2 * Mesa 3-D graphics library
4 * Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included
14 * in all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
28 * glReadBuffer, DrawBuffer functions.
46 * Return bitmask of BUFFER_BIT_* flags indicating which color buffers are
47 * available to the rendering context (for drawing or reading).
48 * This depends on the type of framebuffer. For window system framebuffers
49 * we look at the framebuffer's visual. But for user-create framebuffers we
50 * look at the number of supported color attachments.
51 * \param fb the framebuffer to draw to, or read from
52 * \return bitmask of BUFFER_BIT_* flags
55 supported_buffer_bitmask(const struct gl_context
*ctx
,
56 const struct gl_framebuffer
*fb
)
58 GLbitfield mask
= 0x0;
60 if (_mesa_is_user_fbo(fb
)) {
61 /* A user-created renderbuffer */
63 for (i
= 0; i
< ctx
->Const
.MaxColorAttachments
; i
++) {
64 mask
|= (BUFFER_BIT_COLOR0
<< i
);
68 /* A window system framebuffer */
70 mask
= BUFFER_BIT_FRONT_LEFT
; /* always have this */
71 if (fb
->Visual
.stereoMode
) {
72 mask
|= BUFFER_BIT_FRONT_RIGHT
;
73 if (fb
->Visual
.doubleBufferMode
) {
74 mask
|= BUFFER_BIT_BACK_LEFT
| BUFFER_BIT_BACK_RIGHT
;
77 else if (fb
->Visual
.doubleBufferMode
) {
78 mask
|= BUFFER_BIT_BACK_LEFT
;
81 for (i
= 0; i
< fb
->Visual
.numAuxBuffers
; i
++) {
82 mask
|= (BUFFER_BIT_AUX0
<< i
);
91 * Helper routine used by glDrawBuffer and glDrawBuffersARB.
92 * Given a GLenum naming one or more color buffers (such as
93 * GL_FRONT_AND_BACK), return the corresponding bitmask of BUFFER_BIT_* flags.
96 draw_buffer_enum_to_bitmask(const struct gl_context
*ctx
, GLenum buffer
)
102 return BUFFER_BIT_FRONT_LEFT
| BUFFER_BIT_FRONT_RIGHT
;
104 if (_mesa_is_gles(ctx
)) {
105 /* Page 181 (page 192 of the PDF) in section 4.2.1 of the OpenGL
106 * ES 3.0.1 specification says:
108 * "When draw buffer zero is BACK, color values are written
109 * into the sole buffer for single-buffered contexts, or into
110 * the back buffer for double-buffered contexts."
112 * Since there is no stereo rendering in ES 3.0, only return the
113 * LEFT bits. This also satisfies the "n must be 1" requirement.
115 * We also do this for GLES 1 and 2 because those APIs have no
116 * concept of selecting the front and back buffer anyway and it's
117 * convenient to be able to maintain the magic behaviour of
118 * GL_BACK in that case.
