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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 863:a5e5310061e2
prev857:3d8944884eaa
next868:c5b4ed31d819
author nkeynes
date Sun Sep 28 01:09:51 2008 +0000 (14 years ago)
permissions -rw-r--r--
last change Initial shadow volume implementation for opaque polygons (stencil isn't quite
right, but we get some kind of shadows now)
file annotate diff log raw
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/**
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 * $Id$
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 *
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 * GL framebuffer-based driver shell. This requires the EXT_framebuffer_object
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 * extension, but is much nicer/faster/etc than pbuffers when it's available.
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 * This is (optionally) used indirectly by the top-level GLX driver.
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 *
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 * Strategy-wise, we maintain 2 framebuffers with up to 4 target colour
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 * buffers a piece. Effectively this reserves one fb for display output,
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 * and the other for texture output (each fb has a single size).
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 *
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 * Copyright (c) 2005 Nathan Keynes.
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 */
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#define GL_GLEXT_PROTOTYPES 1
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#include <stdlib.h>
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#include "lxdream.h"
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#include "display.h"
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#include "drivers/video_gl.h"
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#include "pvr2/glutil.h"
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#ifdef HAVE_OPENGL_FBO
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#define MAX_FRAMEBUFFERS 2
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#define MAX_TEXTURES_PER_FB 16
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static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height, GLuint tex_id );
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static void gl_fbo_destroy_render_buffer( render_buffer_t buffer );
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static gboolean gl_fbo_set_render_target( render_buffer_t buffer );
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static void gl_fbo_finish_render( render_buffer_t buffer );
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static void gl_fbo_display_render_buffer( render_buffer_t buffer );
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static void gl_fbo_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer );
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static void gl_fbo_display_blank( uint32_t colour );
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static gboolean gl_fbo_read_render_buffer( unsigned char *target, render_buffer_t buffer, int rowstride, int format );
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extern uint32_t video_width, video_height;
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/**
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 * Framebuffer info structure
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 */
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struct gl_fbo_info {
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    GLuint fb_id;
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    GLuint depth_id;
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    GLuint stencil_id;
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    GLuint tex_ids[MAX_TEXTURES_PER_FB];
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    int width, height;
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};
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static GLint gl_fbo_max_attachments = 0;
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static gboolean gl_fbo_have_packed_stencil = FALSE;
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static struct gl_fbo_info fbo[MAX_FRAMEBUFFERS];
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#define ATTACHMENT_POINT(n) (GL_COLOR_ATTACHMENT0_EXT+(n))
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static int last_used_fbo;
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gboolean gl_fbo_is_supported()
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{
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    return isGLExtensionSupported("GL_EXT_framebuffer_object");
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}
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/**
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 * Construct the initial frame buffers and allocate ids for everything.
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 * The render handling driver methods are set to the fbo versions.
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 */
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void gl_fbo_init( display_driver_t driver ) 
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{
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    int i,j;
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    GLuint fbids[MAX_FRAMEBUFFERS];
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    GLuint rbids[MAX_FRAMEBUFFERS*2]; /* depth buffer, stencil buffer per fb */
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    glGetIntegerv(GL_MAX_COLOR_ATTACHMENTS_EXT, &gl_fbo_max_attachments);
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    glGenFramebuffersEXT( MAX_FRAMEBUFFERS, &fbids[0] );
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    glGenRenderbuffersEXT( MAX_FRAMEBUFFERS*2, &rbids[0] );
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    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
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        fbo[i].fb_id = fbids[i];
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        fbo[i].depth_id = rbids[i*2];
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        fbo[i].stencil_id = rbids[i*2+1];
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        fbo[i].width = -1;
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        fbo[i].height = -1;
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        for( j=0; j<MAX_TEXTURES_PER_FB; j++ ) {
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            fbo[i].tex_ids[j] = -1;
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        }
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    }
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    last_used_fbo = 0;
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    if( isGLExtensionSupported("GL_EXT_packed_depth_stencil" ) ) {
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        driver->capabilities.stencil_bits = 8;
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        gl_fbo_have_packed_stencil = TRUE;
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    } else {
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        driver->capabilities.stencil_bits = 0;
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        gl_fbo_have_packed_stencil = FALSE;
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        WARN( "Packed depth stencil not available - disabling shadow volumes" );
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    }
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    driver->create_render_buffer = gl_fbo_create_render_buffer;
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    driver->destroy_render_buffer = gl_fbo_destroy_render_buffer;
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    driver->set_render_target = gl_fbo_set_render_target;
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    driver->finish_render = gl_fbo_finish_render;
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    driver->display_render_buffer = gl_fbo_display_render_buffer;
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    driver->load_frame_buffer = gl_fbo_load_frame_buffer;
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    driver->display_blank = gl_fbo_display_blank;
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    driver->read_render_buffer = gl_fbo_read_render_buffer;
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    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
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    glDrawBuffer(GL_FRONT);
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    glReadBuffer(GL_FRONT);
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}
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void gl_fbo_shutdown()
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{
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    int i;
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    glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
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    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
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        glDeleteFramebuffersEXT( 1, &fbo[i].fb_id );
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        glDeleteRenderbuffersEXT( 2, &fbo[i].depth_id );
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    }
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}
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static void gl_fbo_setup_framebuffer( int bufno, int width, int height )
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{
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    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo[bufno].fb_id);
