/************************************************************************** * * 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 Drawing stage for polygon culling */ /* Authors: Keith Whitwell <keith@tungstengraphics.com> */ #include "util/u_math.h" #include "util/u_memory.h" #include "pipe/p_defines.h" #include "draw_pipe.h" struct cull_stage { struct draw_stage stage; unsigned cull_face; /**< which face(s) to cull (one of PIPE_FACE_x) */ unsigned front_ccw; }; static INLINE struct cull_stage *cull_stage( struct draw_stage *stage ) { return (struct cull_stage *)stage; } static INLINE boolean cull_distance_is_out(float dist) { return (dist < 0.0f) || util_is_inf_or_nan(dist); } /* * If the shader writes the culldistance then we can * perform distance based culling. Distance based * culling doesn't require a face and can be performed * on primitives without faces (e.g. points and lines) */ static void cull_point( struct draw_stage *stage, struct prim_header *header ) { const unsigned num_written_culldistances = draw_current_shader_num_written_culldistances(stage->draw); unsigned i; debug_assert(num_written_culldistances); for (i = 0; i < num_written_culldistances; ++i) { unsigned cull_idx = i / 4; unsigned out_idx = draw_current_shader_culldistance_output(stage->draw, cull_idx); unsigned idx = i % 4; float cull1 = header->v[0]->data[out_idx][idx]; boolean vert1_out = cull_distance_is_out(cull1); if (vert1_out) return; } stage->next->point( stage->next, header ); } /* * If the shader writes the culldistance then we can * perform distance based culling. Distance based * culling doesn't require a face and can be performed * on primitives without faces (e.g. points and lines) */ static void cull_line( struct draw_stage *stage, struct prim_header *header ) { const unsigned num_written_culldistances = draw_current_shader_num_written_culldistances(stage->draw); unsigned i; debug_assert(num_written_culldistances); for (i = 0; i < num_written_culldistances; ++i) { unsigned cull_idx = i / 4; unsigned out_idx = draw_current_shader_culldistance_output(stage->draw, cull_idx); unsigned idx = i % 4; float cull1 = header->v[0]->data[out_idx][idx]; float cull2 = header->v[1]->data[out_idx][idx]; boolean vert1_out = cull_distance_is_out(cull1); boolean vert2_out = cull_distance_is_out(cull2); if (vert1_out && vert2_out) return; } stage->next->line( stage->next, header ); } /* * Triangles can be culled either using the cull distance * shader outputs or the regular face culling. If required * this function performs both, starting with distance culling. */ static void cull_tri( struct draw_stage *stage, struct prim_header *header ) { const unsigned num_written_culldistances = draw_current_shader_num_written_culldistances(stage->draw); /* Do the distance culling */ if (num_written_culldistances) { unsigned i; for (i = 0; i < num_written_culldistances; ++i) { unsigned cull_idx = i / 4; unsigned out_idx = draw_current_shader_culldistance_output(stage->draw, cull_idx); unsigned idx = i % 4; float cull1 = header->v[0]->data[out_idx][idx]; float cull2 = header->v[1]->data[out_idx][idx]; float cull3 = header->v[2]->data[out_idx][idx]; boolean vert1_out = cull_distance_is_out(cull1); boolean vert2_out = cull_distance_is_out(cull2); boolean vert3_out = cull_distance_is_out(cull3); if (vert1_out && vert2_out && vert3_out) return; } } /* Do the regular face culling */ { const unsigned pos = draw_current_shader_position_output(stage->draw); /* Window coords: */ const float *v0 = header->v[0]->data[pos]; const float *v1 = header->v[1]->data[pos]; const float *v2 = header->v[2]->data[pos]; /* edge vectors: e = v0 - v2, f = v1 - v2 */ const float ex = v0[0] - v2[0]; const float ey = v0[1] - v2[1]; const float fx = v1[0] - v2[0]; const float fy = v1[1] - v2[1]; /* det = cross(e,f).z */ header->det = ex * fy - ey * fx; if (header->det != 0) { /* if det < 0 then Z points toward the camera and the triangle is * counter-clockwise winding. */ unsigned ccw = (header->det < 0); unsigned face = ((ccw == cull_stage(stage)->front_ccw) ? PIPE_FACE_FRONT : PIPE_FACE_BACK); if ((face & cull_stage(stage)->cull_face) == 0) { /* triangle is not culled, pass to next stage */ stage->next->tri( stage->next, header ); } } } } static void cull_first_point( struct draw_stage *stage, struct prim_header *header ) { const unsigned num_written_culldistances = draw_current_shader_num_written_culldistances(stage->draw); if (num_written_culldistances) { stage->point = cull_point; stage->point( stage, header ); } else { stage->point = draw_pipe_passthrough_point; stage->point( stage, header ); } } static void cull_first_line( struct draw_stage *stage, struct prim_header *header ) { const unsigned num_written_culldistances = draw_current_shader_num_written_culldistances(stage->draw); if (num_written_culldistances) { stage->line = cull_line; stage->line( stage, header ); } else { stage->line = draw_pipe_passthrough_line; stage->line( stage, header ); } } static void cull_first_tri( struct draw_stage *stage, struct prim_header *header ) { struct cull_stage *cull = cull_stage(stage); cull->cull_face = stage->draw->rasterizer->cull_face; cull->front_ccw = stage->draw->rasterizer->front_ccw; stage->tri = cull_tri; stage->tri( stage, header ); } static void cull_flush( struct draw_stage *stage, unsigned flags ) { stage->point = cull_first_point; stage->line = cull_first_line; stage->tri = cull_first_tri; stage->next->flush( stage->next, flags ); } static void cull_reset_stipple_counter( struct draw_stage *stage ) { stage->next->reset_stipple_counter( stage->next ); } static void cull_destroy( struct draw_stage *stage ) { draw_free_temp_verts( stage ); FREE( stage ); } /** * Create a new polygon culling stage. */ struct draw_stage *draw_cull_stage( struct draw_context *draw ) { struct cull_stage *cull = CALLOC_STRUCT(cull_stage); if (cull == NULL) goto fail; cull->stage.draw = draw; cull->stage.name = "cull"; cull->stage.next = NULL; cull->stage.point = cull_first_point; cull->stage.line = cull_first_line; cull->stage.tri = cull_first_tri; cull->stage.flush = cull_flush; cull->stage.reset_stipple_counter = cull_reset_stipple_counter; cull->stage.destroy = cull_destroy; if (!draw_alloc_temp_verts( &cull->stage, 0 )) goto fail; return &cull->stage; fail: if (cull) cull->stage.destroy( &cull->stage ); return NULL; }