) {
     EGLBoolean returnValue;
     EGLConfig myConfig = {0};

     EGLint context_attribs[] = { EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE };
     EGLint s_configAttribs[] = {
             EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
             EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
             EGL_RED_SIZE, 8,
             EGL_GREEN_SIZE, 8,
             EGL_BLUE_SIZE, 8,
             EGL_ALPHA_SIZE, 8,
             EGL_NONE };
     EGLint majorVersion;
     EGLint minorVersion;
     EGLContext context;
     EGLSurface surface;
     EGLint w, h;

     EGLDisplay dpy;

     checkEglError("<init>");
     dpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
     checkEglError("eglGetDisplay");
     if (dpy == EGL_NO_DISPLAY) {
         printf("eglGetDisplay returned EGL_NO_DISPLAY.\n");
         return 0;
     }

     returnValue = eglInitialize(dpy, &majorVersion, &minorVersion);
     checkEglError("eglInitialize", returnValue);
     fprintf(stderr, "EGL version %d.%d\n", majorVersion, minorVersion);
     if (returnValue != EGL_TRUE) {
         printf("eglInitialize failed\n");
         return 0;
     }

     if (!printEGLConfigurations(dpy)) {
         printf("printEGLConfigurations failed\n");
         return 0;
     }

     checkEglError("printEGLConfigurations");

     EGLNativeWindowType window = android_createDisplaySurface();
     EGLint numConfigs = -1, n = 0;
     eglChooseConfig(dpy, s_configAttribs, 0, 0, &numConfigs);
     if (numConfigs) {
         EGLConfig* const configs = new EGLConfig[numConfigs];
         eglChooseConfig(dpy, s_configAttribs, configs, numConfigs, &n);
         myConfig = configs[0];
         delete[] configs;
     }

     checkEglError("EGLUtils::selectConfigForNativeWindow");

     printf("Chose this configuration:\n");
     printEGLConfiguration(dpy, myConfig);

     surface = eglCreateWindowSurface(dpy, myConfig, window, NULL);
     checkEglError("eglCreateWindowSurface");
     if (surface == EGL_NO_SURFACE) {
         printf("gelCreateWindowSurface failed.\n");
         return 0;
     }

     context = eglCreateContext(dpy, myConfig, EGL_NO_CONTEXT, context_attribs);
     checkEglError("eglCreateContext");
     if (context == EGL_NO_CONTEXT) {
         printf("eglCreateContext failed\n");
         return 0;
     }
     returnValue = eglMakeCurrent(dpy, surface, surface, context);
     checkEglError("eglMakeCurrent", returnValue);
     if (returnValue != EGL_TRUE) {
         return 0;
     }
     eglQuerySurface(dpy, surface, EGL_WIDTH, &w);
     checkEglError("eglQuerySurface");
     eglQuerySurface(dpy, surface, EGL_HEIGHT, &h);
     checkEglError("eglQuerySurface");
     GLint dim = w < h ? w : h;

     fprintf(stderr, "Window dimensions: %d x %d\n", w, h);

     printGLString("Version", GL_VERSION);
     printGLString("Vendor", GL_VENDOR);
     printGLString("Renderer", GL_RENDERER);
     printGLString("Extensions", GL_EXTENSIONS);

     if(!setupGraphics(w, h)) {
         fprintf(stderr, "Could not set up graphics.\n");
         return 0;
     }

     for (;;) {
         renderFrame(w, h);
         eglSwapBuffers(dpy, surface);
         checkEglError("eglSwapBuffers");
     }

     return 0;
 }
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <stdlib.h>
	#include <stdio.h>
	#include <time.h>
	#include <sched.h>
	#include <sys/resource.h>

