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lxdream.org :: lxdream/src/drivers/gl_fbo.c
lxdream 0.9.1
released Jun 29
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filename src/drivers/gl_fbo.c
changeset 1298:d0eb2307b847
prev1251:b8ab59d39756
author nkeynes
date Wed Feb 04 08:38:23 2015 +1000 (5 years ago)
permissions -rw-r--r--
last change Fix assorted compile warnings reported by Clang
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     1 /**
     2  * $Id$
     3  *
     4  * GL framebuffer-based driver shell. This requires the EXT_framebuffer_object
     5  * extension, but is much nicer/faster/etc than pbuffers when it's available.
     6  * This is (optionally) used indirectly by the top-level GLX driver.
     7  *
     8  * Strategy-wise, we maintain 2 framebuffers with up to 4 target colour
     9  * buffers a piece. Effectively this reserves one fb for display output,
    10  * and the other for texture output (each fb has a single size).
    11  *
    12  * Copyright (c) 2005 Nathan Keynes.
    13  *
    14  * This program is free software; you can redistribute it and/or modify
    15  * it under the terms of the GNU General Public License as published by
    16  * the Free Software Foundation; either version 2 of the License, or
    17  * (at your option) any later version.
    18  *
    19  * This program is distributed in the hope that it will be useful,
    20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    22  * GNU General Public License for more details.
    23  */
    25 #define GL_GLEXT_PROTOTYPES 1
    27 #include <stdlib.h>
    28 #include "lxdream.h"
    29 #include "display.h"
    30 #include "drivers/video_gl.h"
    31 #include "pvr2/glutil.h"
    33 #if defined(HAVE_OPENGL_FBO) || defined(HAVE_OPENGL_FBO_EXT)
    35 #define MAX_FRAMEBUFFERS 2
    36 #define MAX_TEXTURES_PER_FB 16
    38 static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height, GLuint tex_id );
    39 static void gl_fbo_destroy_render_buffer( render_buffer_t buffer );
    40 static gboolean gl_fbo_set_render_target( render_buffer_t buffer );
    41 static void gl_fbo_finish_render( render_buffer_t buffer );
    42 static void gl_fbo_display_render_buffer( render_buffer_t buffer );
    43 static void gl_fbo_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer );
    44 static void gl_fbo_display_blank( uint32_t colour );
    45 static gboolean gl_fbo_test_framebuffer( );
    46 static gboolean gl_fbo_read_render_buffer( unsigned char *target, render_buffer_t buffer, int rowstride, int format );
    48 extern uint32_t video_width, video_height;
    50 /**
    51  * Framebuffer info structure
    52  */
    53 struct gl_fbo_info {
    54     GLuint fb_id;
    55     GLuint depth_id;
    56     GLuint stencil_id;
    57     GLuint tex_ids[MAX_TEXTURES_PER_FB];
    58     int width, height;
    59 };
    61 static GLint gl_fbo_max_attachments = 0;
    62 static GLint gl_fbo_depth_component;
    63 static gboolean gl_fbo_have_packed_stencil = FALSE;
    64 static struct gl_fbo_info fbo[MAX_FRAMEBUFFERS];
    66 #define ATTACHMENT_POINT(n) (GL_COLOR_ATTACHMENT0+(n))
    67 static int last_used_fbo;
    69 gboolean gl_fbo_is_supported()
    70 {
    71     return isGLExtensionSupported("GL_EXT_framebuffer_object") || isOpenGLES2();
    72 }
    74 /**
    75  * Construct the initial frame buffers and allocate ids for everything.
    76  * The render handling driver methods are set to the fbo versions.
