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.
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).
12 * Copyright (c) 2005 Nathan Keynes.
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.
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.
25 #define GL_GLEXT_PROTOTYPES 1
30 #include "drivers/gl_common.h"
32 #define MAX_FRAMEBUFFERS 2
33 #define MAX_TEXTURES_PER_FB 4
35 static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height );
36 static void gl_fbo_destroy_render_buffer( render_buffer_t buffer );
37 static gboolean gl_fbo_set_render_target( render_buffer_t buffer );
38 static gboolean gl_fbo_display_render_buffer( render_buffer_t buffer );
39 static void gl_fbo_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer );
40 static gboolean gl_fbo_display_blank( uint32_t colour );
41 static gboolean gl_fbo_read_render_buffer( unsigned char *target, render_buffer_t buffer, int rowstride, int format );
43 extern uint32_t video_width, video_height;
46 * Framebuffer info structure
52 GLuint tex_ids[MAX_TEXTURES_PER_FB];
56 static struct gl_fbo_info fbo[MAX_FRAMEBUFFERS];
57 const static int ATTACHMENT_POINTS[MAX_TEXTURES_PER_FB] = {
58 GL_COLOR_ATTACHMENT0_EXT, GL_COLOR_ATTACHMENT1_EXT,
59 GL_COLOR_ATTACHMENT2_EXT, GL_COLOR_ATTACHMENT3_EXT };
60 static int last_used_fbo;
62 gboolean gl_fbo_is_supported()
64 return isGLExtensionSupported("GL_EXT_framebuffer_object");
68 * Construct the initial frame buffers and allocate ids for everything.
69 * The render handling driver methods are set to the fbo versions.
71 void gl_fbo_init( display_driver_t driver )
74 GLuint fbids[MAX_FRAMEBUFFERS];
75 GLuint rbids[MAX_FRAMEBUFFERS*2]; /* depth buffer, stencil buffer per fb */
77 glGenFramebuffersEXT( MAX_FRAMEBUFFERS, &fbids[0] );
78 glGenRenderbuffersEXT( MAX_FRAMEBUFFERS*2, &rbids[0] );
79 for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
80 fbo[i].fb_id = fbids[i];
81 fbo[i].depth_id = rbids[i*2];
82 fbo[i].stencil_id = rbids[i*2+1];
85 for( j=0; j<MAX_TEXTURES_PER_FB; j++ ) {
86 fbo[i].tex_ids[j] = -1;
91 driver->create_render_buffer = gl_fbo_create_render_buffer;
92 driver->destroy_render_buffer = gl_fbo_destroy_render_buffer;
93 driver->set_render_target = gl_fbo_set_render_target;
94 driver->display_render_buffer = gl_fbo_display_render_buffer;
95 driver->load_frame_buffer = gl_fbo_load_frame_buffer;
96 driver->display_blank = gl_fbo_display_blank;
97 driver->read_render_buffer = gl_fbo_read_render_buffer;
99 glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);
100 glDrawBuffer(GL_FRONT);
101 glReadBuffer(GL_FRONT);
104 void gl_fbo_shutdown()
107 glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
108 for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
109 glDeleteFramebuffersEXT( 1, &fbo[i].fb_id );
110 glDeleteRenderbuffersEXT( 2, &fbo[i].depth_id );
114 void gl_fbo_setup_framebuffer( int bufno, int width, int height )
116 glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo[bufno].fb_id);
117 glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
118 glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT24, width, height);
119 glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
120 GL_RENDERBUFFER_EXT, fbo[bufno].depth_id);
121 /* Stencil doesn't work on ATI, and we're not using it at the moment anyway, so...
122 glBindRenderbufferEXT(GL_RENDERBUFFER_EXT, fbo[bufno].stencil_id);
123 glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, GL_STENCIL_INDEX, width, height);
124 glFramebufferRenderbufferEXT(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
125 GL_RENDERBUFFER_EXT, fbo[bufno].stencil_id);
127 fbo[bufno].width = width;
128 fbo[bufno].height = height;
131 int gl_fbo_get_framebuffer( int width, int height )
134 /* find a compatible framebuffer context */
135 for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
136 if( fbo[i].width == -1 && bufno == -1 ) {
138 } else if( fbo[i].width == width && fbo[i].height == height ) {
144 bufno = last_used_fbo + 1;
145 if( bufno > MAX_FRAMEBUFFERS ) {
148 last_used_fbo = bufno;
150 if( fbo[bufno].width == width && fbo[bufno].height == height ) {
151 glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, fbo[bufno].fb_id );
153 gl_fbo_setup_framebuffer( bufno, width, height );
159 * Attach a texture to the framebuffer. The texture must already be initialized
160 * to the correct dimensions etc.
