Merge pull request #76959 from SurFlurer/fix-light-arc

Fix floating-point precision problem in apply_light_arc

src/lightmap.cpp

@@ -1318,153 +1318,75 @@ void map::apply_light_arc( const tripoint_bub_ms &p, const units::angle &angle,
  cata::mdarray<float, point_bub_ms> &transparency_cache =
  cache.transparency_cache;
 
- // Normalize (should work with negative values too)
- units::angle wangle = wideangle / 2.0;
- units::angle oangle = angle - wangle;
- units::angle cangle = angle + wangle;
-
- //cut pre-subsection
- if( fmod( oangle, 45_degrees ) != 0_degrees ) {
- units::angle preangle = oangle;
- oangle = 45_degrees * std::ceil( to_degrees( oangle ) / 45 );
- switch( static_cast<int>( std::floor( ( preangle + 360_degrees ) / 45_degrees ) ) % 8 ) {
+ const units::angle wangle = wideangle / 2.0;
+ // Normalize so oangle is between 0 and 360 degrees
+ const units::angle oangle = fmod( fmod( angle - wangle, 360_degrees ) + 360_degrees, 360_degrees );
+ const units::angle cangle = oangle + wideangle;
+
+ // Sweep over every octant
+ int i = 0;
+ while( true ) {
+ int start = i;
+ int end = i + 1;
+ units::angle start_angle;
+ units::angle end_angle;
+ // This octant doesn't overlap with illuminated area
+ if( 45_degrees * end < oangle ) {
+ ++i;
+ continue;
+ }
+ // Finish processing
+ if( 45_degrees * start > cangle ) {
+ break;
+ }
+ // Unified way to cast light in one octant
+ start_angle = std::max( 45_degrees * start, oangle );
+ end_angle = std::min( 45_degrees * end, cangle );
+
+ // i is positive
+ switch( i % 8 ) {
  case 0:
  castLight < 0, -1, -1, 0, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, 1.0, tan( preangle ) );
+ lm, transparency_cache, p2, 0, luminance, 1, tan( end_angle ), tan( start_angle ) );
  break;
  case 1:
  castLight < -1, 0, 0, -1, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, cot( preangle ), 0.0 );
+ lm, transparency_cache, p2, 0, luminance, 1, cot( start_angle ), cot( end_angle ) );
  break;
  case 2:
  castLight < 1, 0, 0, -1, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, 1.0, -cot( preangle ) );
+ lm, transparency_cache, p2, 0, luminance, 1, -cot( end_angle ), -cot( start_angle ) );
  break;
  case 3:
  castLight < 0, 1, -1, 0, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, -tan( preangle ), 0.0 );
+ lm, transparency_cache, p2, 0, luminance, 1, -tan( start_angle ), -tan( end_angle ) );
  break;
  case 4:
  castLight < 0, 1, 1, 0, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency >(
- lm, transparency_cache, p2, 0, luminance, 1, 1.0, tan( preangle ) );
+ lm, transparency_cache, p2, 0, luminance, 1, tan( end_angle ), tan( start_angle ) );
  break;
  case 5:
  castLight < 1, 0, 0, 1, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency >(
- lm, transparency_cache, p2, 0, luminance, 1, cot( preangle ), 0.0 );
+ lm, transparency_cache, p2, 0, luminance, 1, cot( start_angle ), cot( end_angle ) );
  break;
  case 6:
  castLight < -1, 0, 0, 1, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, 1.0, -cot( preangle ) );
+ lm, transparency_cache, p2, 0, luminance, 1, -cot( end_angle ), -cot( start_angle ) );
  break;
  case 7:
  castLight < 0, -1, 1, 0, float, four_quadrants, light_calc, light_check,
  update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, -tan( preangle ), 0.0 );
+ lm, transparency_cache, p2, 0, luminance, 1, -tan( start_angle ), -tan( end_angle ) );
  break;
  }
- }
- int numoct = std::floor( to_degrees( cangle - oangle ) / 45 );
- int firstoct = static_cast<int>( std::lround( to_degrees( oangle ) / 45 ) );
- oangle += numoct * 45_degrees;
- wangle = cangle - oangle;
-
- for( int i = firstoct; i < numoct + firstoct; i++ ) {
- //if arc crosses 0 degrees, i.e. sectors 7-0-1, offset back to sector 0 after 7
- switch( ( i + 8 ) % 8 ) {
- case 0:
- castLight < 0, -1, -1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 1:
- castLight < -1, 0, 0, -1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 2:
- castLight < 1, 0, 0, -1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 3:
- castLight < 0, 1, -1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 4:
- castLight < 0, 1, 1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 5:
- castLight < 1, 0, 0, 1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 6:
- castLight < -1, 0, 0, 1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- case 7:
- castLight < 0, -1, 1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance );
- break;
- }
- }
- if( wangle == 0_degrees ) {
- return;
- }
-
- switch( static_cast<int>( std::floor( oangle / 45_degrees ) ) % 8 ) {
- case 0:
- castLight < 0, -1, -1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, tan( cangle ), tan( oangle ) );
- break;
- case 1:
- castLight < -1, 0, 0, -1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, cot( oangle ), cot( cangle ) );
- break;
- case 2:
- castLight < 1, 0, 0, -1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, -cot( cangle ), -cot( oangle ) );
- break;
- case 3:
- castLight < 0, 1, -1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, -tan( oangle ), -tan( cangle ) );
- break;
- case 4:
- castLight < 0, 1, 1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency >(
- lm, transparency_cache, p2, 0, luminance, 1, tan( cangle ), tan( oangle ) );
- break;
- case 5:
- castLight < 1, 0, 0, 1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency >(
- lm, transparency_cache, p2, 0, luminance, 1, cot( oangle ), cot( cangle ) );
- break;
- case 6:
- castLight < -1, 0, 0, 1, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, -cot( cangle ), -cot( oangle ) );
- break;
- case 7:
- castLight < 0, -1, 1, 0, float, four_quadrants, light_calc, light_check,
- update_light_quadrants, accumulate_transparency > (
- lm, transparency_cache, p2, 0, luminance, 1, -tan( oangle ), -tan( cangle ) );
- break;
+ i++;
  }
 }