1 /* $Id: s_accum.c,v 1.19 2002/10/24 23:57:24 brianp Exp $ */
4 * Mesa 3-D graphics library
7 * Copyright (C) 1999-2002 Brian Paul All Rights Reserved.
9 * Permission is hereby granted, free of charge, to any person obtaining a
10 * copy of this software and associated documentation files (the "Software"),
11 * to deal in the Software without restriction, including without limitation
12 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
13 * and/or sell copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following conditions:
16 * The above copyright notice and this permission notice shall be included
17 * in all copies or substantial portions of the Software.
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
20 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
22 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
23 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
24 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
35 #include "s_alphabuf.h"
36 #include "s_context.h"
37 #include "s_masking.h"
42 * Accumulation buffer notes
44 * Normally, accumulation buffer values are GLshorts with values in
45 * [-32767, 32767] which represent floating point colors in [-1, 1],
46 * as suggested by the OpenGL specification.
48 * We optimize for the common case used for full-scene antialiasing:
49 * // start with accum buffer cleared to zero
50 * glAccum(GL_LOAD, w); // or GL_ACCUM the first image
51 * glAccum(GL_ACCUM, w);
53 * glAccum(GL_ACCUM, w);
54 * glAccum(GL_RETURN, 1.0);
55 * That is, we start with an empty accumulation buffer and accumulate
56 * n images, each with weight w = 1/n.
57 * In this scenario, we can simply store unscaled integer values in
58 * the accum buffer instead of scaled integers. We'll also keep track
59 * of the w value so when we do GL_RETURN we simply divide the accumulated
61 * This lets us avoid _many_ int->float->int conversions.
65 #if CHAN_BITS == 8 && ACCUM_BITS < 32
66 #define USE_OPTIMIZED_ACCUM /* enable the optimization */
71 _mesa_alloc_accum_buffer( GLframebuffer
*buffer
)
73 GET_CURRENT_CONTEXT(ctx
);
77 MESA_PBUFFER_FREE( buffer
->Accum
);
81 /* allocate accumulation buffer if not already present */
82 n
= buffer
->Width
* buffer
->Height
* 4 * sizeof(GLaccum
);
83 buffer
->Accum
= (GLaccum
*) MESA_PBUFFER_ALLOC( n
);
85 /* unable to setup accumulation buffer */
86 _mesa_error( NULL
, GL_OUT_OF_MEMORY
, "glAccum" );
90 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
91 /* XXX these fields should probably be in the GLframebuffer */
92 #ifdef USE_OPTIMIZED_ACCUM
93 swrast
->_IntegerAccumMode
= GL_TRUE
;
95 swrast
->_IntegerAccumMode
= GL_FALSE
;
97 swrast
->_IntegerAccumScaler
= 0.0;
103 * This is called when we fall out of optimized/unscaled accum buffer mode.
104 * That is, we convert each unscaled accum buffer value into a scaled value
105 * representing the range[-1, 1].
107 static void rescale_accum( GLcontext
*ctx
)
109 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
110 const GLuint n
= ctx
->DrawBuffer
->Width
* ctx
->DrawBuffer
->Height
* 4;
111 const GLfloat s
= swrast
->_IntegerAccumScaler
* (32767.0F
/ CHAN_MAXF
);
112 GLaccum
*accum
= ctx
->DrawBuffer
->Accum
;
115 assert(swrast
->_IntegerAccumMode
);
118 for (i
= 0; i
< n
; i
++) {
119 accum
[i
] = (GLaccum
) (accum
[i
] * s
);
122 swrast
->_IntegerAccumMode
= GL_FALSE
;
131 * Clear the accumulation Buffer.