    77  */
    78 void gl_fbo_init( display_driver_t driver ) 
    79 {
    80     int i,j;
    81     GLuint fbids[MAX_FRAMEBUFFERS];
    82     GLuint rbids[MAX_FRAMEBUFFERS*2]; /* depth buffer, stencil buffer per fb */
    84     gl_fbo_max_attachments = glGetMaxColourAttachments();
    85     glGenFramebuffers( MAX_FRAMEBUFFERS, &fbids[0] );
    86     glGenRenderbuffers( MAX_FRAMEBUFFERS*2, &rbids[0] );
    87     for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
    88         fbo[i].fb_id = fbids[i];
    89         fbo[i].depth_id = rbids[i*2];
    90         fbo[i].stencil_id = rbids[i*2+1];
    91         fbo[i].width = -1;
    92         fbo[i].height = -1;
    93         for( j=0; j<MAX_TEXTURES_PER_FB; j++ ) {
    94             fbo[i].tex_ids[j] = -1;
    95         }
    96     }
    97     last_used_fbo = 0;
    99     if( isGLExtensionSupported("GL_EXT_packed_depth_stencil" ) ) {
   100         driver->capabilities.stencil_bits = 8;
   101         gl_fbo_have_packed_stencil = TRUE;
   102     } else {
   103         driver->capabilities.stencil_bits = 0;
   104         gl_fbo_have_packed_stencil = FALSE;
   105         WARN( "Packed depth stencil not available - disabling shadow volumes" );
   106     }
   107     if( driver->capabilities.depth_bits >= 24 ) {
   108         gl_fbo_depth_component = GL_DEPTH_COMPONENT24;
   109     } else {
   110         gl_fbo_depth_component = GL_DEPTH_COMPONENT16;
   111     }
   113     driver->create_render_buffer = gl_fbo_create_render_buffer;
   114     driver->destroy_render_buffer = gl_fbo_destroy_render_buffer;
   115     driver->set_render_target = gl_fbo_set_render_target;
   116     driver->finish_render = gl_fbo_finish_render;
   117     driver->display_render_buffer = gl_fbo_display_render_buffer;
   118     driver->load_frame_buffer = gl_fbo_load_frame_buffer;
   119     driver->display_blank = gl_fbo_display_blank;
   120     driver->read_render_buffer = gl_fbo_read_render_buffer;
   122     gl_fbo_test_framebuffer();
   123     glBindFramebuffer(GL_FRAMEBUFFER, 0);
   124 }
   126 void gl_fbo_shutdown()
   127 {
   128     int i;
   129     glBindFramebuffer( GL_FRAMEBUFFER, 0 );
   130     for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
   131         glDeleteFramebuffers( 1, &fbo[i].fb_id );
   132         glDeleteRenderbuffers( 2, &fbo[i].depth_id );
   133     }
   134 }
   136 static void gl_fbo_setup_framebuffer( int bufno, int width, int height )
   137 {
   138     int i;
   139     glBindFramebuffer(GL_FRAMEBUFFER, fbo[bufno].fb_id);
   141     /* Clear out any existing texture attachments */
   142     for( i=0; i<gl_fbo_max_attachments; i++ ) {
   143         if( fbo[bufno].tex_ids[i] != -1 ) {
   144             glFramebufferTexture2D(GL_FRAMEBUFFER, ATTACHMENT_POINT(i),
   145                     GL_TEXTURE_2D, 0, 0);
   146             fbo[bufno].tex_ids[i] = -1;
   147         }
   148     }
   150     /* Setup the renderbuffers */
   151     if( gl_fbo_have_packed_stencil ) {
   152         glBindRenderbuffer(GL_RENDERBUFFER, fbo[bufno].depth_id);
   153         glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8, width, height);
   154         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
   155                                      GL_RENDERBUFFER, fbo[bufno].depth_id);
   156         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT,
   157                                      GL_RENDERBUFFER, fbo[bufno].depth_id);
   158     } else {
   159         glBindRenderbuffer(GL_RENDERBUFFER, fbo[bufno].depth_id);
   160         glRenderbufferStorage(GL_RENDERBUFFER, gl_fbo_depth_component, width, height);
   161         glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT,
   162                                      GL_RENDERBUFFER, fbo[bufno].depth_id);
   163         /* In theory you could attach a separate stencil buffer. In practice this 
   164          * isn't actually supported by any hardware I've had access to, so we're
   165          * stencil-less.