120 if (ctx
->DrawBuffer
->Visual
.doubleBufferMode
)
121 return BUFFER_BIT_BACK_LEFT
;
122 return BUFFER_BIT_FRONT_LEFT
;
124 return BUFFER_BIT_BACK_LEFT
| BUFFER_BIT_BACK_RIGHT
;
126 return BUFFER_BIT_FRONT_RIGHT
| BUFFER_BIT_BACK_RIGHT
;
128 return BUFFER_BIT_FRONT_RIGHT
;
130 return BUFFER_BIT_BACK_RIGHT
;
132 return BUFFER_BIT_BACK_LEFT
;
133 case GL_FRONT_AND_BACK
:
134 return BUFFER_BIT_FRONT_LEFT
| BUFFER_BIT_BACK_LEFT
135 | BUFFER_BIT_FRONT_RIGHT
| BUFFER_BIT_BACK_RIGHT
;
137 return BUFFER_BIT_FRONT_LEFT
| BUFFER_BIT_BACK_LEFT
;
139 return BUFFER_BIT_FRONT_LEFT
;
141 return BUFFER_BIT_AUX0
;
145 return 1 << BUFFER_COUNT
; /* invalid, but not BAD_MASK */
146 case GL_COLOR_ATTACHMENT0_EXT
:
147 return BUFFER_BIT_COLOR0
;
148 case GL_COLOR_ATTACHMENT1_EXT
:
149 return BUFFER_BIT_COLOR1
;
150 case GL_COLOR_ATTACHMENT2_EXT
:
151 return BUFFER_BIT_COLOR2
;
152 case GL_COLOR_ATTACHMENT3_EXT
:
153 return BUFFER_BIT_COLOR3
;
154 case GL_COLOR_ATTACHMENT4_EXT
:
155 return BUFFER_BIT_COLOR4
;
156 case GL_COLOR_ATTACHMENT5_EXT
:
157 return BUFFER_BIT_COLOR5
;
158 case GL_COLOR_ATTACHMENT6_EXT
:
159 return BUFFER_BIT_COLOR6
;
160 case GL_COLOR_ATTACHMENT7_EXT
:
161 return BUFFER_BIT_COLOR7
;
170 * Helper routine used by glReadBuffer.
171 * Given a GLenum naming a color buffer, return the index of the corresponding
172 * renderbuffer (a BUFFER_* value).
173 * return -1 for an invalid buffer.
176 read_buffer_enum_to_index(GLenum buffer
)
180 return BUFFER_FRONT_LEFT
;
182 return BUFFER_BACK_LEFT
;
184 return BUFFER_FRONT_RIGHT
;
186 return BUFFER_FRONT_RIGHT
;
188 return BUFFER_BACK_RIGHT
;
190 return BUFFER_BACK_LEFT
;
192 return BUFFER_FRONT_LEFT
;
194 return BUFFER_FRONT_LEFT
;
200 return BUFFER_COUNT
; /* invalid, but not -1 */
201 case GL_COLOR_ATTACHMENT0_EXT
:
202 return BUFFER_COLOR0
;
203 case GL_COLOR_ATTACHMENT1_EXT
:
204 return BUFFER_COLOR1
;
205 case GL_COLOR_ATTACHMENT2_EXT
:
206 return BUFFER_COLOR2
;
207 case GL_COLOR_ATTACHMENT3_EXT
:
208 return BUFFER_COLOR3
;
209 case GL_COLOR_ATTACHMENT4_EXT
:
210 return BUFFER_COLOR4
;
211 case GL_COLOR_ATTACHMENT5_EXT
:
212 return BUFFER_COLOR5
;
213 case GL_COLOR_ATTACHMENT6_EXT
:
214 return BUFFER_COLOR6
;
215 case GL_COLOR_ATTACHMENT7_EXT
:
216 return BUFFER_COLOR7
;
225 * Called by glDrawBuffer().
226 * Specify which renderbuffer(s) to draw into for the first color output.
227 * <buffer> can name zero, one, two or four renderbuffers!
228 * \sa _mesa_DrawBuffers
230 * \param buffer buffer token such as GL_LEFT or GL_FRONT_AND_BACK, etc.
232 * Note that the behaviour of this function depends on whether the
233 * current ctx->DrawBuffer is a window-system framebuffer or a user-created
234 * framebuffer object.
235 * In the former case, we update the per-context ctx->Color.DrawBuffer
236 * state var _and_ the FB's ColorDrawBuffer state.
237 * In the later case, we update the FB's ColorDrawBuffer state only.
239 * Furthermore, upon a MakeCurrent() or BindFramebuffer() call, if the
240 * new FB is a window system FB, we need to re-update the FB's
241 * ColorDrawBuffer state to match the context. This is handled in
242 * _mesa_update_framebuffer().
244 * See the GL_EXT_framebuffer_object spec for more info.
