2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2003 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.
27 * Antialiased Triangle rasterizers
37 #include "nvfragprog.h"
38 #include "s_aatriangle.h"
39 #include "s_context.h"
44 * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2
45 * vertices and the given Z values.
46 * A point (x,y,z) lies on plane iff a*x+b*y+c*z+d = 0.
49 compute_plane(const GLfloat v0
[], const GLfloat v1
[], const GLfloat v2
[],
50 GLfloat z0
, GLfloat z1
, GLfloat z2
, GLfloat plane
[4])
52 const GLfloat px
= v1
[0] - v0
[0];
53 const GLfloat py
= v1
[1] - v0
[1];
54 const GLfloat pz
= z1
- z0
;
56 const GLfloat qx
= v2
[0] - v0
[0];
57 const GLfloat qy
= v2
[1] - v0
[1];
58 const GLfloat qz
= z2
- z0
;
60 /* Crossproduct "(a,b,c):= dv1 x dv2" is orthogonal to plane. */
61 const GLfloat a
= py
* qz
- pz
* qy
;
62 const GLfloat b
= pz
* qx
- px
* qz
;
63 const GLfloat c
= px
* qy
- py
* qx
;
64 /* Point on the plane = "r*(a,b,c) + w", with fixed "r" depending
65 on the distance of plane from origin and arbitrary "w" parallel
67 /* The scalar product "(r*(a,b,c)+w)*(a,b,c)" is "r*(a^2+b^2+c^2)",
68 which is equal to "-d" below. */
69 const GLfloat d
= -(a
* v0
[0] + b
* v0
[1] + c
* z0
);
79 * Compute coefficients of a plane with a constant Z value.
82 constant_plane(GLfloat value
, GLfloat plane
[4])
90 #define CONSTANT_PLANE(VALUE, PLANE) \
101 * Solve plane equation for Z at (X,Y).
103 static INLINE GLfloat
104 solve_plane(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
106 ASSERT(plane
[2] != 0.0F
);
107 return (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
111 #define SOLVE_PLANE(X, Y, PLANE) \
112 ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
116 * Return 1 / solve_plane().
118 static INLINE GLfloat
119 solve_plane_recip(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
121 const GLfloat denom
= plane
[3] + plane
[0] * x
+ plane
[1] * y
;
125 return -plane
[2] / denom
;
130 * Solve plane and return clamped GLchan value.
133 solve_plane_chan(GLfloat x
, GLfloat y
, const GLfloat plane
[4])
135 const GLfloat z
= (plane
[3] + plane
[0] * x
+ plane
[1] * y
) / -plane
[2];
136 #if CHAN_TYPE == GL_FLOAT
137 return CLAMP(z
, 0.0F
, CHAN_MAXF
);
141 else if (z
> CHAN_MAX
)
143 return (GLchan
) IROUND_POS(z
);
150 * Compute how much (area) of the given pixel is inside the triangle.
151 * Vertices MUST be specified in counter-clockwise order.
152 * Return: coverage in [0, 1].
155 compute_coveragef(const GLfloat v0
[3], const GLfloat v1
[3],
156 const GLfloat v2
[3], GLint winx
, GLint winy
)
158 /* Given a position [0,3]x[0,3] return the sub-pixel sample position.
159 * Contributed by Ray Tice.
