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More accurate lightgun x-scaling

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David Walters 2017-11-20 09:30:55 +00:00
parent 92ba9ef75d
commit ebcfa83284
1 changed files with 3 additions and 18 deletions
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21
input.cpp
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@ -504,25 +504,10 @@ void input_update( retro_input_state_t input_state_cb )
{
shot_type = ( 1 << 0 ); // On-screen shot!
//
// .. scale into screen space:
// NOTE: this is complete hacky guesswork for this first pass, need to re-write.
//
// Compute a scale for assumed 320 x 240 pixel resolution.
//
// See in [guncon.cpp]GPULineHook:
// gx = (nom_x * 2 + pix_clock_divider) / (pix_clock_divider * 2)
// ### Measured pix_clock_divider as 10 in "Time Crisis"[U] (seems to be consistently 10?)
// gx = (nom_x * 2 + 10) / 20;
// gx * 20 = nom_x * 2 + 10;
// gx * 20 - 10 = nom_x * 2
// nom_x = ( gx * 20 - 10 ) / 2;
// nom_x[@319px] = ( 319 * 20 - 10 ) / 2;
// nom_x[@319px] = 3195;
//
const int scale_x = 3185;
const int scale_y = 239;
// NOTE: these are based on empirical evidence only.
const int scale_x = 2800;
const int scale_y = 240;
gun_x = ( ( gun_x_raw + 0x7fff ) * scale_x ) / (0x7fff << 1);
gun_y = ( ( gun_y_raw + 0x7fff ) * scale_y ) / (0x7fff << 1);