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September 25, 2015 21:33
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Opengl window with transparency in X11
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// originally from here: http://stackoverflow.com/questions/9363491/how-to-make-transparent-window-on-linux | |
/*------------------------------------------------------------------------ | |
* A demonstration of OpenGL in a ARGB window | |
* => support for composited window transparency | |
* | |
* (c) 2011 by Wolfgang 'datenwolf' Draxinger | |
* See me at comp.graphics.api.opengl and StackOverflow.com | |
* License agreement: This source code is provided "as is". You | |
* can use this source code however you want for your own personal | |
* use. If you give this source code to anybody else then you must | |
* leave this message in it. | |
* | |
* This program is based on the simplest possible | |
* Linux OpenGL program by FTB (see info below) | |
The simplest possible Linux OpenGL program? Maybe... | |
(c) 2002 by FTB. See me in comp.graphics.api.opengl | |
-- | |
<\___/> | |
/ O O \ | |
\_____/ FTB. | |
------------------------------------------------------------------------*/ | |
#include <stdlib.h> | |
#include <stdio.h> | |
#include <string.h> | |
#include <math.h> | |
#include <GL/gl.h> | |
#include <GL/glx.h> | |
#include <GL/glxext.h> | |
#include <X11/Xatom.h> | |
#include <X11/extensions/Xrender.h> | |
#include <X11/Xutil.h> | |
#define USE_CHOOSE_FBCONFIG | |
static void fatalError(const char *why) | |
{ | |
fprintf(stderr, "%s", why); | |
exit(0x666); | |
} | |
static int Xscreen; | |
static Atom del_atom; | |
static Colormap cmap; | |
static Display *Xdisplay; | |
static XVisualInfo *visual; | |
static XRenderPictFormat *pict_format; | |
static GLXFBConfig *fbconfigs, fbconfig; | |
static int numfbconfigs; | |
static GLXContext render_context; | |
static Window Xroot, window_handle; | |
static GLXWindow glX_window_handle; | |
static int width, height; | |
static int VisData[] = { | |
GLX_RENDER_TYPE, GLX_RGBA_BIT, | |
GLX_DRAWABLE_TYPE, GLX_WINDOW_BIT, | |
GLX_DOUBLEBUFFER, True, | |
GLX_RED_SIZE, 8, | |
GLX_GREEN_SIZE, 8, | |
GLX_BLUE_SIZE, 8, | |
GLX_ALPHA_SIZE, 8, | |
GLX_DEPTH_SIZE, 16, | |
None | |
}; | |
static int isExtensionSupported(const char *extList, const char *extension) | |
{ | |
const char *start; | |
const char *where, *terminator; | |
/* Extension names should not have spaces. */ | |
where = strchr(extension, ' '); | |
if ( where || *extension == '\0' ) | |
return 0; | |
/* It takes a bit of care to be fool-proof about parsing the | |
OpenGL extensions string. Don't be fooled by sub-strings, | |
etc. */ | |
for ( start = extList; ; ) { | |
where = strstr( start, extension ); | |
if ( !where ) | |
break; | |
terminator = where + strlen( extension ); | |
if ( where == start || *(where - 1) == ' ' ) | |
if ( *terminator == ' ' || *terminator == '\0' ) | |
return 1; | |
start = terminator; | |
} | |
return 0; | |
} | |
static Bool WaitForMapNotify(Display *d, XEvent *e, char *arg) | |
{ | |
return d && e && arg && (e->type == MapNotify) && (e->xmap.window == *(Window*)arg); | |
} | |
static void describe_fbconfig(GLXFBConfig fbconfig) | |
{ | |
int doublebuffer; | |
int red_bits, green_bits, blue_bits, alpha_bits, depth_bits; | |
glXGetFBConfigAttrib(Xdisplay, fbconfig, GLX_DOUBLEBUFFER, &doublebuffer); | |
