mirror of
https://gitlab.freedesktop.org/cairo/cairo.git
synced 2026-05-05 04:08:13 +02:00
Cleaned up polygon tessellation code. Fixes all known problems.
This commit is contained in:
Carl Worth
parent
546b33d362
commit
d334c8bf8f
4 changed files with 136 additions and 108 deletions
|
|
@ -100,13 +100,10 @@ typedef struct _XrPath {
|
|||
} XrPath;
|
||||
|
||||
typedef struct _XrEdge {
|
||||
/* Externally initialized */
|
||||
XLineFixed edge;
|
||||
Bool clockWise;
|
||||
|
||||
/* Internal use by XrTrapsTessellateEdges */
|
||||
XFixed current_x;
|
||||
XFixed next_x;
|
||||
struct _XrEdge *next, *prev;
|
||||
} XrEdge;
|
||||
|
||||
|
|
|
|||
119
src/xrtraps.c
119
src/xrtraps.c
|
|
@ -43,10 +43,10 @@ _XrTrapsAddTrapFromPoints(XrTraps *traps, XFixed top, XFixed bottom,
|
|||
XPointFixed right_p1, XPointFixed right_p2);
|
||||
|
||||
static int
|
||||
_ComparePointFixedByY (const void *v1, const void *v2);
|
||||
_ComparePointFixedByY (const void *av, const void *bv);
|
||||
|
||||
static int
|
||||
_CompareXrEdgeByTop (const void *v1, const void *v2);
|
||||
_CompareXrEdgeByTop (const void *av, const void *bv);
|
||||
|
||||
static XFixed
|
||||
_ComputeX (XLineFixed *line, XFixed y);
|
||||
|
|
@ -150,13 +150,13 @@ _XrTrapsGrowBy(XrTraps *traps, int additional)
|
|||
}
|
||||
|
||||
static int
|
||||
_ComparePointFixedByY (const void *v1, const void *v2)
|
||||
_ComparePointFixedByY (const void *av, const void *bv)
|
||||
{
|
||||
const XPointFixed *p1 = v1, *p2 = v2;
|
||||
const XPointFixed *a = av, *b = bv;
|
||||
|
||||
int ret = p1->y - p2->y;
|
||||
int ret = a->y - b->y;
|
||||
if (ret == 0) {
|
||||
ret = p1->x - p2->x;
|
||||
ret = a->x - b->x;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
|
@ -194,14 +194,44 @@ XrTrapsTessellateRectangle (XrTraps *traps, XPointFixed q[4])
|
|||
}
|
||||
|
||||
static int
|
||||
_CompareXrEdgeByTop (const void *v1, const void *v2)
|
||||
_CompareXrEdgeByTop (const void *av, const void *bv)
|
||||
{
|
||||
const XrEdge *e1 = v1, *e2 = v2;
|
||||
const XrEdge *a = av, *b = bv;
|
||||
int ret;
|
||||
|
||||
ret = e1->edge.p1.y - e2->edge.p1.y;
|
||||
ret = a->edge.p1.y - b->edge.p1.y;
|
||||
if (ret == 0)
|
||||
ret = e1->edge.p1.x - e2->edge.p1.x;
|
||||
ret = a->edge.p1.x - b->edge.p1.x;
|
||||
return ret;
|
||||
}
|
||||
|
||||
/* Return value is:
|
||||
> 0 if a is "clockwise" from b, (in a mathematical, not a graphical sense)
|
||||
== 0 if slope(a) == slope(b)
|
||||
< 0 if a is "counter-clockwise" from b
|
||||
*/
|
||||
static int
|
||||
_CompareXrEdgeBySlope (const void *av, const void *bv)
|
||||
{
|
||||
const XrEdge *a = av, *b = bv;
|
||||
|
||||
double a_dx = XFixedToDouble(a->edge.p2.x - a->edge.p1.x);
|
||||
double a_dy = XFixedToDouble(a->edge.p2.y - a->edge.p1.y);
|
||||
double b_dx = XFixedToDouble(b->edge.p2.x - b->edge.p1.x);
|
||||
double b_dy = XFixedToDouble(b->edge.p2.y - b->edge.p1.y);
