forked from KolibriOS/kolibrios
227 lines
6.0 KiB
C
227 lines
6.0 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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/**
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* \brief polygon offset state
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*
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* \author Keith Whitwell <keith@tungstengraphics.com>
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* \author Brian Paul
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*/
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#include "util/u_math.h"
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#include "util/u_memory.h"
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#include "draw_pipe.h"
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struct offset_stage {
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struct draw_stage stage;
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float scale;
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float units;
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float clamp;
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};
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static INLINE struct offset_stage *offset_stage( struct draw_stage *stage )
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{
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return (struct offset_stage *) stage;
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}
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/**
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* Offset tri Z. Some hardware can handle this, but not usually when
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* doing unfilled rendering.
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*/
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static void do_offset_tri( struct draw_stage *stage,
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struct prim_header *header )
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{
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const unsigned pos = draw_current_shader_position_output(stage->draw);
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struct offset_stage *offset = offset_stage(stage);
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float inv_det = 1.0f / header->det;
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/* Window coords:
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*/
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float *v0 = header->v[0]->data[pos];
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float *v1 = header->v[1]->data[pos];
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float *v2 = header->v[2]->data[pos];
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/* edge vectors e = v0 - v2, f = v1 - v2 */
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float ex = v0[0] - v2[0];
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float ey = v0[1] - v2[1];
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float ez = v0[2] - v2[2];
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float fx = v1[0] - v2[0];
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float fy = v1[1] - v2[1];
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float fz = v1[2] - v2[2];
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/* (a,b) = cross(e,f).xy */
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float a = ey*fz - ez*fy;
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float b = ez*fx - ex*fz;
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float dzdx = fabsf(a * inv_det);
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float dzdy = fabsf(b * inv_det);
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float zoffset = offset->units + MAX2(dzdx, dzdy) * offset->scale;
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if (offset->clamp)
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zoffset = (offset->clamp < 0.0f) ? MAX2(zoffset, offset->clamp) :
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MIN2(zoffset, offset->clamp);
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/*
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* Note: we're applying the offset and clamping per-vertex.
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* Ideally, the offset is applied per-fragment prior to fragment shading.
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*/
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v0[2] = CLAMP(v0[2] + zoffset, 0.0f, 1.0f);
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v1[2] = CLAMP(v1[2] + zoffset, 0.0f, 1.0f);
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v2[2] = CLAMP(v2[2] + zoffset, 0.0f, 1.0f);
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stage->next->tri( stage->next, header );
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}
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static void offset_tri( struct draw_stage *stage,
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struct prim_header *header )
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{
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struct prim_header tmp;
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tmp.det = header->det;
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tmp.flags = header->flags;
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tmp.pad = header->pad;
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tmp.v[0] = dup_vert(stage, header->v[0], 0);
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tmp.v[1] = dup_vert(stage, header->v[1], 1);
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tmp.v[2] = dup_vert(stage, header->v[2], 2);
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do_offset_tri( stage, &tmp );
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}
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static void offset_first_tri( struct draw_stage *stage,
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struct prim_header *header )
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{
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struct offset_stage *offset = offset_stage(stage);
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const struct pipe_rasterizer_state *rast = stage->draw->rasterizer;
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unsigned fill_mode = rast->fill_front;
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boolean do_offset;
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if (rast->fill_back != rast->fill_front) {
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/* Need to check for back-facing triangle */
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boolean ccw = header->det < 0.0f;
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if (ccw != rast->front_ccw)
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fill_mode = rast->fill_back;
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}
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/* Now determine if we need to do offsetting for the point/line/fill mode */
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switch (fill_mode) {
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case PIPE_POLYGON_MODE_FILL:
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do_offset = rast->offset_tri;
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break;
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case PIPE_POLYGON_MODE_LINE:
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do_offset = rast->offset_line;
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break;
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case PIPE_POLYGON_MODE_POINT:
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do_offset = rast->offset_point;
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break;
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default:
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assert(!"invalid fill_mode in offset_first_tri()");
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do_offset = rast->offset_tri;
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}
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if (do_offset) {
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offset->scale = rast->offset_scale;
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offset->clamp = rast->offset_clamp;
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offset->units = (float) (rast->offset_units * stage->draw->mrd);
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}
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else {
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offset->scale = 0.0f;
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offset->clamp = 0.0f;
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offset->units = 0.0f;
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}
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stage->tri = offset_tri;
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stage->tri( stage, header );
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}
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static void offset_flush( struct draw_stage *stage,
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unsigned flags )
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{
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stage->tri = offset_first_tri;
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stage->next->flush( stage->next, flags );
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}
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static void offset_reset_stipple_counter( struct draw_stage *stage )
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{
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stage->next->reset_stipple_counter( stage->next );
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}
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static void offset_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 polygon offset drawing stage.
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*/
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struct draw_stage *draw_offset_stage( struct draw_context *draw )
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{
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struct offset_stage *offset = CALLOC_STRUCT(offset_stage);
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if (offset == NULL)
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goto fail;
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offset->stage.draw = draw;
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offset->stage.name = "offset";
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offset->stage.next = NULL;
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offset->stage.point = draw_pipe_passthrough_point;
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offset->stage.line = draw_pipe_passthrough_line;
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offset->stage.tri = offset_first_tri;
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offset->stage.flush = offset_flush;
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offset->stage.reset_stipple_counter = offset_reset_stipple_counter;
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offset->stage.destroy = offset_destroy;
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if (!draw_alloc_temp_verts( &offset->stage, 3 ))
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goto fail;
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return &offset->stage;
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fail:
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if (offset)
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offset->stage.destroy( &offset->stage );
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return NULL;
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}
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