運行環境：raspberry pi3 官方jessie系統，QT 5.3.2本文應用場景：FFMPEG解碼視頻獲得圖片幀，使用opengl進行顯示。
代碼：glplayer.h
#ifndef GLPLAYER_H
#define GLPLAYER_H
#include <QObject>
#include <stdio.h>
#include <math.h>
#include <sys/time.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <GLES2/gl2.h>
#include <cassert>
#include "bcm_host.h"
typedef struct
{
// Handle to a program object
GLuint programObject;
// Attribute locations
GLint positionLoc;
GLint texCoordLoc;
// Sampler location
GLint samplerLoc;
// Texture handle
GLuint textureId;
} UserData;
typedef struct CUBE_STATE_T
{
uint32_t width;
uint32_t height;
EGLDisplay display;
EGLSurface surface;
EGLContext context;
EGL_DISPMANX_WINDOW_T nativewindow;
UserData *user_data;
DISPMANX_ELEMENT_HANDLE_T dispman_element;
DISPMANX_DISPLAY_HANDLE_T dispman_display;
DISPMANX_UPDATE_HANDLE_T dispman_update;
} CUBE_STATE_T;
class GlPlayer{
private:
GLuint createSimpleTexture2D();
GLuint loadShader(GLenum type, const char *shaderSrc);
GLuint loadProgram (const char *vertShaderSrc, const char *fragShaderSrc);
void initEGL( int width, int height);
int init();
void releaseEGL();
public:
GlPlayer(int width, int height);
~GlPlayer();
void draw(char * image);
public:
int m_width;
int m_height;
CUBE_STATE_T *p_state;
UserData *user_data;
};
#endif // GLPLAYER_H#include "glplayer.h"
#include <QApplication>
#include <QDesktopWidget>
#include <QTime>
GlPlayer::GlPlayer(int width, int height) :
user_data(new UserData()),
p_state(new CUBE_STATE_T()),
m_width(width),
m_height(height)
{
p_state->user_data = user_data;
initEGL(m_width, m_height);
if(!init()) exit(1);
}
GlPlayer::~GlPlayer(){
fprintf(stderr, "~GlPlayer()\n");
releaseEGL();
if(user_data != NULL) delete user_data;
if(p_state != NULL) delete p_state;
}
// Create a simple width x height texture image with four different colors
//
GLuint GlPlayer::createSimpleTexture2D(){
// Texture object handle
GLuint textureId;
// Use tightly packed data
glPixelStorei ( GL_UNPACK_ALIGNMENT, 1 );
// Generate a texture object
glGenTextures ( 1, &textureId );
// Bind the texture object
glBindTexture ( GL_TEXTURE_2D, textureId );
// Set the filtering mode
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
return textureId;
}
// Create a shader object, load the shader source, and
// compile the shader.
//
GLuint GlPlayer::loadShader(GLenum type, const char *shaderSrc){
GLuint shader;
GLint compiled;
// Create the shader object
shader = glCreateShader(type);
if(shader == 0)
return 0;
// Load the shader source
glShaderSource(shader, 1, &shaderSrc, NULL);
// Compile the shader
glCompileShader(shader);
// Check the compile status
glGetShaderiv(shader, GL_COMPILE_STATUS, &compiled);
if(!compiled){
GLint infoLen = 0;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &infoLen);
if(infoLen > 1){
char* infoLog = (char*)malloc(sizeof(char) * infoLen);
glGetShaderInfoLog(shader, infoLen, NULL, infoLog);
fprintf(stderr, "Error compiling shader:\n%s\n", infoLog);
free(infoLog);
}
glDeleteShader(shader);
return 0;
}
return shader;
}
GLuint GlPlayer::loadProgram ( const char *vertShaderSrc, const char *fragShaderSrc ){
GLuint vertexShader;
GLuint fragmentShader;
GLuint programObject;
GLint linked;
// Load the vertex/fragment shaders
vertexShader = loadShader ( GL_VERTEX_SHADER, vertShaderSrc );
if ( vertexShader == 0 ) return 0;
fragmentShader = loadShader ( GL_FRAGMENT_SHADER, fragShaderSrc );
if ( fragmentShader == 0 ){
glDeleteShader( vertexShader );
return 0;