|
||||
|
||||
return b_dy * a_dx - a_dy * b_dx;
|
||||
}
|
||||
|
||||
static int
|
||||
_CompareXrEdgeByCurrentXThenSlope (const void *av, const void *bv)
|
||||
{
|
||||
const XrEdge *a = av, *b = bv;
|
||||
int ret;
|
||||
|
||||
ret = a->current_x - b->current_x;
|
||||
if (ret == 0)
|
||||
ret = _CompareXrEdgeBySlope(a, b);
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
|
@ -261,9 +291,7 @@ _SortEdgeList(XrEdge **active)
|
|||
*/
|
||||
for (en = next; en; en = en->next)
|
||||
{
|
||||
if (en->current_x < e->current_x ||
|
||||
(en->current_x == e->current_x &&
|
||||
en->next_x < e->next_x))
|
||||
if (_CompareXrEdgeByCurrentXThenSlope(e, en) > 0)
|
||||
{
|
||||
/*
|
||||
* insert en before e
|
||||
|
|
@ -293,7 +321,6 @@ _SortEdgeList(XrEdge **active)
|
|||
}
|
||||
}
|
||||
|
||||
|
||||
XrError
|
||||
XrTrapsTessellatePolygon (XrTraps *traps,
|
||||
XrPolygon *poly,
|
||||
|
|
@ -302,7 +329,7 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
XrError err;
|
||||
int inactive;
|
||||
XrEdge *active;
|
||||
XrEdge *e, *en, *ep, *next;
|
||||
XrEdge *e, *en, *next;
|
||||
XFixed y, next_y, intersect;
|
||||
int in_out, num_edges = poly->num_edges;
|
||||
XrEdge *edges = poly->edges;
|
||||
|
|
@ -317,6 +344,10 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
inactive = 0;
|
||||
while (active || inactive < num_edges)
|
||||
{
|
||||
for (e = active; e; e = e->next) {
|
||||
e->current_x = _ComputeX (&e->edge, y);
|
||||
}
|
||||
|
||||
/* insert new active edges into list */
|
||||
while (inactive < num_edges)
|
||||
{
|
||||
|
|
@ -327,52 +358,43 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
inactive++;
|
||||
e->current_x = _ComputeX (&e->edge, y);
|
||||
|
||||
/* insert e at sorted position */
|
||||
for (en=active, ep=0; en; ep=en, en=en->next)
|
||||
{
|
||||
if (en->current_x > e->current_x)
|
||||
break;
|
||||
}
|
||||
e->next = en;
|
||||
e->prev = ep;
|
||||
if (ep)
|
||||
ep->next = e;
|
||||
else
|
||||
active = e;
|
||||
if (en)
|
||||
en->prev = e;
|
||||
/* insert e at head of list */
|
||||
e->next = active;
|
||||
e->prev = NULL;
|
||||
if (active)
|
||||
active->prev = e;
|
||||
active = e;
|
||||
}
|
||||
|
||||
_SortEdgeList(&active);
|
||||
|
||||
/* find next inflection point */
|
||||
next_y = active->edge.p2.y;
|
||||
for (e = active; e; e = en)
|
||||
{
|
||||
en = e->next;
|
||||
|
||||
if (e->edge.p2.y < next_y)
|
||||
next_y = e->edge.p2.y;
|
||||
en = e->next;
|
||||
/* check intersect */
|
||||
if (en && e->current_x != en->current_x)
|
||||
{
|
||||
intersect = _ComputeIntersect (&e->edge, &en->edge);
|
||||
/* make sure this point is below the actual intersection */
|
||||
intersect = intersect + 1;
|
||||
/* is intersection within both edges and between y/next_y */
|
||||
if (intersect <= e->edge.p2.y && intersect <= en->edge.p2.y
|
||||
&& intersect < next_y && intersect > y)
