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To: sdl@libsdl.org
From: Christian Walther <cwalther@gmx.ch>
Date: Thu, 15 Dec 2005 21:19:53 +0100
Subject: [SDL] More mouse enhancements for Mac OS X
The attached patch brings two more enhancements to mouse handling on Mac
OS X (Quartz):
1. Currently, after launching an SDL application, SDL's notion of the
mouse position is stuck in the top left corner (0,0) until the first
time the mouse is moved. That's because the UpdateMouse() function isn't
implemented in the Quartz driver. This patch adds it.
2. When grabbing input while the mouse cursor is hidden, the function
CGAssociateMouseAndMouseCursorPosition(0) is called, which prevents the
system's notion of the mouse location from moving (and therefore leaving
the SDL window) even when the mouse is moved. However, apparently the
Wacom tablet driver (and maybe other special pointing device drivers)
doesn't care about that setting and still allows the mouse location to
go outside of the window. Interestingly, the system cursor, which is
made visible by the existing code in SDL in that case, does not follow
the mouse location, but appears in the middle of the SDL window. The
mouse location being outside of the window however means that mouse
button events go to background applications (or the dock or whatever is
there), which is very confusing to the user who sees no cursor outside
of the SDL window.
I have not found any way of intercepting these events (and that's
probably by design, as "normal" applications shouldn't prevent the user
from bringing other applications' windows to the front by clicking on
them). An idea would be placing a fully transparent, screen-filling
window in front of everything, but I fear that this might affect
rendering performance (by doing unnecessary compositing, using up
memory, or whatever).
The deluxe solution to the problem would be talking to the tablet
driver using AppleEvents to tell it to constrain its mapped area to the
window (see Wacom's "TabletEventDemo" sample app,
http://www.wacomeng.com/devsupport/mac/downloads.html), but I think that
the bloat that solution would add to SDL would outweigh its usefulness.
What I did instead in my patch is reassociating mouse and cursor when
the mouse leaves the window while an invisible grab is in effect, and
restoring the grab when the window is entered. That way, the grab can
still be effectively broken by a tablet, but at least it's obvious to
the user that it is broken. That change is minimal - it doesn't affect
operation with a mouse (or a trackpad), and the code that it adds is not
executed on every PumpEvents() call, only when entering and leaving the
window.
Unless there are any concerns about the patch, please apply. Feel free
to shorten the lengthy comment in SDL_QuartzEvents.m if you think it's
too verbose.
Thanks
-Christian
author | Ryan C. Gordon <icculus@icculus.org> |
---|---|
date | Mon, 02 Jan 2006 00:31:00 +0000 |
parents | 355632dca928 |
children | f12379c41042 |
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<HTML ><HEAD ><TITLE >Using OpenGL With SDL</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ "><LINK REL="HOME" TITLE="SDL Library Documentation" HREF="index.html"><LINK REL="UP" TITLE="Graphics and Video" HREF="guidevideo.html"><LINK REL="PREVIOUS" TITLE="Graphics and Video" HREF="guidevideo.html"><LINK REL="NEXT" TITLE="Input handling" HREF="guideinput.html"></HEAD ><BODY CLASS="SECT1" BGCOLOR="#FFF8DC" TEXT="#000000" LINK="#0000ee" VLINK="#551a8b" ALINK="#ff0000" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >SDL Library Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="guidevideo.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Chapter 2. Graphics and Video</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="guideinput.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="GUIDEVIDEOOPENGL" ></A >Using OpenGL With SDL</H1 ><P >SDL has the ability to create and use OpenGL contexts on several platforms(Linux/X11, Win32, BeOS, MacOS Classic/Toolbox, MacOS X, FreeBSD/X11 and Solaris/X11). This allows you to use SDL's audio, event handling, threads and times in your OpenGL applications (a function often performed by GLUT).