2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
21 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29 #include "swrast/s_aaline.h"
30 #include "swrast/s_context.h"
31 #include "swrast/s_span.h"
32 #include "swrast/swrast.h"
40 * Info about the AA line we're rendering
44 GLfloat x0
, y0
; /* start */
45 GLfloat x1
, y1
; /* end */
46 GLfloat dx
, dy
; /* direction vector */
47 GLfloat len
; /* length */
48 GLfloat halfWidth
; /* half of line width */
49 GLfloat xAdj
, yAdj
; /* X and Y adjustment for quad corners around line */
50 /* for coverage computation */
51 GLfloat qx0
, qy0
; /* quad vertices */
55 GLfloat ex0
, ey0
; /* quad edge vectors */
63 GLfloat rPlane
[4], gPlane
[4], bPlane
[4], aPlane
[4];
68 GLfloat attrPlane
[FRAG_ATTRIB_MAX
][4][4];
69 GLfloat lambda
[FRAG_ATTRIB_MAX
];
70 GLfloat texWidth
[FRAG_ATTRIB_MAX
];
71 GLfloat texHeight
[FRAG_ATTRIB_MAX
];
79 * Compute the equation of a plane used to interpolate line fragment data
80 * such as color, Z, texture coords, etc.
81 * Input: (x0, y0) and (x1,y1) are the endpoints of the line.
82 * z0, and z1 are the end point values to interpolate.
83 * Output: plane - the plane equation.
85 * Note: we don't really have enough parameters to specify a plane.
86 * We take the endpoints of the line and compute a plane such that
87 * the cross product of the line vector and the plane normal is
88 * parallel to the projection plane.
91 compute_plane(GLfloat x0
, GLfloat y0
, GLfloat x1
, GLfloat y1
,
92 GLfloat z0
, GLfloat z1
, GLfloat plane
[4])
96 const GLfloat px
= x1
- x0
;
97 const GLfloat py
= y1
- y0
;
98 const GLfloat pz
= z1
- z0
;
99 const GLfloat qx
= -py
;
100 const GLfloat qy
= px
;
101 const GLfloat qz
= 0;
102 const GLfloat a
= py
* qz
- pz
* qy
;
103 const GLfloat b
= pz
* qx
- px
* qz
;
104 const GLfloat c
= px
* qy
- py
* qx
;
105 const GLfloat d
= -(a
* x0
+ b
* y0
+ c
* z0
);
112 const GLfloat px
= x1
- x0
;
113 const GLfloat py
= y1
- y0
;
114 const GLfloat pz
= z0
- z1
;
115 const GLfloat a
= pz
* px
;
116 const GLfloat b
= pz
* py
;
117 const GLfloat c
= px
* px
+ py
* py
;
118 const GLfloat d
= -(a
* x0
+ b
* y0
+ c
* z0
);
119 if (a
== 0.0 && b
== 0.0 && c
== 0.0 && d
== 0.0) {
136 constant_plane(GLfloat value
, GLfloat plane
[4])
145 static INLINE GLfloat
146 solve_plane(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
148 const GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
152 #define SOLVE_PLANE(X, Y, PLANE) \
153 ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
157 * Return 1 / solve_plane().
159 static INLINE GLfloat
160 solve_plane_recip(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
162 const GLfloat denom
= plane
[3] + plane
[0] * x
+ plane
[1] * y
;
166 return -plane
[2] / denom
;
171 * Solve plane and return clamped GLchan value.
174 solve_plane_chan(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
176 const GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
177 #if CHAN_TYPE == GL_FLOAT
178 return CLAMP(z
, 0.0F
, CHAN_MAXF
);
182 else if (z
> CHAN_MAX
)
184 return (GLchan
) IROUND_POS(z
);
190 * Compute mipmap level of detail.
192 static INLINE GLfloat
193 compute_lambda(const GLfloat sPlane
[4], const GLfloat tPlane
[4],
194 GLfloat invQ
, GLfloat width
, GLfloat height
)
196 GLfloat dudx
= sPlane
[0] / sPlane
[2] * invQ
* width
;
197 GLfloat dudy
= sPlane
[1] / sPlane
[2] * invQ
* width
;
198 GLfloat dvdx
= tPlane
[0] / tPlane
[2] * invQ
* height
;
199 GLfloat dvdy
= tPlane
[1] / tPlane
[2] * invQ
* height
;
200 GLfloat r1
= dudx
* dudx
+ dudy
* dudy
;
201 GLfloat r2
= dvdx
* dvdx
+ dvdy
* dvdy
;
202 GLfloat rho2
= r1
+ r2
;
203 /* return log base 2 of rho */
207 return (GLfloat
) (LOGF(rho2
) * 1.442695 * 0.5);/* 1.442695 = 1/log(2) */
214 * Fill in the samples[] array with the (x,y) subpixel positions of
215 * xSamples * ySamples sample positions.
216 * Note that the four corner samples are put into the first four
217 * positions of the array. This allows us to optimize for the common
218 * case of all samples being inside the polygon.
