/* Clip a triangle against the viewport and user clip planes.
*/
static void
do_clip_tri( struct draw_stage *stage,
struct prim_header *header,
unsigned clipmask )
{
struct clip_stage *clipper = clip_stage( stage );
struct vertex_header *a[MAX_CLIPPED_VERTICES];
struct vertex_header *b[MAX_CLIPPED_VERTICES];
struct vertex_header **inlist = a;
struct vertex_header **outlist = b;
unsigned tmpnr = 0;
unsigned n = 3;
unsigned i;
boolean aEdges[MAX_CLIPPED_VERTICES];
boolean bEdges[MAX_CLIPPED_VERTICES];
boolean *inEdges = aEdges;
boolean *outEdges = bEdges;
inlist[0] = header->v[0];
inlist[1] = header->v[1];
inlist[2] = header->v[2];
/*
* Note: at this point we can't just use the per-vertex edge flags.
* We have to observe the edge flag bits set in header->flags which
* were set during primitive decomposition. Put those flags into
* an edge flags array which parallels the vertex array.
* Later, in the 'unfilled' pipeline stage we'll draw the edge if both
* the header.flags bit is set AND the per-vertex edgeflag field is set.
*/
inEdges[0] = !!(header->flags & DRAW_PIPE_EDGE_FLAG_0);
inEdges[1] = !!(header->flags & DRAW_PIPE_EDGE_FLAG_1);
inEdges[2] = !!(header->flags & DRAW_PIPE_EDGE_FLAG_2);
while (clipmask && n >= 3) {
const unsigned plane_idx = ffs(clipmask)-1;
const boolean is_user_clip_plane = plane_idx >= 6;
const float *plane = clipper->plane[plane_idx];
struct vertex_header *vert_prev = inlist[0];
boolean *edge_prev = &inEdges[0];
float dp_prev = dot4( vert_prev->clip, plane );
unsigned outcount = 0;
clipmask &= ~(1<<plane_idx);
assert(n < MAX_CLIPPED_VERTICES);
if (n >= MAX_CLIPPED_VERTICES)
return;
inlist[n] = inlist[0]; /* prevent rotation of vertices */
inEdges[n] = inEdges[0];
for (i = 1; i <= n; i++) {
struct vertex_header *vert = inlist[i];
boolean *edge = &inEdges[i];
float dp = dot4( vert->clip, plane );
if (!IS_NEGATIVE(dp_prev)) {
assert(outcount < MAX_CLIPPED_VERTICES);
if (outcount >= MAX_CLIPPED_VERTICES)
return;
outEdges[outcount] = *edge_prev;
outlist[outcount++] = vert_prev;
}
if (DIFFERENT_SIGNS(dp, dp_prev)) {
struct vertex_header *new_vert;
boolean *new_edge;
assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
return;
new_vert = clipper->stage.tmp[tmpnr++];
assert(outcount < MAX_CLIPPED_VERTICES);
if (outcount >= MAX_CLIPPED_VERTICES)
return;
new_edge = &outEdges[outcount];
outlist[outcount++] = new_vert;
if (IS_NEGATIVE(dp)) {
/* Going out of bounds. Avoid division by zero as we
* know dp != dp_prev from DIFFERENT_SIGNS, above.
*/
float t = dp / (dp - dp_prev);
interp( clipper, new_vert, t, vert, vert_prev );
/* Whether or not to set edge flag for the new vert depends
* on whether it's a user-defined clipping plane. We're
* copying NVIDIA's behaviour here.
*/
if (is_user_clip_plane) {
/* we want to see an edge along the clip plane */
*new_edge = TRUE;
new_vert->edgeflag = TRUE;
}
else {
/* we don't want to see an edge along the frustum clip plane */
*new_edge = *edge_prev;
new_vert->edgeflag = FALSE;
}
}
else {
/* Coming back in.
