/**************************************************************************
*
* 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 "util/u_memory.h"
#include "util/u_math.h"
#include "pipe/p_shader_tokens.h"
#include "draw_vs.h"
#include "draw_pipe.h"
#include "draw_fs.h"
#include "draw_gs.h"
/** Set to 1 to enable printing of coords before/after clipping */
#define DEBUG_CLIP 0
#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
#define MAX_CLIPPED_VERTICES ((2 * (6 + PIPE_MAX_CLIP_PLANES))+1)
struct clip_stage {
struct draw_stage stage; /**< base class */
/* List of the attributes to be flatshaded. */
uint num_flat_attribs;
uint flat_attribs[PIPE_MAX_SHADER_OUTPUTS];
/* Mask of attributes in noperspective mode */
boolean noperspective_attribs[PIPE_MAX_SHADER_OUTPUTS];
float (*plane)[4];
};
/** Cast wrapper */
static INLINE struct clip_stage *clip_stage( struct draw_stage *stage )
{
return (struct clip_stage *)stage;
}
static INLINE unsigned
draw_viewport_index(struct draw_context *draw,
const struct vertex_header *leading_vertex)
{
if (draw_current_shader_uses_viewport_index(draw)) {
unsigned viewport_index_output =
draw_current_shader_viewport_index_output(draw);
unsigned viewport_index =
*((unsigned*)leading_vertex->data[viewport_index_output]);
return draw_clamp_viewport_idx(viewport_index);
} else {
return 0;
}
}
#define LINTERP(T, OUT, IN) ((OUT) + (T) * ((IN) - (OUT)))
/* All attributes are float[4], so this is easy:
*/
static void interp_attr( float dst[4],
float t,
const float in[4],
const float out[4] )
{
dst[0] = LINTERP( t, out[0], in[0] );
dst[1] = LINTERP( t, out[1], in[1] );
dst[2] = LINTERP( t, out[2], in[2] );
dst[3] = LINTERP( t, out[3], in[3] );
}
/**
* Copy flat shaded attributes src vertex to dst vertex.
*/
static void copy_flat( struct draw_stage *stage,
struct vertex_header *dst,
const struct vertex_header *src )
{
const struct clip_stage *clipper = clip_stage(stage);
uint i;
for (i = 0; i < clipper->num_flat_attribs; i++) {
const uint attr = clipper->flat_attribs[i];
COPY_4FV(dst->data[attr], src->data[attr]);
}
}
/* Interpolate between two vertices to produce a third.
*/
static void interp( const struct clip_stage *clip,
struct vertex_header *dst,
float t,
const struct vertex_header *out,
const struct vertex_header *in,
unsigned viewport_index )
{
const unsigned nr_attrs = draw_current_shader_outputs(clip->stage.draw);
const unsigned pos_attr = draw_current_shader_position_output(clip->stage.draw);
const unsigned clip_attr = draw_current_shader_clipvertex_output(clip->stage.draw);
unsigned j;
float t_nopersp;
/* Vertex header.
*/
dst->clipmask = 0;
dst->edgeflag = 0; /* will get overwritten later */
dst->have_clipdist = in->have_clipdist;
dst->vertex_id = UNDEFINED_VERTEX_ID;
/* Interpolate the clip-space coords.
*/
interp_attr(dst->clip, t, in->clip, out->clip);
/* interpolate the clip-space position */
interp_attr(dst->pre_clip_pos, t, in->pre_clip_pos, out->pre_clip_pos);
/* Do the projective divide and viewport transformation to get
* new window coordinates:
*/
{
const float *pos = dst->pre_clip_pos;
const float *scale =
clip->stage.draw->viewports[viewport_index].scale;
const float *trans =
clip->stage.draw->viewports[viewport_index].translate;
const float oow = 1.0f / pos[3];
dst->data[pos_attr][0] = pos[0] * oow * scale[0] + trans[0];
dst->data[pos_attr][1] = pos[1] * oow * scale[1] + trans[1];
dst->data[pos_attr][2] = pos[2] * oow * scale[2] + trans[2];
dst->data[pos_attr][3] = oow;
}
/**
* Compute the t in screen-space instead of 3d space to use
* for noperspective interpolation.