   166          */
   167     }
   168     fbo[bufno].width = width;
   169     fbo[bufno].height = height;
   170 }
   172 static int gl_fbo_get_framebuffer( int width, int height ) 
   173 {
   174     int bufno = -1, i;
   175     /* find a compatible framebuffer context */
   176     for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
   177         if( fbo[i].width == -1 && bufno == -1 ) {
   178             bufno = i;
   179         } else if( fbo[i].width == width && fbo[i].height == height ) {
   180             bufno = i;
   181             break;
   182         }
   183     }
   184     if( bufno == -1 ) {
   185         bufno = last_used_fbo + 1;
   186         if( bufno >= MAX_FRAMEBUFFERS ) {
   187             bufno = 0;
   188         }
   189         last_used_fbo = bufno;
   190     }
   191     if( fbo[bufno].width == width && fbo[bufno].height == height ) {
   192         glBindFramebuffer( GL_FRAMEBUFFER, fbo[bufno].fb_id );
   193     } else {
   194         gl_fbo_setup_framebuffer( bufno, width, height );
   195     } 
   196     return bufno;
   197 }
   199 /**
   200  * Attach a texture to the framebuffer. The texture must already be initialized
   201  * to the correct dimensions etc.
   202  */
   203 static GLint gl_fbo_attach_texture( int fbo_no, GLint tex_id ) {
   204     int attach = -1, i;
   205     for( i=0; i<gl_fbo_max_attachments; i++ ) {
   206         if( fbo[fbo_no].tex_ids[i] == tex_id ) {
   207 #ifdef HAVE_OPENGL_DRAW_BUFFER
   208             glDrawBuffer(ATTACHMENT_POINT(i));
   209             glReadBuffer(ATTACHMENT_POINT(i)); 
   210 #endif
   211             return ATTACHMENT_POINT(i); // already attached
   212         } else if( fbo[fbo_no].tex_ids[i] == -1 && attach == -1 ) {
   213             attach = i;
   214         }
   215     }
   216     if( attach == -1 ) {
   217         attach = 0;
   218     }
   219     fbo[fbo_no].tex_ids[attach] = tex_id;
   220     glBindTexture( GL_TEXTURE_2D, 0 ); // Ensure the output texture is unbound
   221     glFramebufferTexture2D(GL_FRAMEBUFFER, ATTACHMENT_POINT(attach), 
   222                               GL_TEXTURE_2D, tex_id, 0 );
   223     /* Set draw/read buffers by default */
   224 #ifdef HAVE_OPENGL_DRAW_BUFFER    
   225     glDrawBuffer(ATTACHMENT_POINT(attach));
   226     glReadBuffer(ATTACHMENT_POINT(attach)); 
   227 #endif
   229     return ATTACHMENT_POINT(attach);
   230 }
   232 static gboolean gl_fbo_test_framebuffer( )
   233 {
   234     gboolean result = TRUE;
   235     glGetError(); /* Clear error state just in case */
   236     render_buffer_t buffer = gl_fbo_create_render_buffer( 640, 480, 0 );
   237     gl_fbo_set_render_target(buffer);
   239     GLint status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
   240     if( status != GL_FRAMEBUFFER_COMPLETE ) {
   241         ERROR( "Framebuffer failure: %x", status );
   242         result = FALSE;
   243     }
   244     if( result ) {
   245         result = gl_check_error( "Setting up framebuffer" );
   246     }
   248     gl_fbo_destroy_render_buffer( buffer );
   249     return result;
   250 }
   252 static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height, GLuint tex_id )
   253 {
   254     render_buffer_t buffer = calloc( sizeof(struct render_buffer), 1 );
   255     buffer->width = width;
   256     buffer->height = height;
   257     buffer->tex_id = tex_id;
   258     if( tex_id == 0 ) {
   259         GLuint tex;
   260         glGenTextures( 1, &tex );
   261         buffer->buf_id = tex;
   262     } else {
   263         buffer->buf_id = tex_id;
   264         glBindTexture( GL_TEXTURE_2D, tex_id );
   265     }
   266     glBindTexture( GL_TEXTURE_2D, buffer->buf_id );
   267     glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );
   268     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
   269     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
   270     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
   271     glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
   272     return buffer;
   273 }
   275 /**
   276  * Ensure the texture in the given render buffer is not attached to a 
   277  * framebuffer (ie, so we can safely use it as a texture during the rendering
   278  * cycle, or before deletion).