|
||||
next_y = intersect;
|
||||
if (intersect > y) {
|
||||
/* Need to guarantee that we get all the way past
|
||||
the intersection point so that the edges sort
|
||||
properly next time through the loop. */
|
||||
while (_ComputeX(&e->edge, intersect) < _ComputeX(&en->edge, intersect))
|
||||
intersect++;
|
||||
if (intersect < next_y)
|
||||
next_y = intersect;
|
||||
}
|
||||
}
|
||||
}
|
||||
/* check next inactive point */
|
||||
if (inactive < num_edges && edges[inactive].edge.p1.y < next_y)
|
||||
next_y = edges[inactive].edge.p1.y;
|
||||
|
||||
/* compute x coordinates along this group */
|
||||
for (e = active; e; e = e->next) {
|
||||
e->next_x = _ComputeX (&e->edge, next_y);
|
||||
}
|
||||
|
||||
_SortEdgeList(&active);
|
||||
|
||||
#if 0
|
||||
printf ("y: %6.3g:", y / 65536.0);
|
||||
for (e = active; e; e = e->next)
|
||||
|
|
@ -406,18 +428,11 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
return err;
|
||||
}
|
||||
|
||||
y = next_y;
|
||||
for (e = active; e; e = e->next) {
|
||||
e->current_x = e->next_x;
|
||||
}
|
||||
|
||||
_SortEdgeList(&active);
|
||||
|
||||
/* delete inactive edges from list */
|
||||
for (e = active; e; e = next)
|
||||
{
|
||||
next = e->next;
|
||||
if (e->edge.p2.y <= y)
|
||||
if (e->edge.p2.y <= next_y)
|
||||
{
|
||||
if (e->prev)
|
||||
e->prev->next = e->next;
|
||||
|
|
@ -427,6 +442,8 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
e->next->prev = e->prev;
|
||||
}
|
||||
}
|
||||
|
||||
y = next_y;
|
||||
}
|
||||
return XrErrorSuccess;
|
||||
}
|
||||
|
|
|
|||
3
xrint.h
3
xrint.h
|
|
@ -100,13 +100,10 @@ typedef struct _XrPath {
|
|||
} XrPath;
|
||||
|
||||
typedef struct _XrEdge {
|
||||
/* Externally initialized */
|
||||
XLineFixed edge;
|
||||
Bool clockWise;
|
||||
|
||||
/* Internal use by XrTrapsTessellateEdges */
|
||||
XFixed current_x;
|
||||
XFixed next_x;
|
||||
struct _XrEdge *next, *prev;
|
||||
} XrEdge;
|
||||
|
||||
|
|
|
|||
119
xrtraps.c
119
xrtraps.c
|
|
@ -43,10 +43,10 @@ _XrTrapsAddTrapFromPoints(XrTraps *traps, XFixed top, XFixed bottom,
|
|||
XPointFixed right_p1, XPointFixed right_p2);
|
||||
|
||||
static int
|
||||
_ComparePointFixedByY (const void *v1, const void *v2);
|
||||
_ComparePointFixedByY (const void *av, const void *bv);
|
||||
|
||||
static int
|
||||
_CompareXrEdgeByTop (const void *v1, const void *v2);
|
||||
_CompareXrEdgeByTop (const void *av, const void *bv);
|
||||
|
||||
static XFixed
|
||||
_ComputeX (XLineFixed *line, XFixed y);
|
||||
|
|
@ -150,13 +150,13 @@ _XrTrapsGrowBy(XrTraps *traps, int additional)
|
|||
}
|
||||
|
||||
static int
|
||||
_ComparePointFixedByY (const void *v1, const void *v2)
|
||||
_ComparePointFixedByY (const void *av, const void *bv)
|
||||
{
|
||||
const XPointFixed *p1 = v1, *p2 = v2;
|
||||
const XPointFixed *a = av, *b = bv;
|
||||
|
||||
int ret = p1->y - p2->y;
|
||||