</P ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN103" ></A >Initialisation</H2 ><P >Initialising SDL to use OpenGL is not very different to initialising SDL normally. There are three differences; you must pass <TT CLASS="LITERAL" >SDL_OPENGL</TT > to <A HREF="sdlsetvideomode.html" ><TT CLASS="FUNCTION" >SDL_SetVideoMode</TT ></A >, you must specify several GL attributes (depth buffer size, framebuffer sizes) using <A HREF="sdlglsetattribute.html" ><TT CLASS="FUNCTION" >SDL_GL_SetAttribute</TT ></A > and finally, if you wish to use double buffering you must specify it as a GL attribute, <SPAN CLASS="emphasis" ><I CLASS="EMPHASIS" >not</I ></SPAN > by passing the <TT CLASS="LITERAL" >SDL_DOUBLEBUF</TT > flag to <TT CLASS="FUNCTION" >SDL_SetVideoMode</TT >.</P ><DIV CLASS="EXAMPLE" ><A NAME="AEN114" ></A ><P ><B >Example 2-7. Initializing SDL with OpenGL</B ></P ><PRE CLASS="PROGRAMLISTING" > /* Information about the current video settings. */ const SDL_VideoInfo* info = NULL; /* Dimensions of our window. */ int width = 0; int height = 0; /* Color depth in bits of our window. */ int bpp = 0; /* Flags we will pass into SDL_SetVideoMode. */ int flags = 0; /* First, initialize SDL's video subsystem. */ if( SDL_Init( SDL_INIT_VIDEO ) < 0 ) { /* Failed, exit. */ fprintf( stderr, "Video initialization failed: %s\n", SDL_GetError( ) ); quit_tutorial( 1 ); } /* Let's get some video information. */ info = SDL_GetVideoInfo( ); if( !info ) { /* This should probably never happen. */ fprintf( stderr, "Video query failed: %s\n", SDL_GetError( ) ); quit_tutorial( 1 ); } /* * Set our width/height to 640/480 (you would * of course let the user decide this in a normal * app). We get the bpp we will request from * the display. On X11, VidMode can't change * resolution, so this is probably being overly * safe. Under Win32, ChangeDisplaySettings * can change the bpp. */ width = 640; height = 480; bpp = info->vfmt->BitsPerPixel; /* * Now, we want to setup our requested * window attributes for our OpenGL window. * We want *at least* 5 bits of red, green * and blue. We also want at least a 16-bit * depth buffer. * * The last thing we do is request a double * buffered window. '1' turns on double * buffering, '0' turns it off. * * Note that we do not use SDL_DOUBLEBUF in * the flags to SDL_SetVideoMode. That does * not affect the GL attribute state, only * the standard 2D blitting setup. */ SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 ); SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); /* * We want to request that SDL provide us * with an OpenGL window, in a fullscreen * video mode. * * EXERCISE: * Make starting windowed an option, and * handle the resize events properly with * glViewport. */ flags = SDL_OPENGL | SDL_FULLSCREEN; /* * Set the video mode */ if( SDL_SetVideoMode( width, height, bpp, flags ) == 0 ) { /* * This could happen for a variety of reasons, * including DISPLAY not being set, the specified * resolution not being available, etc. */ fprintf( stderr, "Video mode set failed: %s\n", SDL_GetError( ) ); quit_tutorial( 1 ); }</PRE ></DIV ></DIV ><DIV CLASS="SECT2" ><H2 CLASS="SECT2" ><A NAME="AEN117" ></A >Drawing</H2 ><P >Apart from initialisation, using OpenGL within SDL is the same as using OpenGL with any other API, e.g. GLUT. You still use all the same function calls and data types. However if you are using a double-buffered display, then you must use <A HREF="sdlglswapbuffers.html" ><TT CLASS="FUNCTION" >SDL_GL_SwapBuffers()</TT ></A > to swap the buffers and update the display. To request double-buffering with OpenGL, use <A HREF="sdlglsetattribute.html" ><TT CLASS="FUNCTION" >SDL_GL_SetAttribute</TT ></A > with <TT CLASS="LITERAL" >SDL_GL_DOUBLEBUFFER</TT >, and use <A HREF="sdlglgetattribute.html" ><TT CLASS="FUNCTION" >SDL_GL_GetAttribute</TT ></A > to see if you actually got it.</P ><P >A full example code listing is now presented below.