   279  */
   280 static void gl_fbo_detach_render_buffer( render_buffer_t buffer )
   281 {
   282     int i,j;
   283     for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
   284         if( fbo[i].width == buffer->width && fbo[i].height == buffer->height ) {
   285             for( j=0; j<gl_fbo_max_attachments; j++ ) {
   286                 if( fbo[i].tex_ids[j] == buffer->buf_id ) {
   287                     glBindFramebuffer(GL_FRAMEBUFFER, fbo[i].fb_id);
   288                     glFramebufferTexture2D(GL_FRAMEBUFFER, ATTACHMENT_POINT(j), 
   289                                               GL_TEXTURE_2D, GL_NONE, 0 );
   290                     fbo[i].tex_ids[j] = -1;
   291                     return;
   292                 }                    
   293             }
   294             break;
   295         }
   296     }
   297 }
   299 static void gl_fbo_destroy_render_buffer( render_buffer_t buffer )
   300 {
   301     gl_fbo_detach_render_buffer( buffer );
   303     if( buffer->buf_id != buffer->tex_id ) {
   304         // If tex_id was set at buffer creation, we don't own the texture.
   305         // Otherwise, delete it now.
   306         GLuint tex = buffer->buf_id; 
   307         glDeleteTextures( 1, &tex );
   308     }
   309     buffer->buf_id = 0;
   310     buffer->tex_id = 0;
   311     free( buffer );
   312 }
   314 static gboolean gl_fbo_set_render_target( render_buffer_t buffer )
   315 {
   316     int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
   317     gl_fbo_attach_texture( fb, buffer->buf_id );
   318     /* setup the gl context */
   319     glViewport( 0, 0, buffer->width, buffer->height );
   321     return TRUE;
   322 }
   324 static void gl_fbo_finish_render( render_buffer_t buffer )
   325 {
   326     glFinish();
   327     gl_fbo_detach_render_buffer(buffer);
   328 }
   330 /**
   331  * Render the texture holding the given buffer to the front window
   332  * buffer.
   333  */
   334 static void gl_fbo_display_render_buffer( render_buffer_t buffer )
   335 {
   336     gl_fbo_detach();
   337     gl_display_render_buffer( buffer );
   338     if( display_driver->swap_buffers )
   339         display_driver->swap_buffers();
   340 }
   342 static void gl_fbo_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer )
   343 {
   344     gl_fbo_detach();
   345     gl_frame_buffer_to_tex( frame, buffer->buf_id );
   346 }
   348 static void gl_fbo_display_blank( uint32_t colour )
   349 {
   350     gl_fbo_detach();
   351     gl_display_blank( colour );
   352     if( display_driver->swap_buffers )
   353         display_driver->swap_buffers();
   354 }
   356 void gl_fbo_detach()
   357 {
   358     glBindFramebuffer( GL_FRAMEBUFFER, 0 );
   359     /* Make sure texture attachment is not a current draw/read buffer */
   360 #ifdef HAVE_OPENGL_DRAW_BUFFER
   361     glDrawBuffer( GL_FRONT );
   362     glReadBuffer( GL_FRONT );
   363 #endif
   364 }    
   366 static gboolean gl_fbo_read_render_buffer( unsigned char *target, render_buffer_t buffer, 
   367                                            int rowstride, int format )
   368 {
   369     int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
   370     gl_fbo_attach_texture( fb, buffer->buf_id );
   371     return gl_read_render_buffer( target, buffer, rowstride, format );
   372 }
   374 #else
   375 gboolean gl_fbo_is_supported()
   376 {
   377     return FALSE;
   378 }
   380 void gl_fbo_init( display_driver_t driver ) 
   381 {
   382 }
   384 #endif
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