glXGetFBConfigAttrib(Xdisplay, fbconfig, GLX_RED_SIZE, &red_bits); | |
glXGetFBConfigAttrib(Xdisplay, fbconfig, GLX_GREEN_SIZE, &green_bits); | |
glXGetFBConfigAttrib(Xdisplay, fbconfig, GLX_BLUE_SIZE, &blue_bits); | |
glXGetFBConfigAttrib(Xdisplay, fbconfig, GLX_ALPHA_SIZE, &alpha_bits); | |
glXGetFBConfigAttrib(Xdisplay, fbconfig, GLX_DEPTH_SIZE, &depth_bits); | |
fprintf(stderr, "FBConfig selected:\n" | |
"Doublebuffer: %s\n" | |
"Red Bits: %d, Green Bits: %d, Blue Bits: %d, Alpha Bits: %d, Depth Bits: %d\n", | |
doublebuffer == True ? "Yes" : "No", | |
red_bits, green_bits, blue_bits, alpha_bits, depth_bits); | |
} | |
static void createTheWindow() | |
{ | |
XEvent event; | |
int x,y, attr_mask; | |
XSizeHints hints; | |
XWMHints *startup_state; | |
XTextProperty textprop; | |
XSetWindowAttributes attr = {0,}; | |
static char *title = "FTB's little OpenGL example - ARGB extension by WXD"; | |
Xdisplay = XOpenDisplay(NULL); | |
if (!Xdisplay) { | |
fatalError("Couldn't connect to X server\n"); | |
} | |
Xscreen = DefaultScreen(Xdisplay); | |
Xroot = RootWindow(Xdisplay, Xscreen); | |
fbconfigs = glXChooseFBConfig(Xdisplay, Xscreen, VisData, &numfbconfigs); | |
fbconfig = 0; | |
for(int i = 0; i<numfbconfigs; i++) { | |
visual = (XVisualInfo*) glXGetVisualFromFBConfig(Xdisplay, fbconfigs[i]); | |
if(!visual) | |
continue; | |
pict_format = XRenderFindVisualFormat(Xdisplay, visual->visual); | |
if(!pict_format) | |
continue; | |
fbconfig = fbconfigs[i]; | |
if(pict_format->direct.alphaMask > 0) { | |
break; | |
} | |
} | |
if(!fbconfig) { | |
fatalError("No matching FB config found"); | |
} | |
describe_fbconfig(fbconfig); | |
/* Create a colormap - only needed on some X clients, eg. IRIX */ | |
cmap = XCreateColormap(Xdisplay, Xroot, visual->visual, AllocNone); | |
attr.colormap = cmap; | |
attr.background_pixmap = None; | |
attr.border_pixmap = None; | |
attr.border_pixel = 0; | |
attr.event_mask = | |
StructureNotifyMask | | |
EnterWindowMask | | |
LeaveWindowMask | | |
ExposureMask | | |
ButtonPressMask | | |
ButtonReleaseMask | | |
OwnerGrabButtonMask | | |
KeyPressMask | | |
KeyReleaseMask; | |
attr_mask = | |
CWBackPixmap| | |
CWColormap| | |
CWBorderPixel| | |
CWEventMask; | |
width = DisplayWidth(Xdisplay, DefaultScreen(Xdisplay))/2; | |
height = DisplayHeight(Xdisplay, DefaultScreen(Xdisplay))/2; | |
x=width/2, y=height/2; | |
window_handle = XCreateWindow( Xdisplay, | |
Xroot, | |
x, y, width, height, | |
0, | |
visual->depth, | |
InputOutput, | |
visual->visual, | |
attr_mask, &attr); | |
if( !window_handle ) { | |
fatalError("Couldn't create the window\n"); | |
} | |
#if USE_GLX_CREATE_WINDOW | |
int glXattr[] = { None }; | |
glX_window_handle = glXCreateWindow(Xdisplay, fbconfig, window_handle, glXattr); | |
if( !glX_window_handle ) { | |
fatalError("Couldn't create the GLX window\n"); | |
} | |
#else | |
glX_window_handle = window_handle; | |
#endif | |
textprop.value = (unsigned char*)title; | |
textprop.encoding = XA_STRING; | |
textprop.format = 8; | |
textprop.nitems = strlen(title); | |
hints.x = x; | |
hints.y = y; | |
hints.width = width; | |
hints.height = height; | |
hints.flags = USPosition|USSize; | |
startup_state = XAllocWMHints(); | |
startup_state->initial_state = NormalState; | |
startup_state->flags = StateHint; | |
XSetWMProperties(Xdisplay, window_handle,&textprop, &textprop, | |
NULL, 0, | |
&hints, | |
