archeus/src/math/rectangle.c

#include "arc/math/rectangle.h"
#include "arc/std/bool.h"

//VERY TEMP
// #include <SDL.h>

void ARC_Rect_CenterOn(ARC_Rect *rect, ARC_Rect bounds){
    rect->x = (bounds.x + (bounds.w / 2)) - (rect->w / 2);
    rect->y = (bounds.y + (bounds.h / 2)) - (rect->h / 2);
}

void ARC_FRect_CenterOn(ARC_FRect *rect, ARC_FRect bounds){
    rect->x = (bounds.x + (bounds.w / 2.0f)) - (rect->w / 2.0f);
    rect->y = (bounds.y + (bounds.h / 2.0f)) - (rect->h / 2.0f);
}

ARC_FRect ARC_Rect_CastToFRect(ARC_Rect rect){
    return (ARC_FRect){
        .x = (float)rect.x,
        .y = (float)rect.y,
        .w = (float)rect.w,
        .h = (float)rect.h,
    };
}

ARC_Rect ARC_FRect_CastToRect(ARC_FRect rect){
    return (ARC_Rect){
        .x = (int32_t)rect.x,
        .y = (int32_t)rect.y,
        .w = (int32_t)rect.w,
        .h = (int32_t)rect.h,
    };
}

ARC_Bool ARC_Rect_Intersects(ARC_Rect rect1, ARC_Rect rect2){
    if(rect1.x <= rect2.x + rect2.w && rect1.x + rect1.w >= rect2.x &&
       rect1.y <= rect2.y + rect2.h && rect1.y + rect1.h >= rect2.y){
        return ARC_True;
    }
    return ARC_False;
}

ARC_Bool ARC_FRect_Intersects(ARC_FRect rect1, ARC_FRect rect2){
    if(rect1.x <= rect2.x + rect2.w && rect1.x + rect1.w >= rect2.x &&
       rect1.y <= rect2.y + rect2.h && rect1.y + rect1.h >= rect2.y){
        return ARC_True;
    }
    return ARC_False;
}

ARC_Bool ARC_Rect_IntersectsPoint(ARC_Rect rect, ARC_Point point){
    if(rect.x <= point.x && rect.x + rect.w >= point.x &&
       rect.y <= point.y && rect.y + rect.h >= point.y){
        return ARC_True;
    }
    return ARC_False;
}

ARC_Bool ARC_FRect_IntersectsPoint(ARC_FRect rect, ARC_Point point){
    if(rect.x <= point.x && rect.x + rect.w >= point.x &&
       rect.y <= point.y && rect.y + rect.h >= point.y){
        return ARC_True;
    }
    return ARC_False;
}

int32_t ARC_Rect_LineIntersects(ARC_Rect *rect, int32_t *x1, int32_t *y1, int32_t *x2, int32_t *y2){
    //TODO: Replace soon
    // return SDL_IntersectRectAndLine((SDL_Rect *) rect, x1, y1, x2, y2);
    return 1;
}

//TODO: position 1px away from colliding, so if velocity is greater than 2px it doesn't have weird gap spacing
//      might need to check diagnals as well, this is a rudamentry implementation
void ARC_FRect_CollideAndSlide(ARC_FRect *rect, ARC_Vector2 *velocity, ARC_FRect *wall){
    ARC_FRect nextRectPosition = {
        .x = rect->x + velocity->x,
        .y = rect->y + velocity->y,
        .w = rect->w,
        .h = rect->h
    };

    //there is no collision, return
    if(!ARC_FRect_Intersects(nextRectPosition, *wall)){
        return;
    }

    nextRectPosition.x = rect->x + velocity->x;
    nextRectPosition.y = rect->y;
    if(ARC_FRect_Intersects(nextRectPosition, *wall)){
        velocity->x = 0;
    }

    nextRectPosition.x = rect->x;
    nextRectPosition.y = rect->y + velocity->y;
    if(ARC_FRect_Intersects(nextRectPosition, *wall)){
        velocity->y = 0;
    }
}