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Fix line clipping bug. New comments.

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Need to use a new prim_header for the post-clipped line.  Otherwise,
we were changing the header passed to us from the vb code.  That messed
up the vertex pointers for the next line primitive.
This commit is contained in:
Brian 2007-07-10 15:24:31 -06:00
parent 985e37eedb
commit a49a23efc5
1 changed files with 23 additions and 16 deletions
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39
src/mesa/pipe/draw/draw_clip.c
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@ -69,7 +69,7 @@ static void interp_attr( GLfloat *fdst,
/* Interpolate between two vertices to produce a third.
*/
static void interp( struct clipper *clip,
static void interp( const struct clipper *clip,
struct vertex_header *dst,
GLfloat t,
const struct vertex_header *out,
@ -98,9 +98,7 @@ static void interp( struct clipper *clip,
const GLfloat *pos = dst->clip;
const GLfloat *scale = clip->stage.draw->viewport.scale;
const GLfloat *trans = clip->stage.draw->viewport.translate;
GLfloat oow;
oow = 1.0 / pos[3];
const GLfloat oow = 1.0 / pos[3];
dst->data[0][0] = pos[0] * oow * scale[0] + trans[0];
dst->data[0][1] = pos[1] * oow * scale[1] + trans[1];
@ -110,6 +108,9 @@ static void interp( struct clipper *clip,
/* Other attributes
* Note: start at 1 to skip winpos (data[0]) and subtract one
* since there's two vertex attrib slots we want to ignore (the header
* and the clippos.
*/
for (j = 1; j < nr_attrs-1; j++) {
interp_attr(dst->data[j], t, in->data[j], out->data[j]);
@ -295,13 +296,14 @@ do_clip_line( struct prim_stage *stage,
struct prim_header *header,
GLuint clipmask )
{
struct clipper *clipper = clipper_stage( stage );
const struct clipper *clipper = clipper_stage( stage );
struct vertex_header *v0 = header->v[0];
struct vertex_header *v1 = header->v[1];
const GLfloat *pos0 = v0->clip;
const GLfloat *pos1 = v1->clip;
GLfloat t0 = 0;
GLfloat t1 = 0;
struct prim_header newprim;
/* XXX: Note stupid hack to deal with tnl's 8-bit clipmask. Remove
* this once we correctly use 16bit masks for userclip planes.
@ -313,43 +315,47 @@ do_clip_line( struct prim_stage *stage,
}
while (clipmask) {
GLuint plane_idx = ffs(clipmask)-1;
const GLuint plane_idx = ffs(clipmask)-1;
const GLfloat *plane = clipper->plane[plane_idx];
clipmask &= ~(1<<plane_idx);
const GLfloat dp0 = dot4( pos0, plane );
const GLfloat dp1 = dot4( pos1, plane );
if (dp1 < 0) {
GLfloat t = dp1 / (dp1 - dp0);
if (t > t1) t1 = t;
t1 = MIN2(t1, t);
}
if (dp0 < 0) {
GLfloat t = dp0 / (dp0 - dp1);
if (t > t0) t0 = t;
t0 = MIN2(t0, t);
}
if (t0 + t1 >= 1.0)
return; /* discard */
clipmask &= ~(1 << plane_idx); /* turn off this plane's bit */
}
if (v0->clipmask) {
interp( clipper, stage->tmp[0], t0, v0, v1 );
header->v[0] = stage->tmp[0];
newprim.v[0] = stage->tmp[0];
}
else {
newprim.v[0] = v0;
}
if (v1->clipmask) {
interp( clipper, stage->tmp[1], t1, v1, v0 );
header->v[1] = stage->tmp[1];
newprim.v[1] = stage->tmp[1];
}
else {
newprim.v[1] = v1;
}
stage->next->line( stage->next, header );
stage->next->line( stage->next, &newprim );
}
static void clip_begin( struct prim_stage *stage )
{
struct clipper *clipper = clipper_stage(stage);
@ -361,7 +367,8 @@ static void clip_begin( struct prim_stage *stage )
stage->next->begin( stage->next );
}
static void
clip_point( struct prim_stage *stage,
struct prim_header *header )