startup_state, | |
NULL); | |
XFree(startup_state); | |
XMapWindow(Xdisplay, window_handle); | |
XIfEvent(Xdisplay, &event, WaitForMapNotify, (char*)&window_handle); | |
if ((del_atom = XInternAtom(Xdisplay, "WM_DELETE_WINDOW", 0)) != None) { | |
XSetWMProtocols(Xdisplay, window_handle, &del_atom, 1); | |
} | |
} | |
static int ctxErrorHandler( Display *dpy, XErrorEvent *ev ) | |
{ | |
fputs("Error at context creation", stderr); | |
return 0; | |
} | |
static void createTheRenderContext() | |
{ | |
int dummy; | |
if (!glXQueryExtension(Xdisplay, &dummy, &dummy)) { | |
fatalError("OpenGL not supported by X server\n"); | |
} | |
#if USE_GLX_CREATE_CONTEXT_ATTRIB | |
#define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091 | |
#define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092 | |
render_context = NULL; | |
if( isExtensionSupported( glXQueryExtensionsString(Xdisplay, DefaultScreen(Xdisplay)), "GLX_ARB_create_context" ) ) { | |
typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*); | |
glXCreateContextAttribsARBProc glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc)glXGetProcAddressARB( (const GLubyte *) "glXCreateContextAttribsARB" ); | |
if( glXCreateContextAttribsARB ) { | |
int context_attribs[] = | |
{ | |
GLX_CONTEXT_MAJOR_VERSION_ARB, 3, | |
GLX_CONTEXT_MINOR_VERSION_ARB, 0, | |
//GLX_CONTEXT_FLAGS_ARB , GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB, | |
None | |
}; | |
int (*oldHandler)(Display*, XErrorEvent*) = XSetErrorHandler(&ctxErrorHandler); | |
render_context = glXCreateContextAttribsARB( Xdisplay, fbconfig, 0, True, context_attribs ); | |
XSync( Xdisplay, False ); | |
XSetErrorHandler( oldHandler ); | |
fputs("glXCreateContextAttribsARB failed", stderr); | |
} else { | |
fputs("glXCreateContextAttribsARB could not be retrieved", stderr); | |
} | |
} else { | |
fputs("glXCreateContextAttribsARB not supported", stderr); | |
} | |
if(!render_context) | |
{ | |
#else | |
{ | |
#endif | |
render_context = glXCreateNewContext(Xdisplay, fbconfig, GLX_RGBA_TYPE, 0, True); | |
if (!render_context) { | |
fatalError("Failed to create a GL context\n"); | |
} | |
} | |
if (!glXMakeContextCurrent(Xdisplay, glX_window_handle, glX_window_handle, render_context)) { | |
fatalError("glXMakeCurrent failed for window\n"); | |
} | |
} | |
static int updateTheMessageQueue() | |
{ | |
XEvent event; | |
XConfigureEvent *xc; | |
while (XPending(Xdisplay)) | |
{ | |
XNextEvent(Xdisplay, &event); | |
switch (event.type) | |
{ | |
case ClientMessage: | |
if (event.xclient.data.l[0] == del_atom) | |
{ | |
return 0; | |
} | |
break; | |
case ConfigureNotify: | |
xc = &(event.xconfigure); | |
width = xc->width; | |
height = xc->height; | |
break; | |
} | |
} | |
return 1; | |
} | |
/* 6----7 | |
/| /| | |
3----2 | | |
| 5--|-4 | |
|/ |/ | |
0----1 | |
*/ | |
GLfloat cube_vertices[][8] = { | |
/* X Y Z Nx Ny Nz S T */ | |
{-1.0, -1.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0}, // 0 | |
{ 1.0, -1.0, 1.0, 0.0, 0.0, 1.0, 1.0, 0.0}, // 1 | |
{ 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0}, // 2 | |
{-1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0}, // 3 | |
{ 1.0, -1.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0}, // 4 | |
{-1.0, -1.0, -1.0, 0.0, 0.0, -1.0, 1.0, 0.0}, // 5 | |
{-1.0, 1.0, -1.0, 0.0, 0.0, -1.0, 1.0, 1.0}, // 6 | |
{ 1.0, 1.0, -1.0, 0.0, 0.0, -1.0, 0.0, 1.0}, // 7 | |
