我正在尝试将应用程序移植到我要设计的嵌入式系统上。嵌入式系统基于Raspberry Pi Zero W-，并使用自定义的Yocto构建。
据我了解，要移植的应用程序是使用SDL / OpenGLES编写的。我很难理解如何进行类似于以下描述的连接：
SDL APP -----> XServer ($DISPLAY) -------> Framebuffer /dev/fb1 ($FRAMEBUFFER)
系统有两个显示器：/dev/fb0上一个HDMI和/dev/fb1上一个TFT。我正在尝试在TFT上运行SDL应用程序。以下是我要做的步骤：
首先，在DISPLAY=:1上启动连接到/dev/fb1的XServer：
FRAMEBUFFER=/dev/fb1 xinit /etc/X11/Xsession -- /usr/bin/Xorg :1 -br -pn -nolisten tcp -dpi 100
第一步似乎很有效。我可以在TFT屏幕上看到LXDE正在启动。检查显示，我得到正确的显示分辨率：
~/projects# DISPLAY=:1 xrandr -q
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 320 x 240, current 320 x 240, maximum 320 x 240
default connected 320x240+0+0 0mm x 0mm
320x240 0.00*
第二，我想使用x11启动SDL编写的应用程序。我认为这应该可以在TFT上看到应用程序。为此，我尝试：
SDL_VIDEODRIVER=x11 SDL_WINDOWID=1 DISPLAY=:1 ./SDL_App
无论我选择哪个显示号，它都从我的HDMI显示器而不是TFT上启动。因此，现在我正在考虑编写应用程序的人在应用程序代码中对某些内容进行了硬编码：
void init_ogl(void)
{
int32_t success = 0;
EGLBoolean result;
EGLint num_config;
static EGL_DISPMANX_WINDOW_T nativewindow;
DISPMANX_ELEMENT_HANDLE_T dispman_element;
DISPMANX_DISPLAY_HANDLE_T dispman_display;
DISPMANX_UPDATE_HANDLE_T dispman_update;
VC_DISPMANX_ALPHA_T alpha;
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
};
EGLConfig config;
// Get an EGL display connection
display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
assert(display!=EGL_NO_DISPLAY);
// Initialize the EGL display connection
result = eglInitialize(display, NULL, NULL);
assert(EGL_FALSE != result);
// Get an appropriate EGL frame buffer configuration
result = eglChooseConfig(display, attribute_list, &config, 1, &num_config);
assert(EGL_FALSE != result);
// Create an EGL rendering context
context = eglCreateContext(display, config, EGL_NO_CONTEXT, NULL);
assert(context!=EGL_NO_CONTEXT);
// Create an EGL window surface
success = graphics_get_display_size( 0 /* LCD */ , &screen_width, &screen_height);
printf ("Screen width= %d\n", screen_width);
printf ("Screen height= %d\n", screen_height);
assert( success >= 0 );
int32_t zoom = screen_width / GAMEBOY_WIDTH;
int32_t zoom2 = screen_height / GAMEBOY_HEIGHT;
if (zoom2 < zoom)
zoom = zoom2;
int32_t display_width = GAMEBOY_WIDTH * zoom;
int32_t display_height = GAMEBOY_HEIGHT * zoom;
int32_t display_offset_x = (screen_width / 2) - (display_width / 2);
int32_t display_offset_y = (screen_height / 2) - (display_height / 2);
dst_rect.x = 0;
dst_rect.y = 0;
dst_rect.width = screen_width;
dst_rect.height = screen_height;
src_rect.x = 0;
src_rect.y = 0;
src_rect.width = screen_width << 16;
src_rect.height = screen_height << 16;
dispman_display = vc_dispmanx_display_open( 0 /* LCD */ );
dispman_update = vc_dispmanx_update_start( 0 );
alpha.flags = DISPMANX_FLAGS_ALPHA_FIXED_ALL_PIXELS;
alpha.opacity = 255;
alpha.mask = 0;
dispman_element = vc_dispmanx_element_add ( dispman_update, dispman_display,
0/*layer*/, &dst_rect, 0/*src*/,
&src_rect, DISPMANX_PROTECTION_NONE, &alpha, 0/*clamp*/, DISPMANX_NO_ROTATE/*transform*/);
nativewindow.element = dispman_element;
nativewindow.width = screen_width;
nativewindow.height = screen_height;
vc_dispmanx_update_submit_sync( dispman_update );
surface = eglCreateWindowSurface( display, config, &nativewindow, NULL );
assert(surface != EGL_NO_SURFACE);
// Connect the context to the surface
result = eglMakeCurrent(display, surface, surface, context);
assert(EGL_FALSE != result);
eglSwapInterval(display, 1);
glGenTextures(1, &theGBTexture);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, theGBTexture);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 256, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid*) NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrthof(0.0f, screen_width, screen_height, 0.0f, -1.0f, 1.0f);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glViewport(0.0f, 0.0f, screen_width, screen_height);
quadVerts[0] = display_offset_x;
quadVerts[1] = display_offset_y;
quadVerts[2] = display_offset_x + display_width;
quadVerts[3] = display_offset_y;
quadVerts[4] = display_offset_x + display_width;
quadVerts[5] = display_offset_y + display_height;
quadVerts[6] = display_offset_x;
quadVerts[7] = display_offset_y + display_height;
glVertexPointer(2, GL_SHORT, 0, quadVerts);
glEnableClientState(GL_VERTEX_ARRAY);
glTexCoordPointer(2, GL_FLOAT, 0, kQuadTex);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glClear(GL_COLOR_BUFFER_BIT);
}
void init_sdl(void)
{
if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_GAMECONTROLLER) < 0)
{
Log("SDL Error Init: %s", SDL_GetError());
}
theWindow = SDL_CreateWindow("Gearboy", 0, 0, 0, 0, 0);
if (theWindow == NULL)
{
Log("SDL Error Video: %s", SDL_GetError());
}
...
}
乍一看，我发现了两行：vc_dispmanx_display_open( 0 /* LCD */ );和graphics_get_display_size( 0 /* LCD */ , &screen_width, &screen_height);。我尝试将显示参数更改为1，以为它引用了DISPLAY=:1，但是它什么也没做。我添加了用于屏幕分辨率的日志，得到1920x1080，这是HDMI显示器的分辨率。我认为代码中的EGL部分一定缺少某些内容。我现在该怎么办？我的逻辑足够合理还是我缺少一些东西？
任何要求，请告诉我。任何有关此问题的指导都将受到赞赏。
编辑：我看到有些人使用以下命令，但raspberry pi zero找不到fb函数的EGL / eglvivante.h，因此我无法对其进行编译：
int fbnum = 1; // fbnum is an integer for /dev/fb1 fbnum = 1
EGLNativeDisplayType native_display = fbGetDisplayByIndex(fbnum);
EGLNativeWindowType native_window = fbCreateWindow(native_display, 0, 0, 0, 0);
display = eglGetDisplay(native_display);