*/
float t = dp_prev / (dp_prev - dp);
interp( clipper, new_vert, t, vert_prev, vert );
/* Copy starting vert's edgeflag:
*/
new_vert->edgeflag = vert_prev->edgeflag;
*new_edge = *edge_prev;
}
}
vert_prev = vert;
edge_prev = edge;
dp_prev = dp;
}
/* swap in/out lists */
{
struct vertex_header **tmp = inlist;
inlist = outlist;
outlist = tmp;
n = outcount;
}
{
boolean *tmp = inEdges;
inEdges = outEdges;
outEdges = tmp;
}
}
/* If flat-shading, copy provoking vertex color to polygon vertex[0]
*/
if (n >= 3) {
if (clipper->flat) {
if (stage->draw->rasterizer->flatshade_first) {
if (inlist[0] != header->v[0]) {
assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
return;
inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
copy_colors(stage, inlist[0], header->v[0]);
}
}
else {
if (inlist[0] != header->v[2]) {
assert(tmpnr < MAX_CLIPPED_VERTICES + 1);
if (tmpnr >= MAX_CLIPPED_VERTICES + 1)
return;
inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
copy_colors(stage, inlist[0], header->v[2]);
}
}
}
/* Emit the polygon as triangles to the setup stage:
*/
emit_poly( stage, inlist, inEdges, n, header );
}
}
/* Clip a triangle against the viewport and user clip planes.
*/
static void
do_clip_tri( struct draw_stage *stage,
struct prim_header *header,
unsigned clipmask )
{
struct clipper *clipper = clipper_stage( stage );
struct vertex_header *a[MAX_CLIPPED_VERTICES];
struct vertex_header *b[MAX_CLIPPED_VERTICES];
struct vertex_header **inlist = a;
struct vertex_header **outlist = b;
unsigned tmpnr = 0;
unsigned n = 3;
unsigned i;
inlist[0] = header->v[0];
inlist[1] = header->v[1];
inlist[2] = header->v[2];
while (clipmask && n >= 3) {
const unsigned plane_idx = ffs(clipmask)-1;
const float *plane = clipper->plane[plane_idx];
struct vertex_header *vert_prev = inlist[0];
float dp_prev = dot4( vert_prev->clip, plane );
unsigned outcount = 0;
clipmask &= ~(1<<plane_idx);
inlist[n] = inlist[0]; /* prevent rotation of vertices */
for (i = 1; i <= n; i++) {
struct vertex_header *vert = inlist[i];
float dp = dot4( vert->clip, plane );
if (!IS_NEGATIVE(dp_prev)) {
outlist[outcount++] = vert_prev;
}
if (DIFFERENT_SIGNS(dp, dp_prev)) {
struct vertex_header *new_vert = clipper->stage.tmp[tmpnr++];
outlist[outcount++] = new_vert;
if (IS_NEGATIVE(dp)) {
/* Going out of bounds. Avoid division by zero as we
* know dp != dp_prev from DIFFERENT_SIGNS, above.
*/
float t = dp / (dp - dp_prev);
interp( clipper, new_vert, t, vert, vert_prev );
/* Force edgeflag true in this case:
*/
new_vert->edgeflag = 1;
} else {
/* Coming back in.
*/
float t = dp_prev / (dp_prev - dp);
interp( clipper, new_vert, t, vert_prev, vert );
/* Copy starting vert's edgeflag:
*/
new_vert->edgeflag = vert_prev->edgeflag;
}
}
vert_prev = vert;
dp_prev = dp;
}
{
struct vertex_header **tmp = inlist;
inlist = outlist;
outlist = tmp;
n = outcount;
}
}
/* If flat-shading, copy color to new provoking vertex.
*/
if (clipper->flat && inlist[0] != header->v[2]) {
if (1) {
inlist[0] = dup_vert(stage, inlist[0], tmpnr++);
}
copy_colors(stage, inlist[0], header->v[2]);
}
/* Emit the polygon as triangles to the setup stage:
*/
if (n >= 3)
emit_poly( stage, inlist, n, header );
}