*
* The points can be aligned with the X axis, so in that case try
* the Y. When both points are at the same screen position, we can
* pick whatever value (the interpolated point won't be in front
* anyway), so just use the 3d t.
*/
{
int k;
t_nopersp = t;
/* find either in.x != out.x or in.y != out.y */
for (k = 0; k < 2; k++) {
if (in->clip[k] != out->clip[k]) {
/* do divide by W, then compute linear interpolation factor */
float in_coord = in->clip[k] / in->clip[3];
float out_coord = out->clip[k] / out->clip[3];
float dst_coord = dst->clip[k] / dst->clip[3];
t_nopersp = (dst_coord - out_coord) / (in_coord - out_coord);
break;
}
}
}
/* Other attributes
*/
for (j = 0; j < nr_attrs; j++) {
if (j != pos_attr && j != clip_attr) {
if (clip->noperspective_attribs[j])
interp_attr(dst->data[j], t_nopersp, in->data[j], out->data[j]);
else
interp_attr(dst->data[j], t, in->data[j], out->data[j]);
}
}
}
/**
* Emit a post-clip polygon to the next pipeline stage. The polygon
* will be convex and the provoking vertex will always be vertex[0].
*/
static void emit_poly( struct draw_stage *stage,
struct vertex_header **inlist,
const boolean *edgeflags,
unsigned n,
const struct prim_header *origPrim)
{
struct prim_header header;
unsigned i;
ushort edge_first, edge_middle, edge_last;
if (stage->draw->rasterizer->flatshade_first) {
edge_first = DRAW_PIPE_EDGE_FLAG_0;
edge_middle = DRAW_PIPE_EDGE_FLAG_1;
edge_last = DRAW_PIPE_EDGE_FLAG_2;
}
else {
edge_first = DRAW_PIPE_EDGE_FLAG_2;
edge_middle = DRAW_PIPE_EDGE_FLAG_0;
edge_last = DRAW_PIPE_EDGE_FLAG_1;
}
if (!edgeflags[0])
edge_first = 0;
/* later stages may need the determinant, but only the sign matters */
header.det = origPrim->det;
header.flags = DRAW_PIPE_RESET_STIPPLE | edge_first | edge_middle;
header.pad = 0;
for (i = 2; i < n; i++, header.flags = edge_middle) {
/* order the triangle verts to respect the provoking vertex mode */
if (stage->draw->rasterizer->flatshade_first) {
header.v[0] = inlist[0]; /* the provoking vertex */
header.v[1] = inlist[i-1];
header.v[2] = inlist[i];
}
else {
header.v[0] = inlist[i-1];
header.v[1] = inlist[i];
header.v[2] = inlist[0]; /* the provoking vertex */
}
if (!edgeflags[i-1]) {
header.flags &= ~edge_middle;
}
if (i == n - 1 && edgeflags[i])
header.flags |= edge_last;
if (DEBUG_CLIP) {
const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
uint j, k;
debug_printf("Clipped tri: (flat-shade-first = %d)\n",
stage->draw->rasterizer->flatshade_first);
for (j = 0; j < 3; j++) {
debug_printf(" Vert %d: clip: %f %f %f %f\n", j,
header.v[j]->clip[0],
header.v[j]->clip[1],
header.v[j]->clip[2],
header.v[j]->clip[3]);
for (k = 0; k < vs->info.num_outputs; k++) {
debug_printf(" Vert %d: Attr %d: %f %f %f %f\n", j, k,
header.v[j]->data[k][0],
header.v[j]->data[k][1],
header.v[j]->data[k][2],
header.v[j]->data[k][3]);
}
}
}
stage->next->tri( stage->next, &header );
}
}
static INLINE float
dot4(const float *a, const float *b)
{
return (a[0] * b[0] +
a[1] * b[1] +
a[2] * b[2] +
a[3] * b[3]);
}
/*
* this function extracts the clip distance for the current plane,
* it first checks if the shader provided a clip distance, otherwise
* it works out the value using the clipvertex
*/
static INLINE float getclipdist(const struct clip_stage *clipper,
struct vertex_header *vert,
int plane_idx)
{
const float *plane;
float dp;
if (vert->have_clipdist && plane_idx >= 6) {
/* pick the correct clipdistance element from the output vectors */
int _idx = plane_idx - 6;
int cdi = _idx >= 4;
int vidx = cdi ? _idx - 4 : _idx;