int ret = a->y - b->y;
|
||||
if (ret == 0) {
|
||||
ret = p1->x - p2->x;
|
||||
ret = a->x - b->x;
|
||||
}
|
||||
return ret;
|
||||
}
|
||||
|
|
@ -194,14 +194,44 @@ XrTrapsTessellateRectangle (XrTraps *traps, XPointFixed q[4])
|
|||
}
|
||||
|
||||
static int
|
||||
_CompareXrEdgeByTop (const void *v1, const void *v2)
|
||||
_CompareXrEdgeByTop (const void *av, const void *bv)
|
||||
{
|
||||
const XrEdge *e1 = v1, *e2 = v2;
|
||||
const XrEdge *a = av, *b = bv;
|
||||
int ret;
|
||||
|
||||
ret = e1->edge.p1.y - e2->edge.p1.y;
|
||||
ret = a->edge.p1.y - b->edge.p1.y;
|
||||
if (ret == 0)
|
||||
ret = e1->edge.p1.x - e2->edge.p1.x;
|
||||
ret = a->edge.p1.x - b->edge.p1.x;
|
||||
return ret;
|
||||
}
|
||||
|
||||
/* Return value is:
|
||||
> 0 if a is "clockwise" from b, (in a mathematical, not a graphical sense)
|
||||
== 0 if slope(a) == slope(b)
|
||||
< 0 if a is "counter-clockwise" from b
|
||||
*/
|
||||
static int
|
||||
_CompareXrEdgeBySlope (const void *av, const void *bv)
|
||||
{
|
||||
const XrEdge *a = av, *b = bv;
|
||||
|
||||
double a_dx = XFixedToDouble(a->edge.p2.x - a->edge.p1.x);
|
||||
double a_dy = XFixedToDouble(a->edge.p2.y - a->edge.p1.y);
|
||||
double b_dx = XFixedToDouble(b->edge.p2.x - b->edge.p1.x);
|
||||
double b_dy = XFixedToDouble(b->edge.p2.y - b->edge.p1.y);
|
||||
|
||||
return b_dy * a_dx - a_dy * b_dx;
|
||||
}
|
||||
|
||||
static int
|
||||
_CompareXrEdgeByCurrentXThenSlope (const void *av, const void *bv)
|
||||
{
|
||||
const XrEdge *a = av, *b = bv;
|
||||
int ret;
|
||||
|
||||
ret = a->current_x - b->current_x;
|
||||
if (ret == 0)
|
||||
ret = _CompareXrEdgeBySlope(a, b);
|
||||
return ret;
|
||||
}
|
||||
|
||||
|
|
@ -261,9 +291,7 @@ _SortEdgeList(XrEdge **active)
|
|||
*/
|
||||
for (en = next; en; en = en->next)
|
||||
{
|
||||
if (en->current_x < e->current_x ||
|
||||
(en->current_x == e->current_x &&
|
||||
en->next_x < e->next_x))
|
||||
if (_CompareXrEdgeByCurrentXThenSlope(e, en) > 0)
|
||||
{
|
||||
/*
|
||||
* insert en before e
|
||||
|
|
@ -293,7 +321,6 @@ _SortEdgeList(XrEdge **active)
|
|||
}
|
||||
}
|
||||
|
||||
|
||||
XrError
|
||||
XrTrapsTessellatePolygon (XrTraps *traps,
|
||||
XrPolygon *poly,
|
||||
|
|
@ -302,7 +329,7 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
XrError err;
|
||||
int inactive;
|
||||
XrEdge *active;
|
||||
XrEdge *e, *en, *ep, *next;
|
||||
XrEdge *e, *en, *next;
|
||||
XFixed y, next_y, intersect;
|
||||
int in_out, num_edges = poly->num_edges;
|
||||
XrEdge *edges = poly->edges;
|
||||
|
|
@ -317,6 +344,10 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
inactive = 0;
|
||||
while (active || inactive < num_edges)
|
||||
{
|
||||
for (e = active; e; e = e->next) {
|
||||
e->current_x = _ComputeX (&e->edge, y);
|
||||
}
|
||||
|
||||
/* insert new active edges into list */
|
||||
while (inactive < num_edges)
|
||||
{
|
||||
|
|
