--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/drivers/gl_fbo.c	Sun Feb 11 10:09:32 2007 +0000
@@ -0,0 +1,299 @@
+/**
+ * $Id: gl_fbo.c,v 1.1 2007-02-11 10:09:32 nkeynes Exp $
+ *
+ * GL framebuffer-based driver shell. This requires the EXT_framebuffer_object
+ * extension, but is much nicer/faster/etc than pbuffers when it's available.
+ * This is (optionally) used indirectly by the top-level GLX driver.
+ *
+ * Strategy-wise, we maintain 2 framebuffers with up to 4 target colour
+ * buffers a piece. Effectively this reserves one fb for display output,
+ * and the other for texture output (each fb has a single size).
+ *
+ * Copyright (c) 2005 Nathan Keynes.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <GL/gl.h>
+#include "display.h"
+
+#define MAX_FRAMEBUFFERS 2
+#define MAX_TEXTURES_PER_FB 4
+
+static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height );
+static void gl_fbo_destroy_render_buffer( render_buffer_t buffer );
+static gboolean gl_fbo_set_render_target( render_buffer_t buffer );
+static gboolean gl_fbo_display_render_buffer( render_buffer_t buffer );
+static gboolean gl_fbo_display_frame_buffer( frame_buffer_t buffer );
+static gboolean gl_fbo_display_blank( uint32_t colour );
+static gboolean gl_fbo_read_render_buffer( render_buffer_t buffer, char *target );
+
+extern uint32_t video_width, video_height;
+
+/**
+ * Framebuffer info structure
+ */
+struct gl_fbo_info {
+    GLuint fb_id;
+    GLuint depth_id;
+    GLuint stencil_id;
+    GLuint tex_ids[MAX_TEXTURES_PER_FB];
+    int width, height;
+};
+
+static struct gl_fbo_info fbo[MAX_FRAMEBUFFERS];
+const static int ATTACHMENT_POINTS[MAX_TEXTURES_PER_FB] = {
+    GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT, 
+    GL_COLOR_ATTACHMENT2_EXT, GL_COLOR_ATTACHMENT3_EXT };
+static int last_used_fbo;
+
+gboolean gl_fbo_is_supported()
+{
+    return isGLExtensionSupported("GL_EXT_framebuffer_object");
+}
+
+/**
+ * Construct the initial frame buffers and allocate ids for everything.
+ * The render handling driver methods are set to the fbo versions.
+ */
+void gl_fbo_init( display_driver_t driver ) 
+{
+    int i,j;
+    int fbids[MAX_FRAMEBUFFERS];
+    int rbids[MAX_FRAMEBUFFERS*2]; /* depth buffer, stencil buffer per fb */
+    
+    glGenFramebuffersEXT( MAX_FRAMEBUFFERS, &fbids );
+    glGenRenderbuffersEXT( MAX_FRAMEBUFFERS*2, &rbids );
+    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
+	fbo[i].fb_id = fbids[i];
+	fbo[i].depth_id = rbids[i*2];
+	fbo[i].stencil_id = rbids[i*2+1];
+	fbo[i].width = -1;
+	fbo[i].height = -1;
+	for( j=0; j<MAX_TEXTURES_PER_FB; j++ ) {
+	    fbo[i].tex_ids[j] = -1;
+	}
+    }
+    last_used_fbo = 0;
+
+    driver->create_render_buffer = gl_fbo_create_render_buffer;
+    driver->destroy_render_buffer = gl_fbo_destroy_render_buffer;
+    driver->set_render_target = gl_fbo_set_render_target;
+    driver->display_render_buffer = gl_fbo_display_render_buffer;
+    driver->display_frame_buffer = gl_fbo_display_frame_buffer;
+    driver->display_blank = gl_fbo_display_blank;
+    driver->read_render_buffer = gl_fbo_read_render_buffer;
+}
+
+void gl_fbo_shutdown()
+{
+    int i;
+    glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
+    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
+	glDeleteFramebuffersEXT( 1, &fbo[i].fb_id );
+	glDeleteRenderbuffersEXT( 2, &fbo[i].depth_id );
+    }
+}
+
+void gl_fbo_setup_framebuffer( int bufno, int width, int height )
+{
+    glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo[bufno].fb_id);
+    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
+    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24, width, height);
+    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
+				 GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
+    /* Stencil doesn't work on ATI, and we're not using it at the moment anyway, so...
+    glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo[bufno].stencil_id);
+    glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_STENCIL_INDEX, width, height);
+    glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
+				 GL_RENDERBUFFER_EXT, fbo[bufno].stencil_id);
+    */
+    fbo[bufno].width = width;
+    fbo[bufno].height = height;
+}
+
+int gl_fbo_get_framebuffer( int width, int height ) 
+{
+    int bufno = -1, i;
+    /* find a compatible framebuffer context */
+    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
+	if( fbo[i].width == -1 && bufno == -1 ) {
+	    bufno = i;
+	} else if( fbo[i].width == width && fbo[i].height == height ) {
+	    bufno = i;
+	    break;
+	}
+    }
+    if( bufno == -1 ) {
+	bufno = last_used_fbo + 1;
+	if( bufno > MAX_FRAMEBUFFERS ) {
+	    bufno = 0;
+	}
+	last_used_fbo = bufno;
+    }
+    if( fbo[bufno].width == width && fbo[bufno].height == height ) {
+	glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fbo[bufno].fb_id );
+    } else {
+	gl_fbo_setup_framebuffer( bufno, width, height );
+    } 
+    return bufno;
+}
+
+/**
+ * Attach a texture to the framebuffer. The texture must already be initialized
+ * to the correct dimensions etc.
