android 下使用Direct Texture

要使用Direct Texture,需要有一份android系统的源码

部分C++代码如下：

#include <stdio.h>

#include <stdlib.h>

#include <GLES2/gl2.h>

#include <GLES2/gl2ext.h>

#include <EGL/egl.h>

#include <EGL/eglext.h>

#include <android/native_window.h>

#include <ui/GraphicBuffer.h>

#include <dlfcn.h>

#include <jni.h>

#include "render_native.h"

 

int Graphics::initGL(){

 

     const char* const driver_absolute_path = "/system/lib/egl/libEGL_mali.so";

    // On Gingerbread you have to load symbols manually from Mali driver because

    // Android EGL library has a bug.

    // From  ICE CREAM SANDWICH you can freely use the eglGetProcAddress function.

    // You might be able to get away with just eglGetProcAddress (no dlopen). Tr y it,  else revert to the following code

    void* dso = dlopen(driver_absolute_path, RTLD_LAZY);

    if (dso != 0)

    {

        LOGI("dlopen: SUCCEEDED");

        _eglCreateImageKHR = (PFNEGLCREATEIMAGEKHRPROC)dlsym(dso, "eglCreateImageKHR");

        _eglDestroyImageKHR = (PFNEGLDESTROYIMAGEKHRPROC) dlsym(dso,"eglDestroyImageKHR");

    }

    else

    {

        LOGI("dlopen: FAILED! Loading functions in common way!");

        _eglCreateImageKHR = (PFNEGLCREATEIMAGEKHRPROC) eglGetProcAddress("eglCreateImageKHR");

        _eglDestroyImageKHR = (PFNEGLDESTROYIMAGEKHRPROC) eglGetProcAddress("eglDestroyImageKHR");

    }

 

    if(_eglCreateImageKHR == NULL)

    {

        LOGE("Error: Failed to find eglCreateImageKHR at %s:%in", __FILE__, __LINE__);

        exit(1);

    }

    if(_eglDestroyImageKHR == NULL)

    {

        LOGE("Error: Failed to find eglDestroyImageKHR at %s:%in", __FILE__, __LINE__);

        exit(1);

    }

        _glEGLImageTargetTexture2DOES = (PFNGLEGLIMAGETARGETTEXTURE2DOESPROC) eglGetProcAddress("glEGLImageTargetTexture2DOES");

    if(_glEGLImageTargetTexture2DOES == NULL)

    {

        LOGI("Error: Failed to find glEGLImageTargetTexture2DOES at %s:%in", __FILE__, __LINE__);

        return 0;

    }

     

    graphicBuffer = new GraphicBuffer( emu_width,emu_height,

            HAL_PIXEL_FORMAT_RGBA_8888,

            GraphicBuffer::USAGE_HW_TEXTURE |

            GraphicBuffer::USAGE_HW_2D |

            GRALLOC_USAGE_SW_READ_OFTEN |

            GRALLOC_USAGE_SW_WRITE_OFTEN);

             

    status_t err = graphicBuffer->initCheck();

    if (err != NO_ERROR)

    {

        LOGI("Error: %sn", strerror(-err));

        return 0;

    }

     

    GGLSurface t;

    //   graphicBuffer->lock(GraphicBuffer::USAGE_SW_WRITE_OFTEN, &addr);

    graphicBuffer->lock(&t, GRALLOC_USAGE_SW_WRITE_OFTEN);

           

    memset(t.data,128,t.stride*t.height);

    graphicBuffer->unlock();

     

     

    // Retrieve andorid native buffer

    android_native_buffer_t* anb =graphicBuffer->getNativeBuffer();

    // create the new EGLImageKHR

    const EGLint attrs[] =

    {

        EGL_IMAGE_PRESERVED_KHR, EGL_TRUE,

        EGL_NONE, EGL_NONE

    };

     

    mEngine.mTexture.pEGLImage = _eglCreateImageKHR(eglGetCurrentDisplay(),

                                mEngine.nContext, EGL_NATIVE_BUFFER_ANDROID, (EGLClientBuffer)anb, attrs);

    if(mEngine.mTexture.pEGLImage == EGL_NO_IMAGE_KHR)

    {

        LOGI("Error: eglCreateImage() failed at %s:%in", __FILE__, __LINE__);

        return 0;

    }

    checkGlError("eglCreateImageKHR");

    LOGI("create Program.......");

    GLuint gProgram = createProgram(vertex_source, fragment_source);

     checkGlError("createProgram");

     if (!gProgram) {

             LOGE("Could not create program.");

             return false;