	#include <EGL/egl.h>
	#include <GLES2/gl2.h>
	#include <GLES2/gl2ext.h>

	#include <utils/Timers.h>

	#include <ui/FramebufferNativeWindow.h>
	#include "EGLUtils.h"

	using namespace android;

	static void printGLString(const char *name, GLenum s) {
	// fprintf(stderr, "printGLString %s, %d\n", name, s);
	const char v = (const char ) glGetString(s);
	// int error = glGetError();
	// fprintf(stderr, "glGetError() = %d, result of glGetString = %x\n", error,
	// (unsigned int) v);
	// if ((v < (const char) 0) \|\| (v > (const char) 0x10000))
	// fprintf(stderr, "GL %s = %s\n", name, v);
	// else
	// fprintf(stderr, "GL %s = (null) 0x%08x\n", name, (unsigned int) v);
	fprintf(stderr, "GL %s = %s\n", name, v);
	}

	static void checkEglError(const char* op, EGLBoolean returnVal = EGL_TRUE) {
	if (returnVal != EGL_TRUE) {
	fprintf(stderr, "%s() returned %d\n", op, returnVal);
	}

	for (EGLint error = eglGetError(); error != EGL_SUCCESS; error
	= eglGetError()) {
	fprintf(stderr, "after %s() eglError %s (0x%x)\n", op, EGLUtils::strerror(error),
	error);
	}
	}

	static void checkGlError(const char* op) {
	for (GLint error = glGetError(); error; error
	= glGetError()) {
	fprintf(stderr, "after %s() glError (0x%x)\n", op, error);
	}
	}

	static const char gVertexShader[] = "attribute vec4 vPosition;\n"
	"void main() {\n"
	" gl_Position = vPosition;\n"
	"}\n";

	static const char gFragmentShader[] = "precision mediump float;\n"
	"void main() {\n"
	" gl_FragColor = vec4(0.0, 1.0, 0.0, 0.5);\n"
	"}\n";

	GLuint loadShader(GLenum shaderType, const char* pSource) {
	GLuint shader = glCreateShader(shaderType);
	if (shader) {
	glShaderSource(shader, 1, &pSource, NULL);
	glCompileShader(shader);
	GLint compiled = 0;
	glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
	if (!compiled) {
	GLint infoLen = 0;
	glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
	if (infoLen) {
	char* buf = (char*) malloc(infoLen);
	if (buf) {
	glGetShaderInfoLog(shader, infoLen, NULL, buf);
	fprintf(stderr, "Could not compile shader %d:\n%s\n",
	shaderType, buf);
	free(buf);
	}
	glDeleteShader(shader);
	shader = 0;
	}
	}
	}
	return shader;
	}

	GLuint createProgram(const char* pVertexSource, const char* pFragmentSource) {
	GLuint vertexShader = loadShader(GL_VERTEX_SHADER, pVertexSource);
	if (!vertexShader) {
	return 0;
	}

	GLuint pixelShader = loadShader(GL_FRAGMENT_SHADER, pFragmentSource);
	if (!pixelShader) {
	return 0;
	}

	GLuint program = glCreateProgram();
	if (program) {
	glAttachShader(program, vertexShader);
	checkGlError("glAttachShader");
	glAttachShader(program, pixelShader);
	checkGlError("glAttachShader");
	glLinkProgram(program);
	GLint linkStatus = GL_FALSE;
	glGetProgramiv(program, GL_LINK_STATUS, &linkStatus);
	if (linkStatus != GL_TRUE) {
	GLint bufLength = 0;
	glGetProgramiv(program, GL_INFO_LOG_LENGTH, &bufLength);
	if (bufLength) {
	char* buf = (char*) malloc(bufLength);
	if (buf) {
	glGetProgramInfoLog(program, bufLength, NULL, buf);
	fprintf(stderr, "Could not link program:\n%s\n", buf);
	free(buf);
	}
	}
	glDeleteProgram(program);
	program = 0;
	}
	}
	return program;
	}