247 _mesa_DrawBuffer(GLenum buffer
)
250 GET_CURRENT_CONTEXT(ctx
);
252 FLUSH_VERTICES(ctx
, 0);
254 if (MESA_VERBOSE
& VERBOSE_API
) {
255 _mesa_debug(ctx
, "glDrawBuffer %s\n", _mesa_lookup_enum_by_nr(buffer
));
258 if (buffer
== GL_NONE
) {
262 const GLbitfield supportedMask
263 = supported_buffer_bitmask(ctx
, ctx
->DrawBuffer
);
264 destMask
= draw_buffer_enum_to_bitmask(ctx
, buffer
);
265 if (destMask
== BAD_MASK
) {
266 /* totally bogus buffer */
267 _mesa_error(ctx
, GL_INVALID_ENUM
,
268 "glDrawBuffer(buffer=0x%x)", buffer
);
271 destMask
&= supportedMask
;
272 if (destMask
== 0x0) {
273 /* none of the named color buffers exist! */
274 _mesa_error(ctx
, GL_INVALID_OPERATION
,
275 "glDrawBuffer(buffer=0x%x)", buffer
);
280 /* if we get here, there's no error so set new state */
281 _mesa_drawbuffers(ctx
, 1, &buffer
, &destMask
);
284 * Call device driver function.
286 if (ctx
->Driver
.DrawBuffers
)
287 ctx
->Driver
.DrawBuffers(ctx
, 1, &buffer
);
288 else if (ctx
->Driver
.DrawBuffer
)
289 ctx
->Driver
.DrawBuffer(ctx
, buffer
);
294 * Called by glDrawBuffersARB; specifies the destination color renderbuffers
295 * for N fragment program color outputs.
296 * \sa _mesa_DrawBuffer
297 * \param n number of outputs
298 * \param buffers array [n] of renderbuffer names. Unlike glDrawBuffer, the
299 * names cannot specify more than one buffer. For example,
300 * GL_FRONT_AND_BACK is illegal.
303 _mesa_DrawBuffers(GLsizei n
, const GLenum
*buffers
)
306 GLbitfield usedBufferMask
, supportedMask
;
307 GLbitfield destMask
[MAX_DRAW_BUFFERS
];
308 GET_CURRENT_CONTEXT(ctx
);
310 FLUSH_VERTICES(ctx
, 0);
312 /* Turns out n==0 is a valid input that should not produce an error.
313 * The remaining code below correctly handles the n==0 case.
315 * From the OpenGL 3.0 specification, page 258:
316 * "An INVALID_VALUE error is generated if n is greater than
319 if (n
< 0 || n
> (GLsizei
) ctx
->Const
.MaxDrawBuffers
) {
320 _mesa_error(ctx
, GL_INVALID_VALUE
, "glDrawBuffersARB(n)");
324 supportedMask
= supported_buffer_bitmask(ctx
, ctx
->DrawBuffer
);
325 usedBufferMask
= 0x0;
327 /* From the ES 3.0 specification, page 180:
328 * "If the GL is bound to the default framebuffer, then n must be 1
329 * and the constant must be BACK or NONE."
331 if (_mesa_is_gles3(ctx
) && _mesa_is_winsys_fbo(ctx
->DrawBuffer
) &&
332 (n
!= 1 || (buffers
[0] != GL_NONE
&& buffers
[0] != GL_BACK
))) {
333 _mesa_error(ctx
, GL_INVALID_OPERATION
, "glDrawBuffers(buffer)");
337 /* complicated error checking... */
338 for (output
= 0; output
< n
; output
++) {
339 if (buffers
[output
] == GL_NONE
) {
340 destMask
[output
] = 0x0;
343 /* Page 259 (page 275 of the PDF) in section 4.2.1 of the OpenGL 3.0
344 * spec (20080923) says:
346 * "If the GL is bound to a framebuffer object and DrawBuffers is
347 * supplied with [...] COLOR_ATTACHMENTm where m is greater than
348 * or equal to the value of MAX_COLOR_ATTACHMENTS, then the error
349 * INVALID_OPERATION results."