161 * Jitter sample positions -
162 * - average should be .5 in x & y for each column
163 * - each of the 16 rows and columns should be used once
164 * - the rectangle formed by the first four points
165 * should contain the other points
166 * - the distrubition should be fairly even in any given direction
168 * The pattern drawn below isn't optimal, but it's better than a regular
169 * grid. In the drawing, the center of each subpixel is surrounded by
170 * four dots. The "x" marks the jittered position relative to the
173 #define POS(a, b) (0.5+a*4+b)/16
174 static const GLfloat samples
[16][2] = {
175 /* start with the four corners */
176 { POS(0, 2), POS(0, 0) },
177 { POS(3, 3), POS(0, 2) },
178 { POS(0, 0), POS(3, 1) },
179 { POS(3, 1), POS(3, 3) },
180 /* continue with interior samples */
181 { POS(1, 1), POS(0, 1) },
182 { POS(2, 0), POS(0, 3) },
183 { POS(0, 3), POS(1, 3) },
184 { POS(1, 2), POS(1, 0) },
185 { POS(2, 3), POS(1, 2) },
186 { POS(3, 2), POS(1, 1) },
187 { POS(0, 1), POS(2, 2) },
188 { POS(1, 0), POS(2, 1) },
189 { POS(2, 1), POS(2, 3) },
190 { POS(3, 0), POS(2, 0) },
191 { POS(1, 3), POS(3, 0) },
192 { POS(2, 2), POS(3, 2) }
195 const GLfloat x
= (GLfloat
) winx
;
196 const GLfloat y
= (GLfloat
) winy
;
197 const GLfloat dx0
= v1
[0] - v0
[0];
198 const GLfloat dy0
= v1
[1] - v0
[1];
199 const GLfloat dx1
= v2
[0] - v1
[0];
200 const GLfloat dy1
= v2
[1] - v1
[1];
201 const GLfloat dx2
= v0
[0] - v2
[0];
202 const GLfloat dy2
= v0
[1] - v2
[1];
204 GLfloat insideCount
= 16.0F
;
208 const GLfloat area
= dx0
* dy1
- dx1
* dy0
;
213 for (i
= 0; i
< stop
; i
++) {
214 const GLfloat sx
= x
+ samples
[i
][0];
215 const GLfloat sy
= y
+ samples
[i
][1];
216 /* cross product determines if sample is inside or outside each edge */
217 GLfloat cross
= (dx0
* (sy
- v0
[1]) - dy0
* (sx
- v0
[0]));
218 /* Check if the sample is exactly on an edge. If so, let cross be a
219 * positive or negative value depending on the direction of the edge.
224 /* sample point is outside first edge */
229 /* sample point is inside first edge */
230 cross
= (dx1
* (sy
- v1
[1]) - dy1
* (sx
- v1
[0]));
234 /* sample point is outside second edge */
239 /* sample point is inside first and second edges */
240 cross
= (dx2
* (sy
- v2
[1]) - dy2
* (sx
- v2
[0]));
244 /* sample point is outside third edge */
254 return insideCount
* (1.0F
/ 16.0F
);
260 * Compute how much (area) of the given pixel is inside the triangle.
261 * Vertices MUST be specified in counter-clockwise order.
262 * Return: coverage in [0, 15].
265 compute_coveragei(const GLfloat v0
[3], const GLfloat v1
[3],
266 const GLfloat v2
[3], GLint winx
, GLint winy
)
268 /* NOTE: 15 samples instead of 16. */
269 static const GLfloat samples
[15][2] = {
270 /* start with the four corners */
271 { POS(0, 2), POS(0, 0) },
272 { POS(3, 3), POS(0, 2) },
273 { POS(0, 0), POS(3, 1) },
274 { POS(3, 1), POS(3, 3) },
275 /* continue with interior samples */
276 { POS(1, 1), POS(0, 1) },
277 { POS(2, 0), POS(0, 3) },
278 { POS(0, 3), POS(1, 3) },
279 { POS(1, 2), POS(1, 0) },
280 { POS(2, 3), POS(1, 2) },
281 { POS(3, 2), POS(1, 1) },
282 { POS(0, 1), POS(2, 2) },
283 { POS(1, 0), POS(2, 1) },
284 { POS(2, 1), POS(2, 3) },
285 { POS(3, 0), POS(2, 0) },
286 { POS(1, 3), POS(3, 0) }
288 const GLfloat x
= (GLfloat
) winx
;
289 const GLfloat y
= (GLfloat
) winy
;
290 const GLfloat dx0
= v1
[0] - v0
[0];
291 const GLfloat dy0
= v1
[1] - v0
[1];
292 const GLfloat dx1
= v2
[0] - v1
[0];
293 const GLfloat dy1
= v2
[1] - v1
[1];
294 const GLfloat dx2
= v0
[0] - v2
[0];
295 const GLfloat dy2
= v0
[1] - v2
[1];
297 GLint insideCount
= 15;
301 const GLfloat area
= dx0
* dy1
- dx1
* dy0
;
306 for (i
= 0; i
< stop
; i
++) {
307 const GLfloat sx
= x
+ samples
[i
][0];
308 const GLfloat sy
= y
+ samples
[i
][1];
309 const GLfloat fx0
= sx
- v0
[0];
310 const GLfloat fy0
= sy
- v0
[1];
311 const GLfloat fx1
= sx
- v1
[0];
312 const GLfloat fy1
= sy
- v1
[1];
313 const GLfloat fx2
= sx
- v2
[0];
314 const GLfloat fy2
= sy
- v2
[1];
315 /* cross product determines if sample is inside or outside each edge */
316 GLfloat cross0
= (dx0
* fy0
- dy0
* fx0
);
317 GLfloat cross1
= (dx1
* fy1
- dy1
* fx1
);
318 GLfloat cross2
= (dx2
* fy2
- dy2
* fx2
);
319 /* Check if the sample is exactly on an edge. If so, let cross be a
320 * positive or negative value depending on the direction of the edge.