134 _mesa_clear_accum_buffer( GLcontext
*ctx
)
136 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
140 if (ctx
->Visual
.accumRedBits
==0) {
141 /* No accumulation buffer! */
145 if (sizeof(GLaccum
)==1) {
148 else if (sizeof(GLaccum
)==2) {
155 /* number of pixels */
156 buffersize
= ctx
->DrawBuffer
->Width
* ctx
->DrawBuffer
->Height
;
158 if (!ctx
->DrawBuffer
->Accum
) {
159 /* try to alloc accumulation buffer */
160 ctx
->DrawBuffer
->Accum
= (GLaccum
*)
161 MALLOC( buffersize
* 4 * sizeof(GLaccum
) );
164 if (ctx
->DrawBuffer
->Accum
) {
165 if (ctx
->Scissor
.Enabled
) {
166 /* Limit clear to scissor box */
167 const GLaccum r
= (GLaccum
) (ctx
->Accum
.ClearColor
[0] * acc_scale
);
168 const GLaccum g
= (GLaccum
) (ctx
->Accum
.ClearColor
[1] * acc_scale
);
169 const GLaccum b
= (GLaccum
) (ctx
->Accum
.ClearColor
[2] * acc_scale
);
170 const GLaccum a
= (GLaccum
) (ctx
->Accum
.ClearColor
[3] * acc_scale
);
174 /* size of region to clear */
175 width
= 4 * (ctx
->DrawBuffer
->_Xmax
- ctx
->DrawBuffer
->_Xmin
);
176 height
= ctx
->DrawBuffer
->_Ymax
- ctx
->DrawBuffer
->_Ymin
;
177 /* ptr to first element to clear */
178 row
= ctx
->DrawBuffer
->Accum
179 + 4 * (ctx
->DrawBuffer
->_Ymin
* ctx
->DrawBuffer
->Width
180 + ctx
->DrawBuffer
->_Xmin
);
181 for (j
=0;j
<height
;j
++) {
182 for (i
=0;i
<width
;i
+=4) {
188 row
+= 4 * ctx
->DrawBuffer
->Width
;
192 /* clear whole buffer */
193 if (ctx
->Accum
.ClearColor
[0]==0.0 &&
194 ctx
->Accum
.ClearColor
[1]==0.0 &&
195 ctx
->Accum
.ClearColor
[2]==0.0 &&
196 ctx
->Accum
.ClearColor
[3]==0.0) {
198 BZERO( ctx
->DrawBuffer
->Accum
, buffersize
* 4 * sizeof(GLaccum
) );
202 const GLaccum r
= (GLaccum
) (ctx
->Accum
.ClearColor
[0] * acc_scale
);
203 const GLaccum g
= (GLaccum
) (ctx
->Accum
.ClearColor
[1] * acc_scale
);
204 const GLaccum b
= (GLaccum
) (ctx
->Accum
.ClearColor
[2] * acc_scale
);
205 const GLaccum a
= (GLaccum
) (ctx
->Accum
.ClearColor
[3] * acc_scale
);
206 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
;
208 for (i
=0;i
<buffersize
;i
++) {
217 /* update optimized accum state vars */
218 if (ctx
->Accum
.ClearColor
[0] == 0.0 && ctx
->Accum
.ClearColor
[1] == 0.0 &&
219 ctx
->Accum
.ClearColor
[2] == 0.0 && ctx
->Accum
.ClearColor
[3] == 0.0) {
220 #ifdef USE_OPTIMIZED_ACCUM
221 swrast
->_IntegerAccumMode
= GL_TRUE
;
223 swrast
->_IntegerAccumMode
= GL_FALSE
;
225 swrast
->_IntegerAccumScaler
= 0.0; /* denotes empty accum buffer */
228 swrast
->_IntegerAccumMode
= GL_FALSE
;
235 _swrast_Accum( GLcontext
*ctx
, GLenum op
, GLfloat value
,
236 GLint xpos
, GLint ypos
,
237 GLint width
, GLint height
)
240 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
243 GLchan rgba
[MAX_WIDTH
][4];
244 const GLuint colorMask
= *((GLuint
*) &ctx
->Color
.ColorMask
);
247 if (SWRAST_CONTEXT(ctx
)->NewState
)
248 _swrast_validate_derived( ctx
);
250 if (!ctx
->DrawBuffer
->Accum
) {
252 "Calling glAccum() without an accumulation "
253 "buffer (low memory?)");
257 if (sizeof(GLaccum
)==1) {
260 else if (sizeof(GLaccum
)==2) {
272 const GLaccum val
= (GLaccum
) (value
* acc_scale
);
274 /* Leave optimized accum buffer mode */
275 if (swrast
->_IntegerAccumMode
)
277 for (j
= 0; j
< height
; j
++) {
278 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ 4*xpos
;
280 for (i
= 0; i
< width4
; i
++) {
291 /* Leave optimized accum buffer mode */
292 if (swrast
->_IntegerAccumMode
)
294 for (j
= 0; j
< height
; j
++) {
295 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ 4 * xpos
;
297 for (i
= 0; i
< width4
; i
++) {