351 if (_mesa_is_user_fbo(ctx
->DrawBuffer
) && buffers
[output
] >=
352 GL_COLOR_ATTACHMENT0
+ ctx
->Const
.MaxDrawBuffers
) {
353 _mesa_error(ctx
, GL_INVALID_OPERATION
, "glDrawBuffersARB(buffer)");
357 destMask
[output
] = draw_buffer_enum_to_bitmask(ctx
, buffers
[output
]);
359 /* From the OpenGL 3.0 specification, page 258:
360 * "Each buffer listed in bufs must be one of the values from tables
361 * 4.5 or 4.6. Otherwise, an INVALID_ENUM error is generated.
363 if (destMask
[output
] == BAD_MASK
) {
364 _mesa_error(ctx
, GL_INVALID_ENUM
, "glDrawBuffersARB(buffer)");
368 /* From the OpenGL 4.0 specification, page 256:
369 * "For both the default framebuffer and framebuffer objects, the
370 * constants FRONT, BACK, LEFT, RIGHT, and FRONT_AND_BACK are not
371 * valid in the bufs array passed to DrawBuffers, and will result in
372 * the error INVALID_ENUM. This restriction is because these
373 * constants may themselves refer to multiple buffers, as shown in
375 * Previous versions of the OpenGL specification say INVALID_OPERATION,
376 * but the Khronos conformance tests expect INVALID_ENUM.
378 if (_mesa_bitcount(destMask
[output
]) > 1) {
379 _mesa_error(ctx
, GL_INVALID_ENUM
, "glDrawBuffersARB(buffer)");
383 /* From the OpenGL 3.0 specification, page 259:
384 * "If the GL is bound to the default framebuffer and DrawBuffers is
385 * supplied with a constant (other than NONE) that does not indicate
386 * any of the color buffers allocated to the GL context by the window
387 * system, the error INVALID_OPERATION will be generated.
389 * If the GL is bound to a framebuffer object and DrawBuffers is
390 * supplied with a constant from table 4.6 [...] then the error
391 * INVALID_OPERATION results."
393 destMask
[output
] &= supportedMask
;
394 if (destMask
[output
] == 0) {
395 _mesa_error(ctx
, GL_INVALID_OPERATION
,
396 "glDrawBuffersARB(unsupported buffer)");
400 /* ES 3.0 is even more restrictive. From the ES 3.0 spec, page 180:
401 * "If the GL is bound to a framebuffer object, the ith buffer listed
402 * in bufs must be COLOR_ATTACHMENTi or NONE. [...] INVALID_OPERATION."
404 if (_mesa_is_gles3(ctx
) && _mesa_is_user_fbo(ctx
->DrawBuffer
) &&
405 buffers
[output
] != GL_NONE
&&
406 buffers
[output
] != GL_COLOR_ATTACHMENT0
+ output
) {
407 _mesa_error(ctx
, GL_INVALID_OPERATION
, "glDrawBuffers(buffer)");
411 /* From the OpenGL 3.0 specification, page 258:
412 * "Except for NONE, a buffer may not appear more than once in the
413 * array pointed to by bufs. Specifying a buffer more then once will
414 * result in the error INVALID_OPERATION."
416 if (destMask
[output
] & usedBufferMask
) {
417 _mesa_error(ctx
, GL_INVALID_OPERATION
,
418 "glDrawBuffersARB(duplicated buffer)");
423 usedBufferMask
|= destMask
[output
];
427 /* OK, if we get here, there were no errors so set the new state */
428 _mesa_drawbuffers(ctx
, n
, buffers
, destMask
);
431 * Call device driver function. Note that n can be equal to 0,
432 * in which case we don't want to reference buffers[0], which
435 if (ctx
->Driver
.DrawBuffers
)
436 ctx
->Driver
.DrawBuffers(ctx
, n
, buffers
);
437 else if (ctx
->Driver
.DrawBuffer
)
438 ctx
->Driver
.DrawBuffer(ctx
, n
> 0 ? buffers
[0] : GL_NONE
);
443 * Performs necessary state updates when _mesa_drawbuffers makes an
447 updated_drawbuffers(struct gl_context
*ctx
)
449 FLUSH_VERTICES(ctx
, _NEW_BUFFERS
);
451 if (ctx
->API
== API_OPENGL_COMPAT
&& !ctx
->Extensions
.ARB_ES2_compatibility
) {
452 struct gl_framebuffer
*fb
= ctx
->DrawBuffer
;
454 /* Flag the FBO as requiring validation. */
455 if (_mesa_is_user_fbo(fb
)) {
463 * Helper function to set the GL_DRAW_BUFFER state in the context and
464 * current FBO. Called via glDrawBuffer(), glDrawBuffersARB()
466 * All error checking will have been done prior to calling this function
467 * so nothing should go wrong at this point.
