1 /************************************************************************** 2 * 3 * Copyright 2007 Tungsten Graphics, Inc., Cedar Park, Texas. 4 * All Rights Reserved. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a 7 * copy of this software and associated documentation files (the 8 * "Software"), to deal in the Software without restriction, including 9 * without limitation the rights to use, copy, modify, merge, publish, 10 * distribute, sub license, and/or sell copies of the Software, and to 11 * permit persons to whom the Software is furnished to do so, subject to 12 * the following conditions: 13 * 14 * The above copyright notice and this permission notice (including the 15 * next paragraph) shall be included in all copies or substantial portions 16 * of the Software. 17 * 18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. 21 * IN NO EVENT SHALL TUNGSTEN GRAPHICS AND/OR ITS SUPPLIERS BE LIABLE FOR 22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 25 * 26 **************************************************************************/ 27 28 /** 29 * \brief polygon offset state 30 * 31 * \author Keith Whitwell <keith (at) tungstengraphics.com> 32 * \author Brian Paul 33 */ 34 35 #include "util/u_math.h" 36 #include "util/u_memory.h" 37 #include "draw_pipe.h" 38 39 40 41 struct offset_stage { 42 struct draw_stage stage; 43 44 float scale; 45 float units; 46 float clamp; 47 }; 48 49 50 51 static INLINE struct offset_stage *offset_stage( struct draw_stage *stage ) 52 { 53 return (struct offset_stage *) stage; 54 } 55 56 57 58 59 60 /** 61 * Offset tri Z. Some hardware can handle this, but not usually when 62 * doing unfilled rendering. 63 */ 64 static void do_offset_tri( struct draw_stage *stage, 65 struct prim_header *header ) 66 { 67 const unsigned pos = draw_current_shader_position_output(stage->draw); 68 struct offset_stage *offset = offset_stage(stage); 69 float inv_det = 1.0f / header->det; 70 71 /* Window coords: 72 */ 73 float *v0 = header->v[0]->data[pos]; 74 float *v1 = header->v[1]->data[pos]; 75 float *v2 = header->v[2]->data[pos]; 76 77 /* edge vectors e = v0 - v2, f = v1 - v2 */ 78 float ex = v0[0] - v2[0]; 79 float ey = v0[1] - v2[1]; 80 float ez = v0[2] - v2[2]; 81 float fx = v1[0] - v2[0]; 82 float fy = v1[1] - v2[1]; 83 float fz = v1[2] - v2[2]; 84 85 /* (a,b) = cross(e,f).xy */ 86 float a = ey*fz - ez*fy; 87 float b = ez*fx - ex*fz; 88 89 float dzdx = fabsf(a * inv_det); 90 float dzdy = fabsf(b * inv_det); 91 92 float zoffset = offset->units + MAX2(dzdx, dzdy) * offset->scale; 93 94 if (offset->clamp) 95 zoffset = (offset->clamp < 0.0f) ? MAX2(zoffset, offset->clamp) : 96 MIN2(zoffset, offset->clamp); 97 98 /* 99 * Note: we're applying the offset and clamping per-vertex. 100 * Ideally, the offset is applied per-fragment prior to fragment shading. 101 */ 102 v0[2] = CLAMP(v0[2] + zoffset, 0.0f, 1.0f); 103 v1[2] = CLAMP(v1[2] + zoffset, 0.0f, 1.0f); 104 v2[2] = CLAMP(v2[2] + zoffset, 0.0f, 1.0f); 105 106 stage->next->tri( stage->next, header ); 107 } 108 109 110 static void offset_tri( struct draw_stage *stage, 111 struct prim_header *header ) 112 { 113 struct prim_header tmp; 114 115 tmp.det = header->det; 116 tmp.flags = header->flags; 117 tmp.pad = header->pad; 118 tmp.v[0] = dup_vert(stage, header->v[0], 0); 119 tmp.v[1] = dup_vert(stage, header->v[1], 1); 120 tmp.v[2] = dup_vert(stage, header->v[2], 2); 121 122 do_offset_tri( stage, &tmp ); 123 } 124 125 126 static void offset_first_tri( struct draw_stage *stage, 127 struct prim_header *header ) 128 { 129 struct offset_stage *offset = offset_stage(stage); 130 131 offset->units = (float) (stage->draw->rasterizer->offset_units * stage->draw->mrd); 132 offset->scale = stage->draw->rasterizer->offset_scale; 133 offset->clamp = stage->draw->rasterizer->offset_clamp; 134 135 stage->tri = offset_tri; 136 stage->tri( stage, header ); 137 } 138 139 140 141 142 static void offset_flush( struct draw_stage *stage, 143 unsigned flags ) 144 { 145 stage->tri = offset_first_tri; 146 stage->next->flush( stage->next, flags ); 147 } 148 149 150 static void offset_reset_stipple_counter( struct draw_stage *stage ) 151 { 152 stage->next->reset_stipple_counter( stage->next ); 153 } 154 155 156 static void offset_destroy( struct draw_stage *stage ) 157 { 158 draw_free_temp_verts( stage ); 159 FREE( stage ); 160 } 161 162 163 /** 164 * Create polygon offset drawing stage. 165 */ 166 struct draw_stage *draw_offset_stage( struct draw_context *draw ) 167 { 168 struct offset_stage *offset = CALLOC_STRUCT(offset_stage); 169 if (offset == NULL) 170 goto fail; 171 172 offset->stage.draw = draw; 173 offset->stage.name = "offset"; 174 offset->stage.next = NULL; 175 offset->stage.point = draw_pipe_passthrough_point; 176 offset->stage.line = draw_pipe_passthrough_line; 177 offset->stage.tri = offset_first_tri; 178 offset->stage.flush = offset_flush; 179 offset->stage.reset_stipple_counter = offset_reset_stipple_counter; 180 offset->stage.destroy = offset_destroy; 181 182 if (!draw_alloc_temp_verts( &offset->stage, 3 )) 183 goto fail; 184 185 return &offset->stage; 186 187 fail: 188 if (offset) 189 offset->stage.destroy( &offset->stage ); 190 191 return NULL; 192 } 193
