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| /************************************************************************** |
| * |
| * 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; |
| } |