469 * \param ctx current context
470 * \param n number of color outputs to set
471 * \param buffers array[n] of colorbuffer names, like GL_LEFT.
472 * \param destMask array[n] of BUFFER_BIT_* bitmasks which correspond to the
473 * colorbuffer names. (i.e. GL_FRONT_AND_BACK =>
474 * BUFFER_BIT_FRONT_LEFT | BUFFER_BIT_BACK_LEFT).
477 _mesa_drawbuffers(struct gl_context
*ctx
, GLuint n
, const GLenum
*buffers
,
478 const GLbitfield
*destMask
)
480 struct gl_framebuffer
*fb
= ctx
->DrawBuffer
;
481 GLbitfield mask
[MAX_DRAW_BUFFERS
];
485 /* compute destMask values now */
486 const GLbitfield supportedMask
= supported_buffer_bitmask(ctx
, fb
);
488 for (output
= 0; output
< n
; output
++) {
489 mask
[output
] = draw_buffer_enum_to_bitmask(ctx
, buffers
[output
]);
490 ASSERT(mask
[output
] != BAD_MASK
);
491 mask
[output
] &= supportedMask
;
497 * If n==1, destMask[0] may have up to four bits set.
498 * Otherwise, destMask[x] can only have one bit set.
501 GLuint count
= 0, destMask0
= destMask
[0];
503 GLint bufIndex
= ffs(destMask0
) - 1;
504 if (fb
->_ColorDrawBufferIndexes
[count
] != bufIndex
) {
505 updated_drawbuffers(ctx
);
506 fb
->_ColorDrawBufferIndexes
[count
] = bufIndex
;
509 destMask0
&= ~(1 << bufIndex
);
511 fb
->ColorDrawBuffer
[0] = buffers
[0];
512 fb
->_NumColorDrawBuffers
= count
;
516 for (buf
= 0; buf
< n
; buf
++ ) {
518 GLint bufIndex
= ffs(destMask
[buf
]) - 1;
519 /* only one bit should be set in the destMask[buf] field */
520 ASSERT(_mesa_bitcount(destMask
[buf
]) == 1);
521 if (fb
->_ColorDrawBufferIndexes
[buf
] != bufIndex
) {
522 updated_drawbuffers(ctx
);
523 fb
->_ColorDrawBufferIndexes
[buf
] = bufIndex
;
528 if (fb
->_ColorDrawBufferIndexes
[buf
] != -1) {
529 updated_drawbuffers(ctx
);
530 fb
->_ColorDrawBufferIndexes
[buf
] = -1;
533 fb
->ColorDrawBuffer
[buf
] = buffers
[buf
];
535 fb
->_NumColorDrawBuffers
= count
;
538 /* set remaining outputs to -1 (GL_NONE) */
539 for (buf
= fb
->_NumColorDrawBuffers
; buf
< ctx
->Const
.MaxDrawBuffers
; buf
++) {
540 if (fb
->_ColorDrawBufferIndexes
[buf
] != -1) {
541 updated_drawbuffers(ctx
);
542 fb
->_ColorDrawBufferIndexes
[buf
] = -1;
545 for (buf
= n
; buf
< ctx
->Const
.MaxDrawBuffers
; buf
++) {
546 fb
->ColorDrawBuffer
[buf
] = GL_NONE
;
549 if (_mesa_is_winsys_fbo(fb
)) {
550 /* also set context drawbuffer state */
551 for (buf
= 0; buf
< ctx
->Const
.MaxDrawBuffers
; buf
++) {
552 if (ctx
->Color
.DrawBuffer
[buf
] != fb
->ColorDrawBuffer
[buf
]) {
553 updated_drawbuffers(ctx
);
554 ctx
->Color
.DrawBuffer
[buf
] = fb
->ColorDrawBuffer
[buf
];
562 * Update the current drawbuffer's _ColorDrawBufferIndex[] list, etc.