	GLuint gProgram;
	GLuint gTextureProgram;
	GLuint gvPositionHandle;
	GLuint gvTexturePositionHandle;
	GLuint gvTextureTexCoordsHandle;
	GLuint gvTextureSamplerHandle;
	GLuint gFbo;
	GLuint gTexture;
	GLuint gBufferTexture;

	static const char gSimpleVS[] =
	"attribute vec4 position;\n"
	"attribute vec2 texCoords;\n"
	"varying vec2 outTexCoords;\n"
	"\nvoid main(void) {\n"
	" outTexCoords = texCoords;\n"
	" gl_Position = position;\n"
	"}\n\n";
	static const char gSimpleFS[] =
	"precision mediump float;\n\n"
	"varying vec2 outTexCoords;\n"
	"uniform sampler2D texture;\n"
	"\nvoid main(void) {\n"
	" gl_FragColor = texture2D(texture, outTexCoords);\n"
	"}\n\n";

	bool setupGraphics(int w, int h) {
	gProgram = createProgram(gVertexShader, gFragmentShader);
	if (!gProgram) {
	return false;
	}
	gvPositionHandle = glGetAttribLocation(gProgram, "vPosition");
	checkGlError("glGetAttribLocation");
	fprintf(stderr, "glGetAttribLocation(\"vPosition\") = %d\n", gvPositionHandle);

	gTextureProgram = createProgram(gSimpleVS, gSimpleFS);
	if (!gTextureProgram) {
	return false;
	}
	gvTexturePositionHandle = glGetAttribLocation(gTextureProgram, "position");
	checkGlError("glGetAttribLocation");
	gvTextureTexCoordsHandle = glGetAttribLocation(gTextureProgram, "texCoords");
	checkGlError("glGetAttribLocation");
	gvTextureSamplerHandle = glGetUniformLocation(gTextureProgram, "texture");
	checkGlError("glGetAttribLocation");

	glActiveTexture(GL_TEXTURE0);

	glGenTextures(1, &gTexture);
	glBindTexture(GL_TEXTURE_2D, gTexture);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	glGenTextures(1, &gBufferTexture);
	glBindTexture(GL_TEXTURE_2D, gBufferTexture);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

	glGenFramebuffers(1, &gFbo);
	glBindFramebuffer(GL_FRAMEBUFFER, gFbo);
	glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, gTexture, 0);

	glBindFramebuffer(GL_FRAMEBUFFER, 0);

	glViewport(0, 0, w, h);
	checkGlError("glViewport");
	return true;
	}

	const GLfloat gTriangleVertices[] = { 0.0f, 0.5f, -0.5f, -0.5f,
	0.5f, -0.5f };

	const GLint FLOAT_SIZE_BYTES = 4;
	const GLint TRIANGLE_VERTICES_DATA_STRIDE_BYTES = 5 * FLOAT_SIZE_BYTES;
	const GLfloat gTriangleVerticesData[] = {
	// X, Y, Z, U, V
	-1.0f, -1.0f, 0, 0.f, 0.f,
	1.0f, -1.0f, 0, 1.f, 0.f,
	-1.0f, 1.0f, 0, 0.f, 1.f,
	1.0f, 1.0f, 0, 1.f, 1.f,
	};

	void renderFrame(GLint w, GLint h) {
	glClearColor(1.0f, 0.0f, 0.0f, 1.0f);
	checkGlError("glClearColor");
	glClear(GL_DEPTH_BUFFER_BIT \| GL_COLOR_BUFFER_BIT);
	checkGlError("glClear");

	// Bind FBO and draw into it
	glBindFramebuffer(GL_FRAMEBUFFER, gFbo);
	checkGlError("glBindFramebuffer");

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	checkGlError("glClearColor");
	glClear(GL_COLOR_BUFFER_BIT);
	checkGlError("glClear");

	glUseProgram(gProgram);
	checkGlError("glUseProgram");

	glVertexAttribPointer(gvPositionHandle, 2, GL_FLOAT, GL_FALSE, 0, gTriangleVertices);
	checkGlError("glVertexAttribPointer");
	glEnableVertexAttribArray(gvPositionHandle);
	checkGlError("glEnableVertexAttribArray");
	glDrawArrays(GL_TRIANGLES, 0, 3);
	checkGlError("glDrawArrays");

	// Copy content of FBO into a texture
	glBindTexture(GL_TEXTURE_2D, gBufferTexture);
	glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, w / 2, h / 2);
	checkGlError("glCopyTexSubImage2D");

