From 8feec5ee3ba551859d787f077d797bc1b19d4dc2 Mon Sep 17 00:00:00 2001 From: Vito Caputo Date: Mon, 10 Oct 2022 19:16:21 -0700 Subject: sars: add ndc->bpc conversion helpers bpc = boxed projection coordinates, this basically comes from eon just like the pillar/letter boxing code for fullscreen stuff did. Previously I didn't need this part of that code, but the touch coordinates are in ndc and those need to get transformed by the projection transform's inverse. --- src/sars.c | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) (limited to 'src/sars.c') diff --git a/src/sars.c b/src/sars.c index 488d459..dc35383 100644 --- a/src/sars.c +++ b/src/sars.c @@ -110,6 +110,44 @@ void sars_viewport_from_ndc(sars_t *sars, float x, float y, int *res_x, int *res } +void sars_ndc_to_bpc(sars_t *sars, float x, float y, float *res_x, float *res_y) +{ + v3f_t coord = { .x = x, .y = y}, res; + + res = m4f_mult_v3f(&sars->projection_x_inv, &coord); + + /* it's not particularly useful to return coordinates outside the projection, + * rather than having everything using this function have to clamp or otherwise + * handle the result within these bounds, just do it here. Callers wanting to + * work with coordinates outside the projection arguably shouldn't be going through + * this transformation in the first place; they're clearly interested + * in viewport/screen-space or canvas-space coordinates, not projection coordinates. + */ + + if (res.x > 1.f) + res.x = 1.f; + else if (res.x < -1.f) + res.x = -1.f; + + if (res.y > 1.f) + res.y = 1.f; + else if (res.y < -1.f) + res.y = -1.f; + + *res_x = res.x; + *res_y = res.y; +} + + +void sars_viewport_to_bpc(sars_t *sars, int x, int y, float *res_x, float *res_y) +{ + v3f_t coord = {}; + + sars_viewport_to_ndc(sars, x, y, &coord.x, &coord.y); + sars_ndc_to_bpc(sars, coord.x, coord.y, res_x, res_y); +} + + uint32_t sars_viewport_id(sars_t *sars) { return SDL_GetWindowID(sars->window); @@ -149,6 +187,8 @@ static void sars_update_projection_x(sars_t *sars) sars->projection_x = m4f_identity(); else sars->projection_x = sars_boxed_projection_x(sars); + + sars->projection_x_inv = m4f_invert(&sars->projection_x); } -- cgit v1.2.3