328 if (cross0
< 0.0F
|| cross1
< 0.0F
|| cross2
< 0.0F
) {
329 /* point is outside triangle */
343 rgba_aa_tri(GLcontext
*ctx
,
351 #include "s_aatritemp.h"
356 index_aa_tri(GLcontext
*ctx
,
364 #include "s_aatritemp.h"
369 * Compute mipmap level of detail.
370 * XXX we should really include the R coordinate in this computation
371 * in order to do 3-D texture mipmapping.
373 static INLINE GLfloat
374 compute_lambda(const GLfloat sPlane
[4], const GLfloat tPlane
[4],
375 const GLfloat qPlane
[4], GLfloat cx
, GLfloat cy
,
376 GLfloat invQ
, GLfloat texWidth
, GLfloat texHeight
)
378 const GLfloat s
= solve_plane(cx
, cy
, sPlane
);
379 const GLfloat t
= solve_plane(cx
, cy
, tPlane
);
380 const GLfloat invQ_x1
= solve_plane_recip(cx
+1.0F
, cy
, qPlane
);
381 const GLfloat invQ_y1
= solve_plane_recip(cx
, cy
+1.0F
, qPlane
);
382 const GLfloat s_x1
= s
- sPlane
[0] / sPlane
[2];
383 const GLfloat s_y1
= s
- sPlane
[1] / sPlane
[2];
384 const GLfloat t_x1
= t
- tPlane
[0] / tPlane
[2];
385 const GLfloat t_y1
= t
- tPlane
[1] / tPlane
[2];
386 GLfloat dsdx
= s_x1
* invQ_x1
- s
* invQ
;
387 GLfloat dsdy
= s_y1
* invQ_y1
- s
* invQ
;
388 GLfloat dtdx
= t_x1
* invQ_x1
- t
* invQ
;
389 GLfloat dtdy
= t_y1
* invQ_y1
- t
* invQ
;
390 GLfloat maxU
, maxV
, rho
, lambda
;
395 maxU
= MAX2(dsdx
, dsdy
) * texWidth
;
396 maxV
= MAX2(dtdx
, dtdy
) * texHeight
;
397 rho
= MAX2(maxU
, maxV
);
404 tex_aa_tri(GLcontext
*ctx
,
413 #include "s_aatritemp.h"
418 spec_tex_aa_tri(GLcontext
*ctx
,
428 #include "s_aatritemp.h"
433 multitex_aa_tri(GLcontext
*ctx
,
442 #include "s_aatritemp.h"
446 spec_multitex_aa_tri(GLcontext
*ctx
,
456 #include "s_aatritemp.h"
461 * Examine GL state and set swrast->Triangle to an
462 * appropriate antialiased triangle rasterizer function.
465 _swrast_set_aa_triangle_function(GLcontext
*ctx
)
467 ASSERT(ctx
->Polygon
.SmoothFlag
);
469 if (ctx
->Texture
._EnabledCoordUnits
!= 0) {
470 if (NEED_SECONDARY_COLOR(ctx
)) {
471 if (ctx
->Texture
._EnabledCoordUnits
> 1) {
472 SWRAST_CONTEXT(ctx
)->Triangle
= spec_multitex_aa_tri
;
475 SWRAST_CONTEXT(ctx
)->Triangle
= spec_tex_aa_tri
;
479 if (ctx
->Texture
._EnabledCoordUnits
> 1) {
480 SWRAST_CONTEXT(ctx
)->Triangle
= multitex_aa_tri
;
483 SWRAST_CONTEXT(ctx
)->Triangle
= tex_aa_tri
;
487 else if (ctx
->Visual
.rgbMode
) {
488 SWRAST_CONTEXT(ctx
)->Triangle
= rgba_aa_tri
;
491 SWRAST_CONTEXT(ctx
)->Triangle
= index_aa_tri
;
494 ASSERT(SWRAST_CONTEXT(ctx
)->Triangle
);