221 make_sample_table(GLint xSamples
, GLint ySamples
, GLfloat samples
[][2])
223 const GLfloat dx
= 1.0F
/ (GLfloat
) xSamples
;
224 const GLfloat dy
= 1.0F
/ (GLfloat
) ySamples
;
229 for (x
= 0; x
< xSamples
; x
++) {
230 for (y
= 0; y
< ySamples
; y
++) {
232 if (x
== 0 && y
== 0) {
236 else if (x
== xSamples
- 1 && y
== 0) {
240 else if (x
== 0 && y
== ySamples
- 1) {
244 else if (x
== xSamples
- 1 && y
== ySamples
- 1) {
251 samples
[j
][0] = x
* dx
+ 0.5F
* dx
;
252 samples
[j
][1] = y
* dy
+ 0.5F
* dy
;
260 * Compute how much of the given pixel's area is inside the rectangle
261 * defined by vertices v0, v1, v2, v3.
262 * Vertices MUST be specified in counter-clockwise order.
263 * Return: coverage in [0, 1].
266 compute_coveragef(const struct LineInfo
*info
,
267 GLint winx
, GLint winy
)
269 static GLfloat samples
[SUB_PIXEL
* SUB_PIXEL
][2];
270 static GLboolean haveSamples
= GL_FALSE
;
271 const GLfloat x
= (GLfloat
) winx
;
272 const GLfloat y
= (GLfloat
) winy
;
274 GLfloat insideCount
= SUB_PIXEL
* SUB_PIXEL
;
277 make_sample_table(SUB_PIXEL
, SUB_PIXEL
, samples
);
278 haveSamples
= GL_TRUE
;
283 const GLfloat area
= dx0
* dy1
- dx1
* dy0
;
288 for (i
= 0; i
< stop
; i
++) {
289 const GLfloat sx
= x
+ samples
[i
][0];
290 const GLfloat sy
= y
+ samples
[i
][1];
291 const GLfloat fx0
= sx
- info
->qx0
;
292 const GLfloat fy0
= sy
- info
->qy0
;
293 const GLfloat fx1
= sx
- info
->qx1
;
294 const GLfloat fy1
= sy
- info
->qy1
;
295 const GLfloat fx2
= sx
- info
->qx2
;
296 const GLfloat fy2
= sy
- info
->qy2
;
297 const GLfloat fx3
= sx
- info
->qx3
;
298 const GLfloat fy3
= sy
- info
->qy3
;
299 /* cross product determines if sample is inside or outside each edge */
300 GLfloat cross0
= (info
->ex0
* fy0
- info
->ey0
* fx0
);
301 GLfloat cross1
= (info
->ex1
* fy1
- info
->ey1
* fx1
);
302 GLfloat cross2
= (info
->ex2
* fy2
- info
->ey2
* fx2
);
303 GLfloat cross3
= (info
->ex3
* fy3
- info
->ey3
* fx3
);
304 /* Check if the sample is exactly on an edge. If so, let cross be a
305 * positive or negative value depending on the direction of the edge.
308 cross0
= info
->ex0
+ info
->ey0
;
310 cross1
= info
->ex1
+ info
->ey1
;
312 cross2
= info
->ex2
+ info
->ey2
;
314 cross3
= info
->ex3
+ info
->ey3
;
315 if (cross0
< 0.0F
|| cross1
< 0.0F
|| cross2
< 0.0F
|| cross3
< 0.0F
) {
316 /* point is outside quadrilateral */
318 stop
= SUB_PIXEL
* SUB_PIXEL
;
324 return insideCount
* (1.0F
/ (SUB_PIXEL
* SUB_PIXEL
));
329 * Compute coverage value for color index mode.
330 * XXX this may not be quite correct.
331 * \return coverage in [0,15].
