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Merge pull request CleverRaven#76959 from SurFlurer/fix-light-arc
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Fix floating-point precision problem in apply_light_arc
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@Maleclypse
Maleclypse authored Oct 14, 2024
2 parents 1380795 + 34c2d96 commit 2e5b3cf
Showing 1 changed file with 36 additions and 114 deletions.
150 changes: 36 additions & 114 deletions src/lightmap.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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++;
}
}

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