}
// Create the program object
programObject = glCreateProgram ();
if ( programObject == 0 ) return 0;
glAttachShader ( programObject, vertexShader );
glAttachShader ( programObject, fragmentShader );
// Link the program
glLinkProgram ( programObject );
// Check the link status
glGetProgramiv ( programObject, GL_LINK_STATUS, &linked );
if ( !linked ){
GLint infoLen = 0;
glGetProgramiv ( programObject, GL_INFO_LOG_LENGTH, &infoLen );
if ( infoLen > 1 ){
char* infoLog = (char*)malloc (sizeof(char) * infoLen );
glGetProgramInfoLog ( programObject, infoLen, NULL, infoLog );
fprintf (stderr, "Error linking program:\n%s\n", infoLog );
free ( infoLog );
}
glDeleteProgram ( programObject );
return 0;
}
// Free up no longer needed shader resources
glDeleteShader ( vertexShader );
glDeleteShader ( fragmentShader );
return programObject;
}
void GlPlayer::initEGL(int width, int height){
int32_t success = 0;
EGLBoolean result;
EGLint num_config;
bcm_host_init();
VC_RECT_T dst_rect;
VC_RECT_T src_rect;
static const EGLint attribute_list[] =
{
EGL_RED_SIZE, 8,
EGL_GREEN_SIZE, 8,
EGL_BLUE_SIZE, 8,
EGL_ALPHA_SIZE, 8,
EGL_SURFACE_TYPE, EGL_WINDOW_BIT,
EGL_NONE
};
static const EGLint context_attributes[] =
{
EGL_CONTEXT_CLIENT_VERSION, 2,
EGL_NONE
};
EGLConfig config;
// get an EGL display connection
p_state->display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
// initialize the EGL display connection
result = eglInitialize(p_state->display, NULL, NULL);
// get an appropriate EGL frame buffer configuration
result = eglChooseConfig(p_state->display, attribute_list, &config, 1, &num_config);
assert(EGL_FALSE != result);
// get an appropriate EGL frame buffer configuration
result = eglBindAPI(EGL_OPENGL_ES_API);
assert(EGL_FALSE != result);
// create an EGL rendering context
p_state->context = eglCreateContext(p_state->display, config, EGL_NO_CONTEXT, context_attributes);
assert(p_state->context!=EGL_NO_CONTEXT);
// create an EGL window surface
success = graphics_get_display_size(0 /* LCD */, &p_state->width, &p_state->height);
assert( success >= 0 );
p_state->width = width;
p_state->height = height;
QDesktopWidget *dwsktopwidget = QApplication::desktop();
QRect deskrect = dwsktopwidget->availableGeometry();
dst_rect.x = 0;
dst_rect.y = 0;
dst_rect.width = deskrect.width();
dst_rect.height = deskrect.height();
src_rect.x = 0;
src_rect.y = 0;
src_rect.width = p_state->width;
src_rect.height = p_state->height;
p_state->dispman_display = vc_dispmanx_display_open( 0 /* LCD */);
p_state->dispman_update = vc_dispmanx_update_start( 0 );
p_state->dispman_element =
vc_dispmanx_element_add(p_state->dispman_update, p_state->dispman_display,
0/*layer*/, &dst_rect, 0/*src*/,
&src_rect, DISPMANX_PROTECTION_NONE,
0 /*alpha*/, 0/*clamp*/, DISPMANX_NO_ROTATE/*transform*/);
p_state->nativewindow.element = p_state->dispman_element;
p_state->nativewindow.width = deskrect.width();
p_state->nativewindow.height = deskrect.height();
vc_dispmanx_update_submit_sync( p_state->dispman_update );
p_state->surface = eglCreateWindowSurface( p_state->display, config, &(p_state->nativewindow), NULL );
assert(p_state->surface != EGL_NO_SURFACE);
// connect the context to the surface
result = eglMakeCurrent(p_state->display, p_state->surface, p_state->surface, p_state->context);
assert(EGL_FALSE != result);
}
///
// Initialize the shader and program object
//
int GlPlayer::init(){
UserData *userData = p_state->user_data;
memset(userData, 0, sizeof(UserData));
