/**************************************************************************
*
* Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/**
* \brief Clipping stage
*
* \author Keith Whitwell <keith@tungstengraphics.com>
*/
#include "pipe/p_util.h"
#include "draw_context.h"
#include "draw_private.h"
#ifndef IS_NEGATIVE
#define IS_NEGATIVE(X) ((X) < 0.0)
#endif
#ifndef DIFFERENT_SIGNS
#define DIFFERENT_SIGNS(x, y) ((x) * (y) <= 0.0F && (x) - (y) != 0.0F)
#endif
#ifndef MAX_CLIPPED_VERTICES
#define MAX_CLIPPED_VERTICES ((2 * (6 + PIPE_MAX_CLIP_PLANES))+1)
#endif
struct clipper {
struct draw_stage stage; /**< base class */
float (*plane)[4];
};
/* This is a bit confusing:
*/
static INLINE struct clipper *clipper_stage( struct draw_stage *stage )
{
return (struct clipper *)stage;
}
#define LINTERP(T, OUT, IN) ((OUT) + (T) * ((IN) - (OUT)))
/* All attributes are float[4], so this is easy:
*/
static void interp_attr( float *fdst,
float t,
const float *fin,
const float *fout )
{
fdst[0] = LINTERP( t, fout[0], fin[0] );
fdst[1] = LINTERP( t, fout[1], fin[1] );
fdst[2] = LINTERP( t, fout[2], fin[2] );
fdst[3] = LINTERP( t, fout[3], fin[3] );
}
/* Interpolate between two vertices to produce a third.
*/
static void interp( const struct clipper *clip,
struct vertex_header *dst,
float t,
const struct vertex_header *out,
const struct vertex_header *in )
{
const unsigned nr_attrs = clip->stage.draw->num_vs_outputs;
unsigned j;
/* Vertex header.
*/
{
dst->clipmask = 0;
dst->edgeflag = 0;
dst->pad = 0;
dst->vertex_id = UNDEFINED_VERTEX_ID;
}
/* Clip coordinates: interpolate normally
*/
{
interp_attr(dst->clip, t, in->clip, out->clip);
}
/* Do the projective divide and insert window coordinates:
*/
{
const float *pos = dst->clip;
const float *scale = clip->stage.draw->viewport.scale;
const float *trans = clip->stage.draw->viewport.translate;
const float oow = 1.0f / pos[3];
dst->data[0][0] = pos[0] * oow * scale[0] + trans[0];
dst->data[0][1] = pos[1] * oow * scale[1] + trans[1];
dst->data[0][2] = pos[2] * oow * scale[2] + trans[2];
dst->data[0][3] = oow;
}
/* Other attributes
* Note: start at 1 to skip winpos (data[0]) since we just computed
* it above.
*/
for (j = 1; j < nr_attrs; j++) {
interp_attr(dst->data[j], t, in->data[j], out->data[j]);
}
}
#if 0
static INLINE void do_tri( struct draw_stage *next,
struct prim_header *header )
{
unsigned i;
for (i = 0; i < 3; i++) {
float *ndc = header->v[i]->data[0];
_mesa_printf("ndc %f %f %f\n", ndc[0], ndc[1], ndc[2]);
assert(ndc[0] >= -1 && ndc[0] <= 641);
assert(ndc[1] >= 30 && ndc[1] <= 481);
}
_mesa_printf("\n");
next->tri(next, header);
}
#endif
static void emit_poly( struct draw_stage *stage,
struct vertex_header **inlist,
unsigned n,
const struct prim_header *origPrim)
{
struct prim_header header;
unsigned i;
/* later stages may need the determinant, but only the sign matters */
header.det = origPrim->det;
for (i = 2; i < n; i++) {
header.v[0] = inlist[0];
header.v[1] = inlist[i-1];
header.v[2] = inlist[i];
{
unsigned tmp0 = header.v[0]->edgeflag;
unsigned tmp2 = header.v[2]->edgeflag;
if (i != 2) header.v[0]->edgeflag = 0;
if (i != n-1) header.v[2]->edgeflag = 0;
header.edgeflags = ((header.v[0]->edgeflag << 0) |
(header.v[1]->edgeflag << 1) |
(header.v[2]->edgeflag << 2));
stage->next->tri( stage->next, &header );
header.v[0]->edgeflag = tmp0;
header.v[2]->edgeflag = tmp2;
}
}
}
#if 0
static void emit_poly( struct draw_stage *stage )
{
unsigned i;
for (i = 2; i < n; i++) {
header->v[0] = inlist[0];
header->v[1] = inlist[i-1];
header->v[2] = inlist[i];
stage->next->tri( stage->next, header );
}
}
#endif
/* 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;
}
}
/* Emit the polygon as triangles to the setup stage:
*/
if (n >= 3)
emit_poly( stage, inlist, n, header );
}
/* Clip a line against the viewport and user clip planes.