	// Back to the display
	glBindFramebuffer(GL_FRAMEBUFFER, 0);
	checkGlError("glBindFramebuffer");

	// Draw copied content on the screen
	glUseProgram(gTextureProgram);
	checkGlError("glUseProgram");

	glEnable(GL_BLEND);
	glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

	glVertexAttribPointer(gvTexturePositionHandle, 3, GL_FLOAT, GL_FALSE,
	TRIANGLE_VERTICES_DATA_STRIDE_BYTES, gTriangleVerticesData);
	checkGlError("glVertexAttribPointer");
	glVertexAttribPointer(gvTextureTexCoordsHandle, 2, GL_FLOAT, GL_FALSE,
	TRIANGLE_VERTICES_DATA_STRIDE_BYTES, &gTriangleVerticesData[3]);
	checkGlError("glVertexAttribPointer");
	glEnableVertexAttribArray(gvTexturePositionHandle);
	glEnableVertexAttribArray(gvTextureTexCoordsHandle);
	checkGlError("glEnableVertexAttribArray");
	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
	checkGlError("glDrawArrays");
	}

	void printEGLConfiguration(EGLDisplay dpy, EGLConfig config) {

	#define X(VAL) {VAL, #VAL}
	struct {EGLint attribute; const char* name;} names[] = {
	X(EGL_BUFFER_SIZE),
	X(EGL_ALPHA_SIZE),
	X(EGL_BLUE_SIZE),
	X(EGL_GREEN_SIZE),
	X(EGL_RED_SIZE),
	X(EGL_DEPTH_SIZE),
	X(EGL_STENCIL_SIZE),
	X(EGL_CONFIG_CAVEAT),
	X(EGL_CONFIG_ID),
	X(EGL_LEVEL),
	X(EGL_MAX_PBUFFER_HEIGHT),
	X(EGL_MAX_PBUFFER_PIXELS),
	X(EGL_MAX_PBUFFER_WIDTH),
	X(EGL_NATIVE_RENDERABLE),
	X(EGL_NATIVE_VISUAL_ID),
	X(EGL_NATIVE_VISUAL_TYPE),
	X(EGL_SAMPLES),
	X(EGL_SAMPLE_BUFFERS),
	X(EGL_SURFACE_TYPE),
	X(EGL_TRANSPARENT_TYPE),
	X(EGL_TRANSPARENT_RED_VALUE),
	X(EGL_TRANSPARENT_GREEN_VALUE),
	X(EGL_TRANSPARENT_BLUE_VALUE),
	X(EGL_BIND_TO_TEXTURE_RGB),
	X(EGL_BIND_TO_TEXTURE_RGBA),
	X(EGL_MIN_SWAP_INTERVAL),
	X(EGL_MAX_SWAP_INTERVAL),
	X(EGL_LUMINANCE_SIZE),
	X(EGL_ALPHA_MASK_SIZE),
	X(EGL_COLOR_BUFFER_TYPE),
	X(EGL_RENDERABLE_TYPE),
	X(EGL_CONFORMANT),
	};
	#undef X

	for (size_t j = 0; j < sizeof(names) / sizeof(names[0]); j++) {
	EGLint value = -1;
	EGLint returnVal = eglGetConfigAttrib(dpy, config, names[j].attribute, &value);
	EGLint error = eglGetError();
	if (returnVal && error == EGL_SUCCESS) {
	printf(" %s: ", names[j].name);
	printf("%d (0x%x)", value, value);
	}
	}
	printf("\n");
	}

	int printEGLConfigurations(EGLDisplay dpy) {
	EGLint numConfig = 0;
	EGLint returnVal = eglGetConfigs(dpy, NULL, 0, &numConfig);
	checkEglError("eglGetConfigs", returnVal);
	if (!returnVal) {
	return false;
	}

	printf("Number of EGL configuration: %d\n", numConfig);