          }

     glUseProgram(gProgram);

     vPosition = glGetAttribLocation(gProgram, "glVertex");

         checkGlError("glGetAttribLocation glVertex");

     glEnableVertexAttribArray(vPosition);

 

    a_texCoord0 = glGetAttribLocation(gProgram, "a_texCoord0");

        checkGlError("glGetAttribLocation texCoord0");

     glEnableVertexAttribArray(a_texCoord0);

 

     s_tex0 = glGetUniformLocation(gProgram, "s_texture0");

        checkGlError("glGetAttribLocation texture");

         

     

     

        LOGI("glGen Textures.......");

    glGenTextures(1, &texID);

     

    glDisable(GL_BLEND);

    glDisable(GL_DEPTH_TEST);

    glDisable(GL_STENCIL_TEST);

    glDisable(GL_DITHER);

    checkGlError("glDisable");

//  glEnable(GL_TEXTURE_2D);

//  checkGlError("glEnable(GL_TEXTURE_2D)");

    glGenTextures(1,&texID);

    checkGlError("glGenTextures");

     glActiveTexture(GL_TEXTURE0);

    glBindTexture(GL_TEXTURE_2D, texID);

//  glPixelStorei(GL_PACK_ALIGNMENT, 1);

//      glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

     glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );

        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST  );

         

//       glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, mEngine.mTexture.nTextureWidth, mEngine.mTexture.nTextureHeight, 0,GL_RGBA, GL_UNSIGNED_BYTE, NULL);

     

//  glFinish();

    _glEGLImageTargetTexture2DOES(GL_TEXTURE_2D,mEngine.mTexture.pEGLImage);

         

     float w = float(emu_width)  / float(mEngine.mTexture.nTextureWidth);

     float h = float(emu_height) / float(mEngine.mTexture.nTextureHeight);

 

         g_pos=initFloatBuffer(vertices,12);

        g_texvbo=initFloatBuffer(texCoords,8);

         

        glViewport(0, 0,  mEngine.nScreen_Width, mEngine.nScreen_Height);

        return 1;

 

}

 

void Graphics::renderFrame() {

 

//  texture=(unsigned char*)ture;

    glClearColor(0.5f, 0.5f, 0.5f, 1);

    glClear( GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);

 

     glUniform1i(s_tex0, 0);

     glBindBuffer(GL_ARRAY_BUFFER, g_pos);

     glVertexAttribPointer(vPosition, 3, GL_FLOAT, GL_FALSE, 0, 0);

     glBindBuffer(GL_ARRAY_BUFFER, g_texvbo);

     glVertexAttribPointer(a_texCoord0, 2, GL_FLOAT, GL_FALSE, 0, 0);

    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

     

  eglSwapBuffers(mEngine.nDisplay, mEngine.nSurface);

  ｝

 

void* Graphics::begin(){

    GGLSurface t;

     graphicBuffer->lock(&t,GRALLOC_USAGE_SW_WRITE_OFTEN);

    return t.data;

}

void Graphics::end(){

     graphicBuffer->unlock();

     renderFrame();

}

 

 

使用时如下：

Graphics  render;

 

 

void *buffer=render.begin();

把数据填充到buffer里

render.end();

 

编译时包含头文件

LOCAL_C_INCLUDES +=

    $(ANDROID_SRC_HOME)/frameworks/base/core/jni/android/graphics 

    $(ANDROID_SRC_HOME)/frameworks/base/include/

    $(ANDROID_SRC_HOME)/hardware/libhardware/include

    $(ANDROID_SRC_HOME)/system/core/include

    $(ANDROID_SRC_HOME)/frameworks/base/native/include/

    $(ANDROID_SRC_HOME)/frameworks/base/opengl/include/

 

链接选项：

LOCAL_LDLIBS    := -llog -lGLESv2 -lEGL -landroid  -lui -landroid_runtime  -ljnigraphics

 

android  Opengles 里虽然没有PBO, 但是用Direct Texture能实现类似的功能。

 

direct textures 的使用介绍

http://snorp.net/2011/12/16/android-direct-texture.html

 

eglCreateImageKHR扩展的介绍

http://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_image_base.txt

描述：在opengles 编程时如果用glTexImage2D /glTexSubImage2D API的话，当渲染的图片很大时，速度会变得很慢的，因为运行时会发生数据拷贝的过程，而使用opengles 的扩展glEGLImageTargetTexture2DOES可以解决这个问题，用这个扩展要用到另一个扩展 eglCreateImageKHR 。