*/
static void
do_clip_line( struct draw_stage *stage,
struct prim_header *header,
unsigned clipmask )
{
const struct clipper *clipper = clipper_stage( stage );
struct vertex_header *v0 = header->v[0];
struct vertex_header *v1 = header->v[1];
const float *pos0 = v0->clip;
const float *pos1 = v1->clip;
float t0 = 0.0F;
float t1 = 0.0F;
struct prim_header newprim;
while (clipmask) {
const unsigned plane_idx = ffs(clipmask)-1;
const float *plane = clipper->plane[plane_idx];
const float dp0 = dot4( pos0, plane );
const float dp1 = dot4( pos1, plane );
if (dp1 < 0.0F) {
float t = dp1 / (dp1 - dp0);
t1 = MAX2(t1, t);
}
if (dp0 < 0.0F) {
float t = dp0 / (dp0 - dp1);
t0 = MAX2(t0, t);
}
if (t0 + t1 >= 1.0F)
return; /* discard */
clipmask &= ~(1 << plane_idx); /* turn off this plane's bit */
}
if (v0->clipmask) {
interp( clipper, stage->tmp[0], t0, v0, v1 );
newprim.v[0] = stage->tmp[0];
}
else {
newprim.v[0] = v0;
}
if (v1->clipmask) {
interp( clipper, stage->tmp[1], t1, v1, v0 );
newprim.v[1] = stage->tmp[1];
}
else {
newprim.v[1] = v1;
}
stage->next->line( stage->next, &newprim );
}
static void
clip_point( struct draw_stage *stage,
struct prim_header *header )
{
if (header->v[0]->clipmask == 0)
stage->next->point( stage->next, header );
}
static void
clip_line( struct draw_stage *stage,
struct prim_header *header )
{
unsigned clipmask = (header->v[0]->clipmask |
header->v[1]->clipmask);
if (clipmask == 0) {
/* no clipping needed */
stage->next->line( stage->next, header );
}
else if ((header->v[0]->clipmask &
header->v[1]->clipmask) == 0) {
do_clip_line(stage, header, clipmask);
}
/* else, totally clipped */
}
static void
clip_tri( struct draw_stage *stage,
struct prim_header *header )
{
unsigned clipmask = (header->v[0]->clipmask |
header->v[1]->clipmask |
header->v[2]->clipmask);
if (clipmask == 0) {
/* no clipping needed */
stage->next->tri( stage->next, header );
}
else if ((header->v[0]->clipmask &
header->v[1]->clipmask &
header->v[2]->clipmask) == 0) {
do_clip_tri(stage, header, clipmask);
}
}
static void clip_flush( struct draw_stage *stage, unsigned flags )
{
stage->next->flush( stage->next, flags );
}
static void clip_reset_stipple_counter( struct draw_stage *stage )
{
stage->next->reset_stipple_counter( stage->next );
}
static void clip_destroy( struct draw_stage *stage )
{
draw_free_tmps( stage );
FREE( stage );
}
/**
* Allocate a new clipper stage.
* \return pointer to new stage object
*/
struct draw_stage *draw_clip_stage( struct draw_context *draw )
{
struct clipper *clipper = CALLOC_STRUCT(clipper);
draw_alloc_tmps( &clipper->stage, MAX_CLIPPED_VERTICES );
clipper->stage.draw = draw;
clipper->stage.point = clip_point;
clipper->stage.line = clip_line;
clipper->stage.tri = clip_tri;
clipper->stage.flush = clip_flush;
clipper->stage.reset_stipple_counter = clip_reset_stipple_counter;
clipper->stage.destroy = clip_destroy;
clipper->plane = draw->plane;
return &clipper->stage;
}