	EGLConfig* configs = (EGLConfig) malloc(sizeof(EGLConfig) numConfig);
	if (! configs) {
	printf("Could not allocate configs.\n");
	return false;
	}

	returnVal = eglGetConfigs(dpy, configs, numConfig, &numConfig);
	checkEglError("eglGetConfigs", returnVal);
	if (!returnVal) {
	free(configs);
	return false;
	}

	for(int i = 0; i < numConfig; i++) {
	printf("Configuration %d\n", i);
	printEGLConfiguration(dpy, configs[i]);
	}

	free(configs);
	return true;
	}

	int main(int argc, char** argv) {
	EGLBoolean returnValue;
	EGLConfig myConfig = {0};

	EGLint context_attribs[] = { EGL_CONTEXT_CLIENT_VERSION, 2, EGL_NONE };
	EGLint s_configAttribs[] = {
	EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
	EGL_RENDERABLE_TYPE, EGL_OPENGL_ES2_BIT,
	EGL_RED_SIZE, 8,
	EGL_GREEN_SIZE, 8,
	EGL_BLUE_SIZE, 8,
	EGL_ALPHA_SIZE, 8,
	EGL_NONE };
	EGLint majorVersion;
	EGLint minorVersion;
	EGLContext context;
	EGLSurface surface;
	EGLint w, h;

	EGLDisplay dpy;

	checkEglError("<init>");
	dpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
	checkEglError("eglGetDisplay");
	if (dpy == EGL_NO_DISPLAY) {
	printf("eglGetDisplay returned EGL_NO_DISPLAY.\n");
	return 0;
	}

	returnValue = eglInitialize(dpy, &majorVersion, &minorVersion);
	checkEglError("eglInitialize", returnValue);
	fprintf(stderr, "EGL version %d.%d\n", majorVersion, minorVersion);
	if (returnValue != EGL_TRUE) {
	printf("eglInitialize failed\n");
	return 0;
	}

	if (!printEGLConfigurations(dpy)) {
	printf("printEGLConfigurations failed\n");
	return 0;
	}

	checkEglError("printEGLConfigurations");

	EGLNativeWindowType window = android_createDisplaySurface();
	EGLint numConfigs = -1, n = 0;
	eglChooseConfig(dpy, s_configAttribs, 0, 0, &numConfigs);
	if (numConfigs) {
	EGLConfig* const configs = new EGLConfig[numConfigs];
	eglChooseConfig(dpy, s_configAttribs, configs, numConfigs, &n);
	myConfig = configs[0];
	delete[] configs;
	}

	checkEglError("EGLUtils::selectConfigForNativeWindow");

	printf("Chose this configuration:\n");
	printEGLConfiguration(dpy, myConfig);

	surface = eglCreateWindowSurface(dpy, myConfig, window, NULL);
	checkEglError("eglCreateWindowSurface");
	if (surface == EGL_NO_SURFACE) {
	printf("gelCreateWindowSurface failed.\n");
	return 0;
	}

	context = eglCreateContext(dpy, myConfig, EGL_NO_CONTEXT, context_attribs);
	checkEglError("eglCreateContext");
	if (context == EGL_NO_CONTEXT) {
	printf("eglCreateContext failed\n");
	return 0;
	}
	returnValue = eglMakeCurrent(dpy, surface, surface, context);
	checkEglError("eglMakeCurrent", returnValue);
	if (returnValue != EGL_TRUE) {
	return 0;
	}
	eglQuerySurface(dpy, surface, EGL_WIDTH, &w);
	checkEglError("eglQuerySurface");
	eglQuerySurface(dpy, surface, EGL_HEIGHT, &h);
	checkEglError("eglQuerySurface");
	GLint dim = w < h ? w : h;

	fprintf(stderr, "Window dimensions: %d x %d\n", w, h);

	printGLString("Version", GL_VERSION);
	printGLString("Vendor", GL_VENDOR);
	printGLString("Renderer", GL_RENDERER);
	printGLString("Extensions", GL_EXTENSIONS);

	if(!setupGraphics(w, h)) {
	fprintf(stderr, "Could not set up graphics.\n");
	return 0;
	}

	for (;;) {
	renderFrame(w, h);
	eglSwapBuffers(dpy, surface);
	checkEglError("eglSwapBuffers");
	}

	return 0;
	}