/**************************************************************************
*
* 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.
*
**************************************************************************/
/* Authors: Keith Whitwell <keith@tungstengraphics.com>
*/
/* Implement line stipple by cutting lines up into smaller lines.
* There are hundreds of ways to implement line stipple, this is one
* choice that should work in all situations, requires no state
* manipulations, but with a penalty in terms of large amounts of
* generated geometry.
*/
#include "pipe/p_defines.h"
#include "pipe/p_shader_tokens.h"
#include "util/u_math.h"
#include "util/u_memory.h"
#include "draw/draw_pipe.h"
/** Subclass of draw_stage */
struct stipple_stage {
struct draw_stage stage;
float counter;
uint pattern;
uint factor;
};
static INLINE struct stipple_stage *
stipple_stage(struct draw_stage *stage)
{
return (struct stipple_stage *) stage;
}
/**
* Compute interpolated vertex attributes for 'dst' at position 't'
* between 'v0' and 'v1'.
* XXX using linear interpolation for all attribs at this time.
*/
static void
screen_interp( struct draw_context *draw,
struct vertex_header *dst,
float t,
const struct vertex_header *v0,
const struct vertex_header *v1 )
{
uint attr;
uint num_outputs = draw_current_shader_outputs(draw);
for (attr = 0; attr < num_outputs; attr++) {
const float *val0 = v0->data[attr];
const float *val1 = v1->data[attr];
float *newv = dst->data[attr];
uint i;
for (i = 0; i < 4; i++) {
newv[i] = val0[i] + t * (val1[i] - val0[i]);
}
}
}
static void
emit_segment(struct draw_stage *stage, struct prim_header *header,
float t0, float t1)
{
struct vertex_header *v0new = dup_vert(stage, header->v[0], 0);
struct vertex_header *v1new = dup_vert(stage, header->v[1], 1);
struct prim_header newprim = *header;
if (t0 > 0.0) {
screen_interp( stage->draw, v0new, t0, header->v[0], header->v[1] );
newprim.v[0] = v0new;
}
if (t1 < 1.0) {
screen_interp( stage->draw, v1new, t1, header->v[0], header->v[1] );
newprim.v[1] = v1new;
}
stage->next->line( stage->next, &newprim );
}
static INLINE unsigned
stipple_test(int counter, ushort pattern, int factor)
{
int b = (counter / factor) & 0xf;
return (1 << b) & pattern;
}
static void
stipple_line(struct draw_stage *stage, struct prim_header *header)
{
struct stipple_stage *stipple = stipple_stage(stage);
struct vertex_header *v0 = header->v[0];
struct vertex_header *v1 = header->v[1];
const unsigned pos = draw_current_shader_position_output(stage->draw);
const float *pos0 = v0->data[pos];
const float *pos1 = v1->data[pos];
float start = 0;
int state = 0;
float x0 = pos0[0];
float x1 = pos1[0];
float y0 = pos0[1];
float y1 = pos1[1];
float dx = x0 > x1 ? x0 - x1 : x1 - x0;
float dy = y0 > y1 ? y0 - y1 : y1 - y0;
float length = MAX2(dx, dy);
int i;
if (header->flags & DRAW_PIPE_RESET_STIPPLE)
stipple->counter = 0;
/* XXX ToDo: intead of iterating pixel-by-pixel, use a look-up table.
*/
for (i = 0; i < length; i++) {
int result = stipple_test( (int) stipple->counter+i,
(ushort) stipple->pattern, stipple->factor );
if (result != state) {
/* changing from "off" to "on" or vice versa */
if (state) {
if (start != i) {
/* finishing an "on" segment */
emit_segment( stage, header, start / length, i / length );
}
}
else {
/* starting an "on" segment */
start = (float) i;
}
state = result;
}
}
if (state && start < length)
emit_segment( stage, header, start / length, 1.0 );
stipple->counter += length;
}
static void
reset_stipple_counter(struct draw_stage *stage)
{
struct stipple_stage *stipple = stipple_stage(stage);
stipple->counter = 0;
stage->next->reset_stipple_counter( stage->next );
}
static void
stipple_reset_point(struct draw_stage *stage, struct prim_header *header)
{
struct stipple_stage *stipple = stipple_stage(stage);
stipple->counter = 0;
stage->next->point(stage->next, header);
}
static void
stipple_reset_tri(struct draw_stage *stage, struct prim_header *header)
{
struct stipple_stage *stipple = stipple_stage(stage);
stipple->counter = 0;
stage->next->tri(stage->next, header);
}
static void
stipple_first_line(struct draw_stage *stage,
struct prim_header *header)
{
struct stipple_stage *stipple = stipple_stage(stage);
struct draw_context *draw = stage->draw;
stipple->pattern = draw->rasterizer->line_stipple_pattern;
stipple->factor = draw->rasterizer->line_stipple_factor + 1;
stage->line = stipple_line;
stage->line( stage, header );
}
static void
stipple_flush(struct draw_stage *stage, unsigned flags)
{
stage->line = stipple_first_line;
stage->next->flush( stage->next, flags );
}
static void
stipple_destroy( struct draw_stage *stage )
{
draw_free_temp_verts( stage );
FREE( stage );
}
/**
* Create line stippler stage
*/
struct draw_stage *draw_stipple_stage( struct draw_context *draw )
{
struct stipple_stage *stipple = CALLOC_STRUCT(stipple_stage);
if (stipple == NULL)
goto fail;
stipple->stage.draw = draw;
stipple->stage.name = "stipple";
stipple->stage.next = NULL;
stipple->stage.point = stipple_reset_point;
stipple->stage.line = stipple_first_line;
stipple->stage.tri = stipple_reset_tri;
stipple->stage.reset_stipple_counter = reset_stipple_counter;
stipple->stage.flush = stipple_flush;
stipple->stage.destroy = stipple_destroy;
if (!draw_alloc_temp_verts( &stipple->stage, 2 ))
goto fail;
return &stipple->stage;
fail:
if (stipple)
stipple->stage.destroy( &stipple->stage );
return NULL;
}