{-1.0, -1.0, -1.0, -1.0, 0.0, 0.0, 0.0, 0.0}, // 5 | |
{-1.0, -1.0, 1.0, -1.0, 0.0, 0.0, 1.0, 0.0}, // 0 | |
{-1.0, 1.0, 1.0, -1.0, 0.0, 0.0, 1.0, 1.0}, // 3 | |
{-1.0, 1.0, -1.0, -1.0, 0.0, 0.0, 0.0, 1.0}, // 6 | |
{ 1.0, -1.0, 1.0, 1.0, 0.0, 0.0, 0.0, 0.0}, // 1 | |
{ 1.0, -1.0, -1.0, 1.0, 0.0, 0.0, 1.0, 0.0}, // 4 | |
{ 1.0, 1.0, -1.0, 1.0, 0.0, 0.0, 1.0, 1.0}, // 7 | |
{ 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 0.0, 1.0}, // 2 | |
{-1.0, -1.0, -1.0, 0.0, -1.0, 0.0, 0.0, 0.0}, // 5 | |
{ 1.0, -1.0, -1.0, 0.0, -1.0, 0.0, 1.0, 0.0}, // 4 | |
{ 1.0, -1.0, 1.0, 0.0, -1.0, 0.0, 1.0, 1.0}, // 1 | |
{-1.0, -1.0, 1.0, 0.0, -1.0, 0.0, 0.0, 1.0}, // 0 | |
{-1.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 0.0}, // 3 | |
{ 1.0, 1.0, 1.0, 0.0, 1.0, 0.0, 1.0, 0.0}, // 2 | |
{ 1.0, 1.0, -1.0, 0.0, 1.0, 0.0, 1.0, 1.0}, // 7 | |
{-1.0, 1.0, -1.0, 0.0, 1.0, 0.0, 0.0, 1.0}, // 6 | |
}; | |
static void draw_cube(void) | |
{ | |
glEnableClientState(GL_VERTEX_ARRAY); | |
glEnableClientState(GL_NORMAL_ARRAY); | |
glEnableClientState(GL_TEXTURE_COORD_ARRAY); | |
glVertexPointer(3, GL_FLOAT, sizeof(GLfloat) * 8, &cube_vertices[0][0]); | |
glNormalPointer(GL_FLOAT, sizeof(GLfloat) * 8, &cube_vertices[0][3]); | |
glTexCoordPointer(2, GL_FLOAT, sizeof(GLfloat) * 8, &cube_vertices[0][6]); | |
glDrawArrays(GL_QUADS, 0, 24); | |
} | |
float const light0_dir[]={0,1,0,0}; | |
float const light0_color[]={78./255., 80./255., 184./255.,1}; | |
float const light1_dir[]={-1,1,1,0}; | |
float const light1_color[]={255./255., 220./255., 97./255.,1}; | |
float const light2_dir[]={0,-1,0,0}; | |
float const light2_color[]={31./255., 75./255., 16./255.,1}; | |
static void redrawTheWindow() | |
{ | |
float const aspect = (float)width / (float)height; | |
static float a=0; | |
static float b=0; | |
static float c=0; | |
glDrawBuffer(GL_BACK); | |
glViewport(0, 0, width, height); | |
// Clear with alpha = 0.0, i.e. full transparency | |
glClearColor(0.0, 0.0, 0.0, 0.0); | |
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); | |
glMatrixMode(GL_PROJECTION); | |
glLoadIdentity(); | |
glFrustum(-aspect, aspect, -1, 1, 2.5, 10); | |
glMatrixMode(GL_MODELVIEW); | |
glLoadIdentity(); | |
glEnable(GL_DEPTH_TEST); | |
glEnable(GL_CULL_FACE); | |
glEnable(GL_BLEND); | |
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); | |
glLightfv(GL_LIGHT0, GL_POSITION, light0_dir); | |
glLightfv(GL_LIGHT0, GL_DIFFUSE, light0_color); | |
glLightfv(GL_LIGHT1, GL_POSITION, light1_dir); | |
glLightfv(GL_LIGHT1, GL_DIFFUSE, light1_color); | |
glLightfv(GL_LIGHT2, GL_POSITION, light2_dir); | |
glLightfv(GL_LIGHT2, GL_DIFFUSE, light2_color); | |
glTranslatef(0., 0., -5.); | |
glRotatef(a, 1, 0, 0); | |
glRotatef(b, 0, 1, 0); | |
glRotatef(c, 0, 0, 1); | |
glEnable(GL_LIGHT0); | |
glEnable(GL_LIGHT1); | |
glEnable(GL_LIGHTING); | |
glEnable(GL_COLOR_MATERIAL); | |
glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE); | |
glColor4f(1., 1., 1., 0.5); | |
glCullFace(GL_FRONT); | |
draw_cube(); | |
glCullFace(GL_BACK); | |
draw_cube(); | |
a = fmod(a+0.1, 360.); | |
b = fmod(b+0.5, 360.); | |
c = fmod(c+0.25, 360.); | |
glXSwapBuffers(Xdisplay, glX_window_handle); | |
} | |
int main(int argc, char *argv[]) | |
{ | |
createTheWindow(); | |
createTheRenderContext(); | |
while (updateTheMessageQueue()) { | |
redrawTheWindow(); | |
} | |
return 0; | |
} |
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