</P ><DIV CLASS="EXAMPLE" ><A NAME="AEN128" ></A ><P ><B >Example 2-8. SDL and OpenGL</B ></P ><PRE CLASS="PROGRAMLISTING" >/* * SDL OpenGL Tutorial. * (c) Michael Vance, 2000 * briareos@lokigames.com * * Distributed under terms of the LGPL. */ #include <SDL/SDL.h> #include <GL/gl.h> #include <GL/glu.h> #include <stdio.h> #include <stdlib.h> static GLboolean should_rotate = GL_TRUE; static void quit_tutorial( int code ) { /* * Quit SDL so we can release the fullscreen * mode and restore the previous video settings, * etc. */ SDL_Quit( ); /* Exit program. */ exit( code ); } static void handle_key_down( SDL_keysym* keysym ) { /* * We're only interested if 'Esc' has * been presssed. * * EXERCISE: * Handle the arrow keys and have that change the * viewing position/angle. */ switch( keysym->sym ) { case SDLK_ESCAPE: quit_tutorial( 0 ); break; case SDLK_SPACE: should_rotate = !should_rotate; break; default: break; } } static void process_events( void ) { /* Our SDL event placeholder. */ SDL_Event event; /* Grab all the events off the queue. */ while( SDL_PollEvent( &event ) ) { switch( event.type ) { case SDL_KEYDOWN: /* Handle key presses. */ handle_key_down( &event.key.keysym ); break; case SDL_QUIT: /* Handle quit requests (like Ctrl-c). */ quit_tutorial( 0 ); break; } } } static void draw_screen( void ) { /* Our angle of rotation. */ static float angle = 0.0f; /* * EXERCISE: * Replace this awful mess with vertex * arrays and a call to glDrawElements. * * EXERCISE: * After completing the above, change * it to use compiled vertex arrays. * * EXERCISE: * Verify my windings are correct here ;). */ static GLfloat v0[] = { -1.0f, -1.0f, 1.0f }; static GLfloat v1[] = { 1.0f, -1.0f, 1.0f }; static GLfloat v2[] = { 1.0f, 1.0f, 1.0f }; static GLfloat v3[] = { -1.0f, 1.0f, 1.0f }; static GLfloat v4[] = { -1.0f, -1.0f, -1.0f }; static GLfloat v5[] = { 1.0f, -1.0f, -1.0f }; static GLfloat v6[] = { 1.0f, 1.0f, -1.0f }; static GLfloat v7[] = { -1.0f, 1.0f, -1.0f }; static GLubyte red[] = { 255, 0, 0, 255 }; static GLubyte green[] = { 0, 255, 0, 255 }; static GLubyte blue[] = { 0, 0, 255, 255 }; static GLubyte white[] = { 255, 255, 255, 255 }; static GLubyte yellow[] = { 0, 255, 255, 255 }; static GLubyte black[] = { 0, 0, 0, 255 }; static GLubyte orange[] = { 255, 255, 0, 255 }; static GLubyte purple[] = { 255, 0, 255, 0 }; /* Clear the color and depth buffers. */ glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); /* We don't want to modify the projection matrix. */ glMatrixMode( GL_MODELVIEW ); glLoadIdentity( ); /* Move down the z-axis. */ glTranslatef( 0.0, 0.0, -5.0 ); /* Rotate. */ glRotatef( angle, 0.0, 1.0, 0.0 ); if( should_rotate ) { if( ++angle > 360.0f ) { angle = 0.0f; } } /* Send our triangle data to the pipeline. */ glBegin( GL_TRIANGLES ); glColor4ubv( red ); glVertex3fv( v0 ); glColor4ubv( green ); glVertex3fv( v1 ); glColor4ubv( blue ); glVertex3fv( v2 ); glColor4ubv( red ); glVertex3fv( v0 ); glColor4ubv( blue ); glVertex3fv( v2 ); glColor4ubv( white ); glVertex3fv( v3 ); glColor4ubv( green ); glVertex3fv( v1 ); glColor4ubv( black ); glVertex3fv( v5 ); glColor4ubv( orange ); glVertex3fv( v6 ); glColor4ubv( green ); glVertex3fv( v1 ); glColor4ubv( orange ); glVertex3fv( v6 ); glColor4ubv( blue ); glVertex3fv( v2 ); glColor4ubv( black ); glVertex3fv( v5 ); glColor4ubv( yellow ); glVertex3fv( v4 ); glColor4ubv( purple ); glVertex3fv( v7 ); glColor4ubv( black ); glVertex3fv( v5 ); glColor4ubv( purple ); glVertex3fv( v7 ); glColor4ubv( orange ); glVertex3fv( v6 ); glColor4ubv( yellow ); glVertex3fv( v4 ); glColor4ubv( red ); glVertex3fv( v0 ); glColor4ubv( white ); glVertex3fv( v3 ); glColor4ubv( yellow ); glVertex3fv( v4 ); glColor4ubv( white ); glVertex3fv( v3 ); glColor4ubv( purple ); glVertex3fv( v7 ); glColor4ubv( white ); glVertex3fv( v3 ); glColor4ubv( blue ); glVertex3fv( v2 ); glColor4ubv( orange ); glVertex3fv( v6 ); glColor4ubv( white ); glVertex3fv( v3 ); glColor4ubv( orange ); glVertex3fv( v6 ); glColor4ubv( purple ); glVertex3fv( v7 ); glColor4ubv( green ); glVertex3fv( v1 ); glColor4ubv( red ); glVertex3fv( v0 ); glColor4ubv( yellow ); glVertex3fv( v4 ); glColor4ubv( green ); glVertex3fv( v1 ); glColor4ubv( yellow ); glVertex3fv( v4 ); glColor4ubv( black ); glVertex3fv( v5 ); glEnd( ); /* * EXERCISE: * Draw text telling the user that 'Spc' * pauses the rotation and 