334 compute_coveragei(const struct LineInfo
*info
,
335 GLint winx
, GLint winy
)
337 return compute_coveragef(info
, winx
, winy
) * 15.0F
;
342 typedef void (*plot_func
)(GLcontext
*ctx
, struct LineInfo
*line
,
348 * Draw an AA line segment (called many times per line when stippling)
351 segment(GLcontext
*ctx
,
352 struct LineInfo
*line
,
354 GLfloat t0
, GLfloat t1
)
356 const GLfloat absDx
= (line
->dx
< 0.0F
) ? -line
->dx
: line
->dx
;
357 const GLfloat absDy
= (line
->dy
< 0.0F
) ? -line
->dy
: line
->dy
;
358 /* compute the actual segment's endpoints */
359 const GLfloat x0
= line
->x0
+ t0
* line
->dx
;
360 const GLfloat y0
= line
->y0
+ t0
* line
->dy
;
361 const GLfloat x1
= line
->x0
+ t1
* line
->dx
;
362 const GLfloat y1
= line
->y0
+ t1
* line
->dy
;
364 /* compute vertices of the line-aligned quadrilateral */
365 line
->qx0
= x0
- line
->yAdj
;
366 line
->qy0
= y0
+ line
->xAdj
;
367 line
->qx1
= x0
+ line
->yAdj
;
368 line
->qy1
= y0
- line
->xAdj
;
369 line
->qx2
= x1
+ line
->yAdj
;
370 line
->qy2
= y1
- line
->xAdj
;
371 line
->qx3
= x1
- line
->yAdj
;
372 line
->qy3
= y1
+ line
->xAdj
;
373 /* compute the quad's edge vectors (for coverage calc) */
374 line
->ex0
= line
->qx1
- line
->qx0
;
375 line
->ey0
= line
->qy1
- line
->qy0
;
376 line
->ex1
= line
->qx2
- line
->qx1
;
377 line
->ey1
= line
->qy2
- line
->qy1
;
378 line
->ex2
= line
->qx3
- line
->qx2
;
379 line
->ey2
= line
->qy3
- line
->qy2
;
380 line
->ex3
= line
->qx0
- line
->qx3
;
381 line
->ey3
= line
->qy0
- line
->qy3
;
385 GLfloat dydx
= line
->dy
/ line
->dx
;
386 GLfloat xLeft
, xRight
, yBot
, yTop
;
389 xLeft
= x0
- line
->halfWidth
;
390 xRight
= x1
+ line
->halfWidth
;
391 if (line
->dy
>= 0.0) {
392 yBot
= y0
- 3.0F
* line
->halfWidth
;
393 yTop
= y0
+ line
->halfWidth
;
396 yBot
= y0
- line
->halfWidth
;
397 yTop
= y0
+ 3.0F
* line
->halfWidth
;
401 xLeft
= x1
- line
->halfWidth
;
402 xRight
= x0
+ line
->halfWidth
;
403 if (line
->dy
<= 0.0) {
404 yBot
= y1
- 3.0F
* line
->halfWidth
;
405 yTop
= y1
+ line
->halfWidth
;
408 yBot
= y1
- line
->halfWidth
;
409 yTop
= y1
+ 3.0F
* line
->halfWidth
;
413 /* scan along the line, left-to-right */
414 ixRight
= (GLint
) (xRight
+ 1.0F
);
416 /*printf("avg span height: %g\n", yTop - yBot);*/
417 for (ix
= (GLint
) xLeft
; ix
< ixRight
; ix
++) {
418 const GLint iyBot
= (GLint
) yBot
;
419 const GLint iyTop
= (GLint
) (yTop
+ 1.0F
);
421 /* scan across the line, bottom-to-top */
422 for (iy
= iyBot
; iy
< iyTop
; iy
++) {
423 (*plot
)(ctx
, line
, ix
, iy
);
431 GLfloat dxdy
= line
->dx
/ line
->dy
;
432 GLfloat yBot
, yTop
, xLeft
, xRight
;
435 yBot
= y0
- line
->halfWidth
;
436 yTop
= y1
+ line
->halfWidth
;
437 if (line
->dx
>= 0.0) {
438 xLeft
= x0
- 3.0F
* line
->halfWidth
;
439 xRight
= x0
+ line
->halfWidth
;
442 xLeft
= x0
- line
->halfWidth
;
443 xRight
= x0
+ 3.0F
* line
->halfWidth
;
447 yBot
= y1
- line
->halfWidth
;
448 yTop
= y0
+ line
->halfWidth
;
449 if (line
->dx
<= 0.0) {
450 xLeft
= x1
- 3.0F
* line
->halfWidth
;
451 xRight
= x1
+ line
->halfWidth
;
454 xLeft
= x1
- line
->halfWidth
;
455 xRight
= x1
+ 3.0F
* line
->halfWidth
;
459 /* scan along the line, bottom-to-top */
460 iyTop
= (GLint
) (yTop
+ 1.0F
);
462 /*printf("avg span width: %g\n", xRight - xLeft);*/
463 for (iy
= (GLint
) yBot
; iy
< iyTop
; iy
++) {
464 const GLint ixLeft
= (GLint
) xLeft
;
465 const GLint ixRight
= (GLint
) (xRight
+ 1.0F
);
467 /* scan across the line, left-to-right */
468 for (ix
= ixLeft
; ix
< ixRight
; ix
++) {
469 (*plot
)(ctx
, line
, ix
, iy
);
478 #define NAME(x) aa_ci_##x
480 #define DO_ATTRIBS /* for fog */
482 #include "s_aalinetemp.h"
485 #define NAME(x) aa_rgba_##x
488 #include "s_aalinetemp.h"
491 #define NAME(x) aa_general_rgba_##x
495 #include "s_aalinetemp.h"
500 _swrast_choose_aa_line_function(GLcontext
*ctx
)
502 SWcontext
*swrast
= SWRAST_CONTEXT(ctx
);
504 ASSERT(ctx
->Line
.SmoothFlag
);
506 if (ctx
->Visual
.rgbMode
) {
508 if (ctx
->Texture
._EnabledCoordUnits
!= 0
509 || ctx
->FragmentProgram
._Current
510 || (ctx
->Light
.Enabled
&&
511 ctx
->Light
.Model
.ColorControl
== GL_SEPARATE_SPECULAR_COLOR
)
512 || ctx
->Fog
.ColorSumEnabled
513 || swrast
->_FogEnabled
) {
514 swrast
->Line
= aa_general_rgba_line
;
517 swrast
->Line
= aa_rgba_line
;
522 swrast
->Line
= aa_ci_line
;