298 acc
[i
] = (GLaccum
) ( (GLfloat
) acc
[i
] * value
);
309 _swrast_use_read_buffer(ctx
);
311 /* May have to leave optimized accum buffer mode */
312 if (swrast
->_IntegerAccumScaler
== 0.0 && value
> 0.0 && value
<= 1.0)
313 swrast
->_IntegerAccumScaler
= value
;
314 if (swrast
->_IntegerAccumMode
&& value
!= swrast
->_IntegerAccumScaler
)
317 RENDER_START(swrast
,ctx
);
319 if (swrast
->_IntegerAccumMode
) {
320 /* simply add integer color values into accum buffer */
322 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ xpos
* 4;
323 assert(swrast
->_IntegerAccumScaler
> 0.0);
324 assert(swrast
->_IntegerAccumScaler
<= 1.0);
325 for (j
= 0; j
< height
; j
++) {
328 _mesa_read_rgba_span(ctx
, ctx
->DrawBuffer
, width
, xpos
, ypos
, rgba
);
329 for (i
= i4
= 0; i
< width
; i
++, i4
+=4) {
330 acc
[i4
+0] += rgba
[i
][RCOMP
];
331 acc
[i4
+1] += rgba
[i
][GCOMP
];
332 acc
[i4
+2] += rgba
[i
][BCOMP
];
333 acc
[i4
+3] += rgba
[i
][ACOMP
];
340 /* scaled integer (or float) accum buffer */
341 const GLfloat rscale
= value
* acc_scale
/ CHAN_MAXF
;
342 const GLfloat gscale
= value
* acc_scale
/ CHAN_MAXF
;
343 const GLfloat bscale
= value
* acc_scale
/ CHAN_MAXF
;
344 const GLfloat ascale
= value
* acc_scale
/ CHAN_MAXF
;
346 for (j
=0;j
<height
;j
++) {
347 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ xpos
* 4;
349 _mesa_read_rgba_span(ctx
, ctx
->DrawBuffer
, width
, xpos
, ypos
, rgba
);
350 for (i
=0;i
<width
;i
++) {
351 acc
[0] += (GLaccum
) ( (GLfloat
) rgba
[i
][RCOMP
] * rscale
);
352 acc
[1] += (GLaccum
) ( (GLfloat
) rgba
[i
][GCOMP
] * gscale
);
353 acc
[2] += (GLaccum
) ( (GLfloat
) rgba
[i
][BCOMP
] * bscale
);
354 acc
[3] += (GLaccum
) ( (GLfloat
) rgba
[i
][ACOMP
] * ascale
);
360 /* restore read buffer = draw buffer (the default) */
361 _swrast_use_draw_buffer(ctx
);
363 RENDER_FINISH(swrast
,ctx
);
367 _swrast_use_read_buffer(ctx
);
369 /* This is a change to go into optimized accum buffer mode */
370 if (value
> 0.0 && value
<= 1.0) {
371 #ifdef USE_OPTIMIZED_ACCUM
372 swrast
->_IntegerAccumMode
= GL_TRUE
;
374 swrast
->_IntegerAccumMode
= GL_FALSE
;
376 swrast
->_IntegerAccumScaler
= value
;
379 swrast
->_IntegerAccumMode
= GL_FALSE
;
380 swrast
->_IntegerAccumScaler
= 0.0;
383 RENDER_START(swrast
,ctx
);
384 if (swrast
->_IntegerAccumMode
) {
385 /* just copy values into accum buffer */
387 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ xpos
* 4;
388 assert(swrast
->_IntegerAccumScaler
> 0.0);
389 assert(swrast
->_IntegerAccumScaler
<= 1.0);
390 for (j
= 0; j
< height
; j
++) {
392 _mesa_read_rgba_span(ctx
, ctx
->DrawBuffer
, width
, xpos
, ypos
, rgba
);
393 for (i
= i4
= 0; i
< width
; i
++, i4
+= 4) {
394 acc
[i4
+0] = rgba
[i
][RCOMP
];
395 acc
[i4
+1] = rgba
[i
][GCOMP
];
396 acc
[i4
+2] = rgba
[i
][BCOMP
];
397 acc
[i4
+3] = rgba
[i
][ACOMP
];
404 /* scaled integer (or float) accum buffer */
405 const GLfloat rscale
= value
* acc_scale
/ CHAN_MAXF
;
406 const GLfloat gscale
= value
* acc_scale
/ CHAN_MAXF
;
407 const GLfloat bscale
= value
* acc_scale
/ CHAN_MAXF
;
408 const GLfloat ascale
= value
* acc_scale
/ CHAN_MAXF
;
410 const GLfloat d
= 3.0 / acc_scale
; /* XXX what's this? */
413 for (j
= 0; j
< height
; j
++) {
414 GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ xpos
* 4;
415 _mesa_read_rgba_span(ctx
, ctx
->DrawBuffer
, width
, xpos
, ypos
, rgba
);
416 for (i
=0;i
<width
;i
++) {
418 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][RCOMP
] * rscale
+ d
);
419 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][GCOMP
] * gscale