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    if( gl_fbo_have_packed_stencil ) {
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        glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
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        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH24_STENCIL8_EXT, width, height);
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        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
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                                     GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
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        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
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                                     GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
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    } else {
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        glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
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        glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24, width, height);
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        glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
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                                     GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
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        /* In theory you could attach a separate stencil buffer. In practice this 
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         * isn't actually supported by any hardware I've had access to, so we're
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         * stencil-less.
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         */
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    }
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    fbo[bufno].width = width;
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    fbo[bufno].height = height;
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}
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static int gl_fbo_get_framebuffer( int width, int height ) 
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{
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    int bufno = -1, i;
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    /* find a compatible framebuffer context */
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    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
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        if( fbo[i].width == -1 && bufno == -1 ) {
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            bufno = i;
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        } else if( fbo[i].width == width && fbo[i].height == height ) {
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            bufno = i;
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            break;
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        }
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    }
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    if( bufno == -1 ) {
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        bufno = last_used_fbo + 1;
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        if( bufno > MAX_FRAMEBUFFERS ) {
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            bufno = 0;
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        }
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        last_used_fbo = bufno;
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    }
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    if( fbo[bufno].width == width && fbo[bufno].height == height ) {
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        glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fbo[bufno].fb_id );
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    } else {
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        gl_fbo_setup_framebuffer( bufno, width, height );
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    } 
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    return bufno;
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}
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/**
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 * Attach a texture to the framebuffer. The texture must already be initialized
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 * to the correct dimensions etc.
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 */
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static GLint gl_fbo_attach_texture( int fbo_no, GLint tex_id ) {
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    int attach = -1, i;
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    for( i=0; i<gl_fbo_max_attachments; i++ ) {
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        if( fbo[fbo_no].tex_ids[i] == tex_id ) {
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            glDrawBuffer(ATTACHMENT_POINT(i));
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            glReadBuffer(ATTACHMENT_POINT(i)); 
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            return ATTACHMENT_POINT(i); // already attached
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        } else if( fbo[fbo_no].tex_ids[i] == -1 && attach == -1 ) {
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            attach = i;
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        }
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    }
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    if( attach == -1 ) {
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        attach = 0;
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    }
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    fbo[fbo_no].tex_ids[attach] = tex_id;
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    glBindTexture( GL_TEXTURE_RECTANGLE_ARB, 0 ); // Ensure the output texture is unbound
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    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, ATTACHMENT_POINT(attach), 
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                              GL_TEXTURE_RECTANGLE_ARB, tex_id, 0 );
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    /* Set draw/read buffers by default */
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    glDrawBuffer(ATTACHMENT_POINT(attach));
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    glReadBuffer(ATTACHMENT_POINT(attach)); 
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    GLint status = glGetError();
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    if( status != GL_NO_ERROR ) {
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        ERROR( "GL error setting render target (%x)!", status );
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    }
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    status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
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    if( status != GL_FRAMEBUFFER_COMPLETE_EXT ) {
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        ERROR( "Framebuffer failure: %x", status );
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        exit(1);
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    }
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    return ATTACHMENT_POINT(attach);
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}
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static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height, GLuint tex_id )
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{
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    render_buffer_t buffer = calloc( sizeof(struct render_buffer), 1 );
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    buffer->width = width;
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    buffer->height = height;
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    buffer->tex_id = tex_id;
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    if( tex_id == 0 ) {
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        GLuint tex;
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        glGenTextures( 1, &tex );
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        buffer->buf_id = tex;
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        glBindTexture( GL_TEXTURE_RECTANGLE_ARB, tex );
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        glTexImage2D( GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );
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    } else {
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        buffer->buf_id = tex_id;
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        glBindTexture( GL_TEXTURE_RECTANGLE_ARB, tex_id );
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    }
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    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP );
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    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP );
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    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
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    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
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    return buffer;
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}
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/**
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 * Ensure the texture in the given render buffer is not attached to a 
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 * framebuffer (ie, so we can safely use it as a texture during the rendering
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 * cycle, or before deletion).