'Esc' quits. * Do it using vetors and textured quads. */ /* * Swap the buffers. This this tells the driver to * render the next frame from the contents of the * back-buffer, and to set all rendering operations * to occur on what was the front-buffer. * * Double buffering prevents nasty visual tearing * from the application drawing on areas of the * screen that are being updated at the same time. */ SDL_GL_SwapBuffers( ); } static void setup_opengl( int width, int height ) { float ratio = (float) width / (float) height; /* Our shading model--Gouraud (smooth). */ glShadeModel( GL_SMOOTH ); /* Culling. */ glCullFace( GL_BACK ); glFrontFace( GL_CCW ); glEnable( GL_CULL_FACE ); /* Set the clear color. */ glClearColor( 0, 0, 0, 0 ); /* Setup our viewport. */ glViewport( 0, 0, width, height ); /* * Change to the projection matrix and set * our viewing volume. */ glMatrixMode( GL_PROJECTION ); glLoadIdentity( ); /* * EXERCISE: * Replace this with a call to glFrustum. */ gluPerspective( 60.0, ratio, 1.0, 1024.0 ); } int main( int argc, char* argv[] ) { /* Information about the current video settings. */ const SDL_VideoInfo* info = NULL; /* Dimensions of our window. */ int width = 0; int height = 0; /* Color depth in bits of our window. */ int bpp = 0; /* Flags we will pass into SDL_SetVideoMode. */ int flags = 0; /* First, initialize SDL's video subsystem. */ if( SDL_Init( SDL_INIT_VIDEO ) < 0 ) { /* Failed, exit. */ fprintf( stderr, "Video initialization failed: %s\n", SDL_GetError( ) ); quit_tutorial( 1 ); } /* Let's get some video information. */ info = SDL_GetVideoInfo( ); if( !info ) { /* This should probably never happen. */ fprintf( stderr, "Video query failed: %s\n", SDL_GetError( ) ); quit_tutorial( 1 ); } /* * Set our width/height to 640/480 (you would * of course let the user decide this in a normal * app). We get the bpp we will request from * the display. On X11, VidMode can't change * resolution, so this is probably being overly * safe. Under Win32, ChangeDisplaySettings * can change the bpp. */ width = 640; height = 480; bpp = info->vfmt->BitsPerPixel; /* * Now, we want to setup our requested * window attributes for our OpenGL window. * We want *at least* 5 bits of red, green * and blue. We also want at least a 16-bit * depth buffer. * * The last thing we do is request a double * buffered window. '1' turns on double * buffering, '0' turns it off. * * Note that we do not use SDL_DOUBLEBUF in * the flags to SDL_SetVideoMode. That does * not affect the GL attribute state, only * the standard 2D blitting setup. */ SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 ); SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 ); SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 ); /* * We want to request that SDL provide us * with an OpenGL window, in a fullscreen * video mode. * * EXERCISE: * Make starting windowed an option, and * handle the resize events properly with * glViewport. */ flags = SDL_OPENGL | SDL_FULLSCREEN; /* * Set the video mode */ if( SDL_SetVideoMode( width, height, bpp, flags ) == 0 ) { /* * This could happen for a variety of reasons, * including DISPLAY not being set, the specified * resolution not being available, etc. */ fprintf( stderr, "Video mode set failed: %s\n", SDL_GetError( ) ); quit_tutorial( 1 ); } /* * At this point, we should have a properly setup * double-buffered window for use with OpenGL. */ setup_opengl( width, height ); /* * Now we want to begin our normal app process-- * an event loop with a lot of redrawing. */ while( 1 ) { /* Process incoming events. */ process_events( ); /* Draw the screen. */ draw_screen( ); } /* * EXERCISE: * Record timings using SDL_GetTicks() and * and print out frames per second at program * end. */ /* Never reached. */ return 0; }</PRE ></DIV ></DIV ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="guidevideo.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="guideinput.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Graphics and Video</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="guidevideo.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Input handling</TD ></TR ></TABLE ></DIV ></BODY ></HTML >