dp = vert->data[draw_current_shader_clipdistance_output(clipper->stage.draw, cdi)][vidx];
} else {
plane = clipper->plane[plane_idx];
dp = dot4(vert->clip, plane);
}
return dp;
}
/* 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;
int viewport_index = 0;
inlist[0] = header->v[0];
inlist[1] = header->v[1];
inlist[2] = header->v[2];
viewport_index = draw_viewport_index(clipper->stage.draw, inlist[0]);
if (DEBUG_CLIP) {
const float *v0 = header->v[0]->clip;
const float *v1 = header->v[1]->clip;
const float *v2 = header->v[2]->clip;
debug_printf("Clip triangle:\n");
debug_printf(" %f, %f, %f, %f\n", v0[0], v0[1], v0[2], v0[3]);
debug_printf(" %f, %f, %f, %f\n", v1[0], v1[1], v1[2], v1[3]);
debug_printf(" %f, %f, %f, %f\n", v2[0], v2[1], v2[2], v2[3]);
}
/*
* 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;
struct vertex_header *vert_prev = inlist[0];
boolean *edge_prev = &inEdges[0];
float dp_prev;
unsigned outcount = 0;
dp_prev = getclipdist(clipper, vert_prev, plane_idx);
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 = getclipdist(clipper, vert, plane_idx);
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, viewport_index );
/* 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, viewport_index );
/* 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->num_flat_attribs) {
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_flat(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_flat(stage, inlist[0], header->v[2]);
}
}
}
/* Emit the polygon as triangles to the setup stage:
*/
emit_poly( stage, inlist, inEdges, 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 clip_stage *clipper = clip_stage( stage );
struct vertex_header *v0 = header->v[0];
struct vertex_header *v1 = header->v[1];
float t0 = 0.0F;
float t1 = 0.0F;
struct prim_header newprim;
int viewport_index = draw_viewport_index(clipper->stage.draw, v0);
while (clipmask) {
const unsigned plane_idx = ffs(clipmask)-1;
const float dp0 = getclipdist(clipper, v0, plane_idx);
const float dp1 = getclipdist(clipper, v1, plane_idx);
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, viewport_index );
copy_flat(stage, stage->tmp[0], v0);
newprim.v[0] = stage->tmp[0];
}
else {
newprim.v[0] = v0;
}
if (v1->clipmask) {
interp( clipper, stage->tmp[1], t1, v1, v0, viewport_index );
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);
}
}
/* Update state. Could further delay this until we hit the first
* primitive that really requires clipping.
*/
static void
clip_init_state( struct draw_stage *stage )
{
struct clip_stage *clipper = clip_stage( stage );
const struct draw_vertex_shader *vs = stage->draw->vs.vertex_shader;
const struct draw_geometry_shader *gs = stage->draw->gs.geometry_shader;
const struct draw_fragment_shader *fs = stage->draw->fs.fragment_shader;
uint i;
const struct tgsi_shader_info *vs_info = gs ? &gs->info : &vs->info;
/* We need to know for each attribute what kind of interpolation is
* done on it (flat, smooth or noperspective). But the information
* is not directly accessible for outputs, only for inputs. So we
* have to match semantic name and index between the VS (or GS/ES)
* outputs and the FS inputs to get to the interpolation mode.
*
* The only hitch is with gl_FrontColor/gl_BackColor which map to
* gl_Color, and their Secondary versions. First there are (up to)
* two outputs for one input, so we tuck the information in a
* specific array. Second if they don't have qualifiers, the
* default value has to be picked from the global shade mode.