162 static GLint gl_fbo_attach_texture( int fbo_no, GLint tex_id ) {
164 for( i=0; i<MAX_TEXTURES_PER_FB; i++ ) {
165 if( fbo[fbo_no].tex_ids[i] == tex_id ) {
166 glDrawBuffer(ATTACHMENT_POINTS[i]);
167 glReadBuffer(ATTACHMENT_POINTS[i]);
168 return ATTACHMENT_POINTS[i]; // already attached
169 } else if( fbo[fbo_no].tex_ids[i] == -1 && attach == -1 ) {
174 /* should never happen */
177 fbo[fbo_no].tex_ids[attach] = tex_id;
178 glBindTexture( GL_TEXTURE_RECTANGLE_ARB, 0 ); // Ensure the output texture is unbound
179 glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, ATTACHMENT_POINTS[attach],
180 GL_TEXTURE_RECTANGLE_ARB, tex_id, 0 );
181 /* Set draw/read buffers by default */
182 glDrawBuffer(ATTACHMENT_POINTS[attach]);
183 glReadBuffer(ATTACHMENT_POINTS[attach]);
186 GLint status = glGetError();
187 if( status != GL_NO_ERROR ) {
188 ERROR( "GL error setting render target (%x)!", status );
190 status = glCheckFramebufferStatusEXT(GL_FRAMEBUFFER_EXT);
191 if( status != GL_FRAMEBUFFER_COMPLETE_EXT ) {
192 ERROR( "Framebuffer failure: %x", status );
196 return ATTACHMENT_POINTS[attach];
199 static render_buffer_t gl_fbo_create_render_buffer( uint32_t width, uint32_t height )
201 render_buffer_t buffer = calloc( sizeof(struct render_buffer), 1 );
202 buffer->width = width;
203 buffer->height = height;
204 glGenTextures( 1, &buffer->buf_id );
205 glBindTexture( GL_TEXTURE_RECTANGLE_ARB, buffer->buf_id );
206 glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_S, GL_CLAMP );
207 glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_WRAP_T, GL_CLAMP );
208 glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
209 glTexParameteri( GL_TEXTURE_RECTANGLE_ARB, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
210 glTexImage2D( GL_TEXTURE_RECTANGLE_ARB, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );
214 static void gl_fbo_destroy_render_buffer( render_buffer_t buffer )
217 for( i=0; i<MAX_FRAMEBUFFERS; i++ ) {
218 for( j=0; j < MAX_TEXTURES_PER_FB; j++ ) {
219 if( fbo[i].tex_ids[j] == buffer->buf_id ) {
220 glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, fbo[i].fb_id);
221 glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, ATTACHMENT_POINTS[j],
222 GL_TEXTURE_RECTANGLE_ARB, GL_NONE, 0 );
223 fbo[i].tex_ids[j] = -1;
228 glDeleteTextures( 1, &buffer->buf_id );
233 static gboolean gl_fbo_set_render_target( render_buffer_t buffer )
237 int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
238 gl_fbo_attach_texture( fb, buffer->buf_id );
239 /* setup the gl context */
240 glViewport( 0, 0, buffer->width, buffer->height );
246 * Render the texture holding the given buffer to the front window
249 static gboolean gl_fbo_display_render_buffer( render_buffer_t buffer )
253 gl_display_render_buffer( buffer );
257 static void gl_fbo_load_frame_buffer( frame_buffer_t frame, render_buffer_t buffer )
261 gl_load_frame_buffer( frame, buffer->buf_id );
264 static gboolean gl_fbo_display_blank( uint32_t colour )
268 return gl_display_blank( colour );
273 glBindFramebufferEXT( GL_FRAMEBUFFER_EXT, 0 );
274 glDrawBuffer( GL_FRONT );
275 glReadBuffer( GL_FRONT );
278 static gboolean gl_fbo_read_render_buffer( unsigned char *target, render_buffer_t buffer,
279 int rowstride, int format )
281 int fb = gl_fbo_get_framebuffer( buffer->width, buffer->height );
282 gl_fbo_attach_texture( fb, buffer->buf_id );
283 return gl_read_render_buffer( target, buffer, rowstride, format );
.