262 lines
7.0 KiB
C
262 lines
7.0 KiB
C
/**************************************************************************
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*
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* Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas.
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* All Rights Reserved.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sub license, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice (including the
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* next paragraph) shall be included in all copies or substantial portions
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* of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
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* IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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**************************************************************************/
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/* Authors: Keith Whitwell <keith@tungstengraphics.com>
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*/
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/* Implement line stipple by cutting lines up into smaller lines.
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* There are hundreds of ways to implement line stipple, this is one
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* choice that should work in all situations, requires no state
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* manipulations, but with a penalty in terms of large amounts of
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* generated geometry.
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*/
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#include "pipe/p_defines.h"
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#include "pipe/p_shader_tokens.h"
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#include "util/u_math.h"
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#include "util/u_memory.h"
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#include "draw/draw_pipe.h"
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/** Subclass of draw_stage */
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struct stipple_stage {
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struct draw_stage stage;
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float counter;
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uint pattern;
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uint factor;
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};
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static INLINE struct stipple_stage *
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stipple_stage(struct draw_stage *stage)
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{
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return (struct stipple_stage *) stage;
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}
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/**
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* Compute interpolated vertex attributes for 'dst' at position 't'
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* between 'v0' and 'v1'.
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* XXX using linear interpolation for all attribs at this time.
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*/
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static void
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screen_interp( struct draw_context *draw,
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struct vertex_header *dst,
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float t,
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const struct vertex_header *v0,
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const struct vertex_header *v1 )
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{
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uint attr;
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uint num_outputs = draw_current_shader_outputs(draw);
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for (attr = 0; attr < num_outputs; attr++) {
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const float *val0 = v0->data[attr];
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const float *val1 = v1->data[attr];
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float *newv = dst->data[attr];
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uint i;
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for (i = 0; i < 4; i++) {
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newv[i] = val0[i] + t * (val1[i] - val0[i]);
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}
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}
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}
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static void
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emit_segment(struct draw_stage *stage, struct prim_header *header,
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float t0, float t1)
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{
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struct vertex_header *v0new = dup_vert(stage, header->v[0], 0);
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struct vertex_header *v1new = dup_vert(stage, header->v[1], 1);
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struct prim_header newprim = *header;
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if (t0 > 0.0) {
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screen_interp( stage->draw, v0new, t0, header->v[0], header->v[1] );
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newprim.v[0] = v0new;
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}
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if (t1 < 1.0) {
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screen_interp( stage->draw, v1new, t1, header->v[0], header->v[1] );
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newprim.v[1] = v1new;
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}
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stage->next->line( stage->next, &newprim );
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}
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static INLINE unsigned
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stipple_test(int counter, ushort pattern, int factor)
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{
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int b = (counter / factor) & 0xf;
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return (1 << b) & pattern;
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}
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static void
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stipple_line(struct draw_stage *stage, struct prim_header *header)
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{
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struct stipple_stage *stipple = stipple_stage(stage);
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struct vertex_header *v0 = header->v[0];
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struct vertex_header *v1 = header->v[1];
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const unsigned pos = draw_current_shader_position_output(stage->draw);
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const float *pos0 = v0->data[pos];
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const float *pos1 = v1->data[pos];
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float start = 0;
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int state = 0;
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float x0 = pos0[0];
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float x1 = pos1[0];
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float y0 = pos0[1];
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float y1 = pos1[1];
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float dx = x0 > x1 ? x0 - x1 : x1 - x0;
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float dy = y0 > y1 ? y0 - y1 : y1 - y0;
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float length = MAX2(dx, dy);
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int i;
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if (header->flags & DRAW_PIPE_RESET_STIPPLE)
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stipple->counter = 0;
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/* XXX ToDo: intead of iterating pixel-by-pixel, use a look-up table.
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*/
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for (i = 0; i < length; i++) {
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int result = stipple_test( (int) stipple->counter+i,
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(ushort) stipple->pattern, stipple->factor );
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if (result != state) {
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/* changing from "off" to "on" or vice versa */
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if (state) {
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if (start != i) {
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/* finishing an "on" segment */
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emit_segment( stage, header, start / length, i / length );
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}
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}
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else {
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/* starting an "on" segment */
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start = (float) i;
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}
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state = result;
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}
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}
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if (state && start < length)
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emit_segment( stage, header, start / length, 1.0 );
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stipple->counter += length;
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}
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static void
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reset_stipple_counter(struct draw_stage *stage)
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{
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struct stipple_stage *stipple = stipple_stage(stage);
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stipple->counter = 0;
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stage->next->reset_stipple_counter( stage->next );
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}
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static void
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stipple_reset_point(struct draw_stage *stage, struct prim_header *header)
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{
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struct stipple_stage *stipple = stipple_stage(stage);
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stipple->counter = 0;
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stage->next->point(stage->next, header);
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}
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static void
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stipple_reset_tri(struct draw_stage *stage, struct prim_header *header)
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{
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struct stipple_stage *stipple = stipple_stage(stage);
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stipple->counter = 0;
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stage->next->tri(stage->next, header);
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}
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static void
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stipple_first_line(struct draw_stage *stage,
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struct prim_header *header)
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{
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struct stipple_stage *stipple = stipple_stage(stage);
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struct draw_context *draw = stage->draw;
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stipple->pattern = draw->rasterizer->line_stipple_pattern;
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stipple->factor = draw->rasterizer->line_stipple_factor + 1;
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stage->line = stipple_line;
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stage->line( stage, header );
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}
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static void
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stipple_flush(struct draw_stage *stage, unsigned flags)
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{
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stage->line = stipple_first_line;
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stage->next->flush( stage->next, flags );
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}
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static void
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stipple_destroy( struct draw_stage *stage )
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{
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draw_free_temp_verts( stage );
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FREE( stage );
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}
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/**
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* Create line stippler stage
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*/
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struct draw_stage *draw_stipple_stage( struct draw_context *draw )
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{
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struct stipple_stage *stipple = CALLOC_STRUCT(stipple_stage);
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if (stipple == NULL)
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goto fail;
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stipple->stage.draw = draw;
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stipple->stage.name = "stipple";
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stipple->stage.next = NULL;
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stipple->stage.point = stipple_reset_point;
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stipple->stage.line = stipple_first_line;
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stipple->stage.tri = stipple_reset_tri;
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stipple->stage.reset_stipple_counter = reset_stipple_counter;
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stipple->stage.flush = stipple_flush;
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stipple->stage.destroy = stipple_destroy;
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if (!draw_alloc_temp_verts( &stipple->stage, 2 ))
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goto fail;
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return &stipple->stage;
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fail:
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if (stipple)
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stipple->stage.destroy( &stipple->stage );
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return NULL;
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}
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