+ */
+static GLint gl_fbo_attach_texture( int fbo_no, GLint tex_id ) {
+    int attach = -1, i;
+    for( i=0; i<MAX_TEXTURES_PER_FB; i++ ) {
+	if( fbo[fbo_no].tex_ids[i] == tex_id ) {
+	    glDrawBuffer(ATTACHMENT_POINTS[i]);
+	    glReadBuffer(ATTACHMENT_POINTS[i]); 
+	    return ATTACHMENT_POINTS[i]; // already attached
+	} else if( fbo[fbo_no].tex_ids[i] == -1 && attach == -1 ) {
+	    attach = i;
+	}
+    }
+    if( attach == -1 ) {
+	/* should never happen */
+	attach = 0;
+    }
+    fbo[fbo_no].tex_ids[attach] = tex_id;
+    glBindTexture( GL_TEXTURE_RECTANGLE_ARB, 0 ); // Ensure the output texture is unbound
+    glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, ATTACHMENT_POINTS[attach], 
+			      GL_TEXTURE_RECTANGLE_ARB, tex_id, 0 );
+    /* Set draw/read buffers by default */
+    glDrawBuffer(ATTACHMENT_POINTS[attach]);
+    glReadBuffer(ATTACHMENT_POINTS[attach]); 
+
+
+    GLint status = glGetError();
+    if( status != GL_NO_ERROR ) {
+	ERROR( "GL error setting render target (%x)!", status );
+    }
+    status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
+    if( status != GL_FRAMEBUFFER_COMPLETE_EXT ) {
+	ERROR( "Framebuffer failure: %x", status );
+	exit(1);
+    }
+
+    return ATTACHMENT_POINTS[attach];
+}
+
+static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height )
+{
+    render_buffer_t buffer = calloc( sizeof(struct render_buffer), 1 );
+    buffer->width = width;
+    buffer->height = height;
+    glGenTextures( 1, &buffer->buf_id );
+    glBindTexture( GL_TEXTURE_RECTANGLE_ARB, buffer->buf_id );
+    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP );
+    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP );
+    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
+    glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
+    glTexImage2D( GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );
+    return buffer;
+}
+
+static void gl_fbo_destroy_render_buffer( render_buffer_t buffer )
+{
+    int i,j;
+    for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
+	for( j=0; j < MAX_TEXTURES_PER_FB; j++ ) {
+	    if( fbo[i].tex_ids[j] == buffer->buf_id ) {
+		glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, ATTACHMENT_POINTS[j], 
+					  GL_TEXTURE_RECTANGLE_ARB, GL_NONE, 0 );
+		fbo[i].tex_ids[j] = -1;
+	    }
+	}
+    }
+    
+    glDeleteTextures( 1, &buffer->buf_id );
+    buffer->buf_id = 0;
+    free( buffer );
+}
+
+static gboolean gl_fbo_set_render_target( render_buffer_t buffer )
+{
+    glGetError();
+    int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
+    GLint attach = gl_fbo_attach_texture( fb, buffer->buf_id );
+    /* setup the gl context */
+    glViewport( 0, 0, buffer->width, buffer->height );
+    
+    return TRUE;
+}
+
+/**
+ * Render the texture holding the given buffer to the front window
+ * buffer.
+ */
+static gboolean gl_fbo_display_render_buffer( render_buffer_t buffer )
+{
+    glFinish();
+    glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 ); // real window
+    glViewport( 0, 0, video_width, video_height );
+    glEnable( GL_TEXTURE_RECTANGLE_ARB );
+    glBindTexture( GL_TEXTURE_RECTANGLE_ARB, buffer->buf_id );
+    glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE );
+    glDrawBuffer( GL_FRONT );
+    glReadBuffer( GL_FRONT );
+    glDisable( GL_ALPHA_TEST );
+    glDisable( GL_DEPTH_TEST );
+    glDisable( GL_SCISSOR_TEST );
+    glDisable( GL_CULL_FACE );
+
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+    glOrtho( 0, buffer->width, buffer->height, 0, 0, -65535 );
+    glMatrixMode(GL_MODELVIEW);
+    glLoadIdentity();
+    glEnable( GL_BLEND );
+    glBlendFunc( GL_ONE, GL_ZERO );
+    glDisable( GL_DEPTH_TEST );
+    glBegin( GL_QUADS );
+    glTexCoord2i( 0, buffer->height );
+    glVertex2f( 0.0, 0.0 );
+    glTexCoord2i( buffer->width, buffer->height );
+    glVertex2f( buffer->width, 0.0 );
+    glTexCoord2i( buffer->width, 0 );
+    glVertex2f( buffer->width, buffer->height );
+    glTexCoord2i( 0, 0 );
+    glVertex2f( 0.0, buffer->height );
+    glEnd();
+    glDisable( GL_TEXTURE_RECTANGLE_ARB );
+    glFlush();
+    return TRUE;
+}
+
+static gboolean gl_fbo_display_frame_buffer( frame_buffer_t buffer )
+{
+    glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
+    glDrawBuffer( GL_FRONT );
+    glReadBuffer( GL_FRONT );
+    return gl_display_frame_buffer( buffer );
+}
+
+static gboolean gl_fbo_display_blank( uint32_t colour )
+{
+    glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
+    glDrawBuffer( GL_FRONT );
+    glReadBuffer( GL_FRONT );
+    return gl_display_blank( colour );
+}
+
+static gboolean gl_fbo_read_render_buffer( render_buffer_t buffer, char *target )
+{
+    int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
+    GLint attach = gl_fbo_attach_texture( fb, buffer->buf_id );
+    return gl_read_render_buffer( buffer, target );
+}
+