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 */
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static void gl_fbo_detach_render_buffer( render_buffer_t buffer )
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{
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    int i,j;
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    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
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        if( fbo[i].width == buffer->width && fbo[i].height == buffer->height ) {
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            for( j=0; j<gl_fbo_max_attachments; j++ ) {
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                if( fbo[i].tex_ids[j] == buffer->buf_id ) {
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                    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo[i].fb_id);
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                    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, ATTACHMENT_POINT(j), 
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                                              GL_TEXTURE_RECTANGLE_ARB, GL_NONE, 0 );
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                    fbo[i].tex_ids[j] = -1;
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                    return;
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                }                    
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            }
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            break;
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        }
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    }
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}
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static void gl_fbo_destroy_render_buffer( render_buffer_t buffer )
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{
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    int i,j;
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   272
    gl_fbo_detach_render_buffer( buffer );
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    if( buffer->buf_id != buffer->tex_id ) {
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        // If tex_id was set at buffer creation, we don't own the texture.
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        // Otherwise, delete it now.
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        GLuint tex = buffer->buf_id; 
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        glDeleteTextures( 1, &tex );
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    }
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    buffer->buf_id = 0;
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    buffer->tex_id = 0;
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    free( buffer );
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}
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static gboolean gl_fbo_set_render_target( render_buffer_t buffer )
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{
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   287
    glFinish();
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    glGetError();
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    int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
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    gl_fbo_attach_texture( fb, buffer->buf_id );
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    /* setup the gl context */
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    glViewport( 0, 0, buffer->width, buffer->height );
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    return TRUE;
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}
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   296
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   297
static void gl_fbo_finish_render( render_buffer_t buffer )
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{
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   299
    glFinish();
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   300
    glGetError();
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   301
    gl_fbo_detach_render_buffer(buffer);
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   302
}
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   303
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/**
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 * Render the texture holding the given buffer to the front window
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 * buffer.
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 */
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static void gl_fbo_display_render_buffer( render_buffer_t buffer )
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   309
{
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    glFinish();
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    gl_fbo_detach();
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   312
    gl_display_render_buffer( buffer );
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   313
}
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   314
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   315
static void gl_fbo_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer )
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   316
{
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   317
    glFinish();
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   318
    gl_fbo_detach();
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   319
    gl_load_frame_buffer( frame, buffer->buf_id );
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   320
}
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   321
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static void gl_fbo_display_blank( uint32_t colour )
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   323
{
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   324
    glFinish();
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   325
    gl_fbo_detach();
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    gl_display_blank( colour );
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   327
}
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   328
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   329
void gl_fbo_detach()
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   330
{
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   331
    glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
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   332
    glDrawBuffer( GL_FRONT );
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   333
    glReadBuffer( GL_FRONT );
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   334
}    
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   335
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   336
static gboolean gl_fbo_read_render_buffer( unsigned char *target, render_buffer_t buffer, 
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   337
                                           int rowstride, int format )
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   338
{
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   339
    glGetError();
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   340
    int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
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    gl_fbo_attach_texture( fb, buffer->buf_id );
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    return gl_read_render_buffer( target, buffer, rowstride, format );
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}
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#else
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gboolean gl_fbo_is_supported()
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{
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    return FALSE;
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}
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void gl_fbo_init( display_driver_t driver ) 
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{
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}
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#endif
.