/************************************************************************** * * 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 polygon offset state * * \author Keith Whitwell * \author Brian Paul */ #include "util/u_format.h" #include "util/u_math.h" #include "util/u_memory.h" #include "draw_pipe.h" struct offset_stage { struct draw_stage stage; float scale; float units; float clamp; }; static INLINE struct offset_stage *offset_stage( struct draw_stage *stage ) { return (struct offset_stage *) stage; } /** * Offset tri Z. Some hardware can handle this, but not usually when * doing unfilled rendering. */ static void do_offset_tri( struct draw_stage *stage, struct prim_header *header ) { const unsigned pos = draw_current_shader_position_output(stage->draw); struct offset_stage *offset = offset_stage(stage); float inv_det = 1.0f / header->det; /* Window coords: */ float *v0 = header->v[0]->data[pos]; float *v1 = header->v[1]->data[pos]; float *v2 = header->v[2]->data[pos]; /* edge vectors e = v0 - v2, f = v1 - v2 */ float ex = v0[0] - v2[0]; float ey = v0[1] - v2[1]; float ez = v0[2] - v2[2]; float fx = v1[0] - v2[0]; float fy = v1[1] - v2[1]; float fz = v1[2] - v2[2]; /* (a,b) = cross(e,f).xy */ float a = ey*fz - ez*fy; float b = ez*fx - ex*fz; float dzdx = fabsf(a * inv_det); float dzdy = fabsf(b * inv_det); float zoffset, maxz, bias, mult; mult = MAX2(dzdx, dzdy) * offset->scale; if (stage->draw->floating_point_depth) { maxz = MAX3(v0[2], v1[2], v2[2]); /** * XXX: TODO optimize this to quickly resolve a pow2 number through * an exponent only operation. */ bias = offset->units * util_fast_exp2(util_get_float32_exponent(maxz) - 23); zoffset = bias + mult; } else { zoffset = offset->units + mult; } if (offset->clamp) zoffset = (offset->clamp < 0.0f) ? MAX2(zoffset, offset->clamp) : MIN2(zoffset, offset->clamp); /* * Note: we're applying the offset and clamping per-vertex. * Ideally, the offset is applied per-fragment prior to fragment shading. */ v0[2] = CLAMP(v0[2] + zoffset, 0.0f, 1.0f); v1[2] = CLAMP(v1[2] + zoffset, 0.0f, 1.0f); v2[2] = CLAMP(v2[2] + zoffset, 0.0f, 1.0f); stage->next->tri( stage->next, header ); } static void offset_tri( struct draw_stage *stage, struct prim_header *header ) { struct prim_header tmp; tmp.det = header->det; tmp.flags = header->flags; tmp.pad = header->pad; tmp.v[0] = dup_vert(stage, header->v[0], 0); tmp.v[1] = dup_vert(stage, header->v[1], 1); tmp.v[2] = dup_vert(stage, header->v[2], 2); do_offset_tri( stage, &tmp ); } static void offset_first_tri( struct draw_stage *stage, struct prim_header *header ) { struct offset_stage *offset = offset_stage(stage); const struct pipe_rasterizer_state *rast = stage->draw->rasterizer; unsigned fill_mode = rast->fill_front; boolean do_offset; if (rast->fill_back != rast->fill_front) { /* Need to check for back-facing triangle */ boolean ccw = header->det < 0.0f; if (ccw != rast->front_ccw) fill_mode = rast->fill_back; } /* Now determine if we need to do offsetting for the point/line/fill mode */ switch (fill_mode) { case PIPE_POLYGON_MODE_FILL: do_offset = rast->offset_tri; break; case PIPE_POLYGON_MODE_LINE: do_offset = rast->offset_line; break; case PIPE_POLYGON_MODE_POINT: do_offset = rast->offset_point; break; default: assert(!"invalid fill_mode in offset_first_tri()"); do_offset = rast->offset_tri; } if (do_offset) { offset->scale = rast->offset_scale; offset->clamp = rast->offset_clamp; /* * If depth is floating point, depth bias is calculated with respect * to the primitive's maximum Z value. Retain the original depth bias * value until that stage. */ if (stage->draw->floating_point_depth) { offset->units = (float) rast->offset_units; } else { offset->units = (float) (rast->offset_units * stage->draw->mrd); } } else { offset->scale = 0.0f; offset->clamp = 0.0f; offset->units = 0.0f; } stage->tri = offset_tri; stage->tri( stage, header ); } static void offset_flush( struct draw_stage *stage, unsigned flags ) { stage->tri = offset_first_tri; stage->next->flush( stage->next, flags ); } static void offset_reset_stipple_counter( struct draw_stage *stage ) { stage->next->reset_stipple_counter( stage->next ); } static void offset_destroy( struct draw_stage *stage ) { draw_free_temp_verts( stage ); FREE( stage ); } /** * Create polygon offset drawing stage. */ struct draw_stage *draw_offset_stage( struct draw_context *draw ) { struct offset_stage *offset = CALLOC_STRUCT(offset_stage); if (offset == NULL) goto fail; offset->stage.draw = draw; offset->stage.name = "offset"; offset->stage.next = NULL; offset->stage.point = draw_pipe_passthrough_point; offset->stage.line = draw_pipe_passthrough_line; offset->stage.tri = offset_first_tri; offset->stage.flush = offset_flush; offset->stage.reset_stipple_counter = offset_reset_stipple_counter; offset->stage.destroy = offset_destroy; if (!draw_alloc_temp_verts( &offset->stage, 3 )) goto fail; return &offset->stage; fail: if (offset) offset->stage.destroy( &offset->stage ); return NULL; }