@ -327,52 +358,43 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
inactive++;
|
||||
e->current_x = _ComputeX (&e->edge, y);
|
||||
|
||||
/* insert e at sorted position */
|
||||
for (en=active, ep=0; en; ep=en, en=en->next)
|
||||
{
|
||||
if (en->current_x > e->current_x)
|
||||
break;
|
||||
}
|
||||
e->next = en;
|
||||
e->prev = ep;
|
||||
if (ep)
|
||||
ep->next = e;
|
||||
else
|
||||
active = e;
|
||||
if (en)
|
||||
en->prev = e;
|
||||
/* insert e at head of list */
|
||||
e->next = active;
|
||||
e->prev = NULL;
|
||||
if (active)
|
||||
active->prev = e;
|
||||
active = e;
|
||||
}
|
||||
|
||||
_SortEdgeList(&active);
|
||||
|
||||
/* find next inflection point */
|
||||
next_y = active->edge.p2.y;
|
||||
for (e = active; e; e = en)
|
||||
{
|
||||
en = e->next;
|
||||
|
||||
if (e->edge.p2.y < next_y)
|
||||
next_y = e->edge.p2.y;
|
||||
en = e->next;
|
||||
/* check intersect */
|
||||
if (en && e->current_x != en->current_x)
|
||||
{
|
||||
intersect = _ComputeIntersect (&e->edge, &en->edge);
|
||||
/* make sure this point is below the actual intersection */
|
||||
intersect = intersect + 1;
|
||||
/* is intersection within both edges and between y/next_y */
|
||||
if (intersect <= e->edge.p2.y && intersect <= en->edge.p2.y
|
||||
&& intersect < next_y && intersect > y)
|
||||
next_y = intersect;
|
||||
if (intersect > y) {
|
||||
/* Need to guarantee that we get all the way past
|
||||
the intersection point so that the edges sort
|
||||
properly next time through the loop. */
|
||||
while (_ComputeX(&e->edge, intersect) < _ComputeX(&en->edge, intersect))
|
||||
intersect++;
|
||||
if (intersect < next_y)
|
||||
next_y = intersect;
|
||||
}
|
||||
}
|
||||
}
|
||||
/* check next inactive point */
|
||||
if (inactive < num_edges && edges[inactive].edge.p1.y < next_y)
|
||||
next_y = edges[inactive].edge.p1.y;
|
||||
|
||||
/* compute x coordinates along this group */
|
||||
for (e = active; e; e = e->next) {
|
||||
e->next_x = _ComputeX (&e->edge, next_y);
|
||||
}
|
||||
|
||||
_SortEdgeList(&active);
|
||||
|
||||
#if 0
|
||||
printf ("y: %6.3g:", y / 65536.0);
|
||||
for (e = active; e; e = e->next)
|
||||
|
|
@ -406,18 +428,11 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
return err;
|
||||
}
|
||||
|
||||
y = next_y;
|
||||
for (e = active; e; e = e->next) {
|
||||
e->current_x = e->next_x;
|
||||
}
|
||||
|
||||
_SortEdgeList(&active);
|
||||
|
||||
/* delete inactive edges from list */
|
||||
for (e = active; e; e = next)
|
||||
{
|
||||
next = e->next;
|
||||
if (e->edge.p2.y <= y)
|
||||
if (e->edge.p2.y <= next_y)
|
||||
{
|
||||
if (e->prev)
|
||||
e->prev->next = e->next;
|
||||
|
|
@ -427,6 +442,8 @@ XrTrapsTessellatePolygon (XrTraps *traps,
|
|||
e->next->prev = e->prev;
|
||||
}
|
||||
}
|
||||
|
||||
y = next_y;
|
||||
}
|
||||
return XrErrorSuccess;
|
||||
}
|
||||
|
|
|
|||
Loading…
Add table
Reference in a new issue