char vShaderStr[] =
"attribute vec4 a_position; \n"
"attribute vec2 a_texCoord; \n"
"varying vec2 v_texCoord; \n"
"void main() \n"
"{ \n"
" gl_Position = a_position; \n"
" v_texCoord = a_texCoord; \n"
"} \n";
char fShaderStr[] =
"precision mediump float; \n"
"varying vec2 v_texCoord; \n"
"uniform sampler2D s_texture; \n"
"void main() \n"
"{ \n"
" gl_FragColor = texture2D( s_texture, v_texCoord );\n"
"} \n";
// Load the shaders and get a linked program object
userData->programObject = loadProgram ( vShaderStr, fShaderStr );
// Get the attribute locations
userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" );
userData->texCoordLoc = glGetAttribLocation ( userData->programObject, "a_texCoord" );
// Get the sampler location
userData->samplerLoc = glGetUniformLocation ( userData->programObject, "s_texture" );
// Load the texture
userData->textureId = createSimpleTexture2D ();
// Set the viewport
QDesktopWidget *dwsktopwidget = QApplication::desktop();
QRect deskrect = dwsktopwidget->availableGeometry();
glViewport (0, 0, deskrect.width(), deskrect.height());
glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
// Clear the color buffer
glClear ( GL_COLOR_BUFFER_BIT );
// Use the program object
glUseProgram ( userData->programObject );
// Bind the texture
glActiveTexture ( GL_TEXTURE0 );
glBindTexture ( GL_TEXTURE_2D, userData->textureId );
glEnableVertexAttribArray ( userData->positionLoc );
glEnableVertexAttribArray ( userData->texCoordLoc );
// Set the sampler texture unit to 0
glUniform1i ( userData->samplerLoc, 0 );
return GL_TRUE;
}
// Draw triangles using the shader pair created in Init()
//
void GlPlayer::draw(char * image){
if(image == NULL){
printf("image error\n");
return;
}
if(p_state == NULL){
printf("p_state error\n");
return;
}
UserData *userData = p_state->user_data;
if(userData == NULL){
printf("userData error\n");
return;
}
printf("draw image, size %dx%d\n",m_width,m_height);
#if 0
QImage img((uchar *)image,m_width,m_height,QImage::Format_ARGB32);
QDateTime time = QDateTime::currentDateTime();
QString filename = "/home/pi/image/"+time.toString("yyyy-MM-dd-hh-mm-ss")+".png";
img.save(filename);
#endif
glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGBA, m_width, m_height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
GLfloat vVertices[] = { -1.0f, 1.0f, 0.0f, // Position 0
0.0f, 0.0f, // TexCoord 0
-1.0f, -1.0f, 0.0f, // Position 1
0.0f, 1.0f, // TexCoord 1
1.0f, -1.0f, 0.0f, // Position 2
1.0f, 1.0f, // TexCoord 2
1.0f, 1.0f, 0.0f, // Position 3
1.0f, 0.0f // TexCoord 3
};
GLushort indices[] = { 0, 1, 2, 0, 2, 3 };
//GLushort indices[] = {1, 0, 3, 0, 2, 0, 1 };
// Load the vertex position
glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), vVertices );
// Load the texture coordinate
glVertexAttribPointer ( userData->texCoordLoc, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), &vVertices[3] );
glDrawElements ( GL_TRIANGLES, 6, GL_UNSIGNED_SHORT, indices );
eglSwapBuffers(p_state->display, p_state->surface);
}
void GlPlayer::releaseEGL(){
eglMakeCurrent(p_state->display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
eglDestroySurface(p_state->display, p_state->surface);
eglDestroyContext(p_state->display, p_state->context);
eglTerminate(p_state->display);
}調用方式：
GlPlayer* glplayer = new GlPlayer(width, height);
glplayer->draw(image_addr);
delete glplayer;
參考:
https://jan.newmarch.name/LinuxSound/Diversions/RaspberryPiOpenGL/