+ d
);
420 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][BCOMP
] * bscale
+ d
);
421 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][ACOMP
] * ascale
+ d
);
423 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][RCOMP
] * rscale
);
424 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][GCOMP
] * gscale
);
425 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][BCOMP
] * bscale
);
426 *acc
++ = (GLaccum
) ((GLfloat
) rgba
[i
][ACOMP
] * ascale
);
433 /* restore read buffer = draw buffer (the default) */
434 _swrast_use_draw_buffer(ctx
);
436 RENDER_FINISH(swrast
,ctx
);
440 /* May have to leave optimized accum buffer mode */
441 if (swrast
->_IntegerAccumMode
&& value
!= 1.0)
444 RENDER_START(swrast
,ctx
);
445 #ifdef USE_OPTIMIZED_ACCUM
446 if (swrast
->_IntegerAccumMode
&& swrast
->_IntegerAccumScaler
> 0) {
447 /* build lookup table to avoid many floating point multiplies */
448 static GLchan multTable
[32768];
449 static GLfloat prevMult
= 0.0;
450 const GLfloat mult
= swrast
->_IntegerAccumScaler
;
451 const GLint max
= MIN2((GLint
) (256 / mult
), 32767);
453 if (mult
!= prevMult
) {
454 for (j
= 0; j
< max
; j
++)
455 multTable
[j
] = IROUND((GLfloat
) j
* mult
);
459 assert(swrast
->_IntegerAccumScaler
> 0.0);
460 assert(swrast
->_IntegerAccumScaler
<= 1.0);
461 for (j
= 0; j
< height
; j
++) {
462 const GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ xpos
*4;
464 for (i
= i4
= 0; i
< width
; i
++, i4
+= 4) {
465 ASSERT(acc
[i4
+0] < max
);
466 ASSERT(acc
[i4
+1] < max
);
467 ASSERT(acc
[i4
+2] < max
);
468 ASSERT(acc
[i4
+3] < max
);
469 rgba
[i
][RCOMP
] = multTable
[acc
[i4
+0]];
470 rgba
[i
][GCOMP
] = multTable
[acc
[i4
+1]];
471 rgba
[i
][BCOMP
] = multTable
[acc
[i4
+2]];
472 rgba
[i
][ACOMP
] = multTable
[acc
[i4
+3]];
474 if (colorMask
!= 0xffffffff) {
475 _mesa_mask_rgba_array( ctx
, width
, xpos
, ypos
, rgba
);
477 (*swrast
->Driver
.WriteRGBASpan
)( ctx
, width
, xpos
, ypos
,
478 (const GLchan (*)[4])rgba
, NULL
);
479 if (ctx
->DrawBuffer
->UseSoftwareAlphaBuffers
480 && ctx
->Color
.ColorMask
[ACOMP
]) {
481 _mesa_write_alpha_span(ctx
, width
, xpos
, ypos
,
482 (CONST
GLchan (*)[4]) rgba
, NULL
);
488 #endif /* USE_OPTIMIZED_ACCUM */
490 /* scaled integer (or float) accum buffer */
491 const GLfloat rscale
= value
/ acc_scale
* CHAN_MAXF
;
492 const GLfloat gscale
= value
/ acc_scale
* CHAN_MAXF
;
493 const GLfloat bscale
= value
/ acc_scale
* CHAN_MAXF
;
494 const GLfloat ascale
= value
/ acc_scale
* CHAN_MAXF
;
496 for (j
=0;j
<height
;j
++) {
497 const GLaccum
*acc
= ctx
->DrawBuffer
->Accum
+ ypos
* width4
+ xpos
*4;
498 for (i
=0;i
<width
;i
++) {
499 GLint r
= IROUND( (GLfloat
) (acc
[0]) * rscale
);
500 GLint g
= IROUND( (GLfloat
) (acc
[1]) * gscale
);
501 GLint b
= IROUND( (GLfloat
) (acc
[2]) * bscale
);
502 GLint a
= IROUND( (GLfloat
) (acc
[3]) * ascale
);
504 rgba
[i
][RCOMP
] = CLAMP( r
, 0, CHAN_MAX
);
505 rgba
[i
][GCOMP
] = CLAMP( g
, 0, CHAN_MAX
);
506 rgba
[i
][BCOMP
] = CLAMP( b
, 0, CHAN_MAX
);
507 rgba
[i
][ACOMP
] = CLAMP( a
, 0, CHAN_MAX
);
509 if (colorMask
!= 0xffffffff) {
510 _mesa_mask_rgba_array( ctx
, width
, xpos
, ypos
, rgba
);
512 (*swrast
->Driver
.WriteRGBASpan
)( ctx
, width
, xpos
, ypos
,
513 (const GLchan (*)[4])rgba
, NULL
);
514 if (ctx
->DrawBuffer
->UseSoftwareAlphaBuffers
515 && ctx
->Color
.ColorMask
[ACOMP
]) {
516 _mesa_write_alpha_span(ctx
, width
, xpos
, ypos
,
517 (CONST
GLchan (*)[4]) rgba
, NULL
);
522 RENDER_FINISH(swrast
,ctx
);
526 _mesa_error( ctx
, GL_INVALID_ENUM
, "glAccum" );