*
* Of course, if we don't have a fragment shader in the first
* place, defaults should be used.
*/
/* First pick up the interpolation mode for
* gl_Color/gl_SecondaryColor, with the correct default.
*/
int indexed_interp[2];
indexed_interp[0] = indexed_interp[1] = stage->draw->rasterizer->flatshade ?
TGSI_INTERPOLATE_CONSTANT : TGSI_INTERPOLATE_PERSPECTIVE;
if (fs) {
for (i = 0; i < fs->info.num_inputs; i++) {
if (fs->info.input_semantic_name[i] == TGSI_SEMANTIC_COLOR) {
if (fs->info.input_interpolate[i] != TGSI_INTERPOLATE_COLOR)
indexed_interp[fs->info.input_semantic_index[i]] = fs->info.input_interpolate[i];
}
}
}
/* Then resolve the interpolation mode for every output attribute.
*
* Given how the rest of the code, the most efficient way is to
* have a vector of flat-mode attributes, and a mask for
* noperspective attributes.
*/
clipper->num_flat_attribs = 0;
memset(clipper
->noperspective_attribs
, 0, sizeof(clipper
->noperspective_attribs
)); for (i = 0; i < vs_info->num_outputs; i++) {
/* Find the interpolation mode for a specific attribute
*/
int interp;
/* If it's gl_{Front,Back}{,Secondary}Color, pick up the mode
* from the array we've filled before. */
if (vs_info->output_semantic_name[i] == TGSI_SEMANTIC_COLOR ||
vs_info->output_semantic_name[i] == TGSI_SEMANTIC_BCOLOR) {
interp = indexed_interp[vs_info->output_semantic_index[i]];
} else {
/* Otherwise, search in the FS inputs, with a decent default
* if we don't find it.
*/
uint j;
interp = TGSI_INTERPOLATE_PERSPECTIVE;
if (fs) {
for (j = 0; j < fs->info.num_inputs; j++) {
if (vs_info->output_semantic_name[i] == fs->info.input_semantic_name[j] &&
vs_info->output_semantic_index[i] == fs->info.input_semantic_index[j]) {
interp = fs->info.input_interpolate[j];
break;
}
}
}
}
/* If it's flat, add it to the flat vector. Otherwise update
* the noperspective mask.
*/
if (interp == TGSI_INTERPOLATE_CONSTANT) {
clipper->flat_attribs[clipper->num_flat_attribs] = i;
clipper->num_flat_attribs++;
} else
clipper->noperspective_attribs[i] = interp == TGSI_INTERPOLATE_LINEAR;
}
stage->tri = clip_tri;
stage->line = clip_line;
}
static void clip_first_tri( struct draw_stage *stage,
struct prim_header *header )
{
clip_init_state( stage );
stage->tri( stage, header );
}
static void clip_first_line( struct draw_stage *stage,
struct prim_header *header )
{
clip_init_state( stage );
stage->line( stage, header );
}
static void clip_flush( struct draw_stage *stage,
unsigned flags )
{
stage->tri = clip_first_tri;
stage->line = clip_first_line;
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_temp_verts( 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 clip_stage *clipper = CALLOC_STRUCT(clip_stage);
if (clipper == NULL)
goto fail;
clipper->stage.draw = draw;
clipper->stage.name = "clipper";
clipper->stage.point = clip_point;
clipper->stage.line = clip_first_line;
clipper->stage.tri = clip_first_tri;
clipper->stage.flush = clip_flush;
clipper->stage.reset_stipple_counter = clip_reset_stipple_counter;
clipper->stage.destroy = clip_destroy;
clipper->plane = draw->plane;
if (!draw_alloc_temp_verts( &clipper->stage, MAX_CLIPPED_VERTICES+1 ))
goto fail;
return &clipper->stage;
fail:
if (clipper)
clipper->stage.destroy( &clipper->stage );
return NULL;
}