563 * from the context's Color.DrawBuffer[] state.
564 * Use when changing contexts.
567 _mesa_update_draw_buffers(struct gl_context
*ctx
)
569 GLenum buffers
[MAX_DRAW_BUFFERS
];
572 /* should be a window system FBO */
573 assert(_mesa_is_winsys_fbo(ctx
->DrawBuffer
));
575 for (i
= 0; i
< ctx
->Const
.MaxDrawBuffers
; i
++)
576 buffers
[i
] = ctx
->Color
.DrawBuffer
[i
];
578 _mesa_drawbuffers(ctx
, ctx
->Const
.MaxDrawBuffers
, buffers
, NULL
);
583 * Like \sa _mesa_drawbuffers(), this is a helper function for setting
584 * GL_READ_BUFFER state in the context and current FBO.
585 * \param ctx the rendering context
586 * \param buffer GL_FRONT, GL_BACK, GL_COLOR_ATTACHMENT0, etc.
587 * \param bufferIndex the numerical index corresponding to 'buffer'
590 _mesa_readbuffer(struct gl_context
*ctx
, GLenum buffer
, GLint bufferIndex
)
592 struct gl_framebuffer
*fb
= ctx
->ReadBuffer
;
594 if (_mesa_is_winsys_fbo(fb
)) {
595 /* Only update the per-context READ_BUFFER state if we're bound to
596 * a window-system framebuffer.
598 ctx
->Pixel
.ReadBuffer
= buffer
;
601 fb
->ColorReadBuffer
= buffer
;
602 fb
->_ColorReadBufferIndex
= bufferIndex
;
604 ctx
->NewState
|= _NEW_BUFFERS
;
610 * Called by glReadBuffer to set the source renderbuffer for reading pixels.
611 * \param mode color buffer such as GL_FRONT, GL_BACK, etc.
614 _mesa_ReadBuffer(GLenum buffer
)
616 struct gl_framebuffer
*fb
;
617 GLbitfield supportedMask
;
619 GET_CURRENT_CONTEXT(ctx
);
621 FLUSH_VERTICES(ctx
, 0);
623 if (MESA_VERBOSE
& VERBOSE_API
)
624 _mesa_debug(ctx
, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer
));
626 fb
= ctx
->ReadBuffer
;
628 if (MESA_VERBOSE
& VERBOSE_API
)
629 _mesa_debug(ctx
, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer
));
631 if (buffer
== GL_NONE
) {
632 /* This is legal--it means that no buffer should be bound for reading. */
636 /* general case / window-system framebuffer */
637 srcBuffer
= read_buffer_enum_to_index(buffer
);
638 if (srcBuffer
== -1) {
639 _mesa_error(ctx
, GL_INVALID_ENUM
,
640 "glReadBuffer(buffer=0x%x)", buffer
);
643 supportedMask
= supported_buffer_bitmask(ctx
, fb
);
644 if (((1 << srcBuffer
) & supportedMask
) == 0) {
645 _mesa_error(ctx
, GL_INVALID_OPERATION
,
646 "glReadBuffer(buffer=0x%x)", buffer
);
651 /* OK, all error checking has been completed now */
653 _mesa_readbuffer(ctx
, buffer
, srcBuffer
);
656 * Call device driver function.
658 if (ctx
->Driver
.ReadBuffer
)
659 (*ctx
->Driver
.ReadBuffer
)(ctx
, buffer
);