Duet/src/physics.c

#include "duet.h"

void player_position(float angle,
    float *x1, float *y1, float *x2, float *y2, int r)
{
    int x=PLAYER_X, y=DHEIGHT/2;

    float sin, cos;
    sincosf(angle, &sin, &cos);

    if(x1) *x1 = x + sin * r;
    if(y1) *y1 = y + cos * r;

    if(x2) *x2 = x - sin * r;
    if(y2) *y2 = y - cos * r;
}

bool player_collision(game_t const *game)
{
    float x1, y1, x2, y2;
    player_position(game->player_rota, &x1, &y1, &x2, &y2, PLAYER_R);

    for(int i = 0; i < game->rect_count; i++) {
        if(rect_circle_collide(&game->rects[i], x1, y1, PLAYER_SIZE))
            return true;
        if(rect_circle_collide(&game->rects[i], x2, y2, PLAYER_SIZE))
            return true;
    }

    return false;
}

bool rect_circle_collide(rect_t const *r, int cx0, int cy0, int cr)
{
    /* Translate so that rectangle center is (0,0) */
    cx0 -= r->x;
    cy0 -= r->y;

    /* Rotate so that rectangle is flat */
    float sin, cos;
    sincosf(-r->r, &sin, &cos);
    float cx = cx0 * cos + cy0 * sin;
    float cy = -cx0 * sin + cy0 * cos;

    /* Determine point of rectangle closest to center of circle */
    float clx=cx, cly=cy;
    if(clx < -r->w/2) clx = -r->w/2;
    if(clx >  r->w/2) clx =  r->w/2;
    if(cly < -r->h/2) cly = -r->h/2;
    if(cly >  r->h/2) cly =  r->h/2;

    /* Determine whether that point is in the circle */

    return (clx - cx) * (clx - cx) + (cly - cy) * (cly - cy) <= cr * cr;
}

void rect_load(rect_t *r, rectmeta_t const *meta)
{
    r->w = 0;
    r->h = 0;

    switch(meta->shape) {
    case Shape_Square:
        r->w = 0.4;
        r->h = 0.5;
        break;
    case Shape_SmallBar:
        r->w = 0.2;
        r->h = 0.5;
        break;
    case Shape_MediumBar:
        r->w = 0.2;
        r->h = 0.62;
        break;
    case Shape_NormalBar:
        r->w = 0.2;
        r->h = 1.0;
        break;
    case Shape_LongBar:
        r->w = 0.2;
        r->h = 1.15;
        break;
    case Shape_HugeBar:
        r->w = 0.2;
        r->h = 1.5;
        break;
    case Shape_LongVertical:
        r->w = 0.8;
        r->h = 0.2;
        break;
    }

    r->w *= 2 * PLAYER_R;
    r->h *= 2 * PLAYER_R;

    switch(meta->position) {
    case Position_Left:
        if(meta->shape == Shape_Square)
            r->y_init = DHEIGHT/2 - 0.22*CORRIDOR_SIZE;
        else if(meta->shape == Shape_HugeBar)
            r->y_init = DHEIGHT/2 - 0.38*CORRIDOR_SIZE;
        else
            r->y_init = DHEIGHT/2 - CORRIDOR_SIZE/2 + r->h/2;
        break;
    case Position_Right:
        if(meta->shape == Shape_Square)
            r->y_init = DHEIGHT/2 + 0.22*CORRIDOR_SIZE;
        else if(meta->shape == Shape_HugeBar)
            r->y_init = DHEIGHT/2 + 0.38*CORRIDOR_SIZE;
        else
            r->y_init = DHEIGHT/2 + CORRIDOR_SIZE/2 - r->h/2;
        break;
    case Position_Middle:
        r->y_init = DHEIGHT/2;
        break;
    }

    r->y = r->y_init;
    r->opacity = 256;
}

float cubic_ease(float t)
{
    return (t <= 0.5) ? 4 * t * t * t :  1 - 4 * (1 - t) * (1 - t) * (1 - t);
}

void rect_physics(rect_t *r, rectmeta_t const *meta, float absolute_time)
{
    float time = absolute_time - meta->time; /* <= 0 most of the time */

    r->x = PLAYER_X - RECT_SPEED * time;
    r->y = r->y_init;
    r->r = 0;

    /* Action */

    if(meta->action == Action_RotateLeft) {
        float vr = 2.0; /* rad/tempo */
        r->r = -0.3 + time * vr;
    }
    else if(meta->action == Action_RotateRight) {
        float vr = 2.0; /* rad/tempo */
        r->r = 0.3 - time * vr;
    }
    else if(meta->action == Action_Speed1) {
        /* Double speed between -4 and -2 to skip 2 tempi */
        float speeding_period = fminf(2.0, fmaxf(0.0, time + 4.0));
        r->x -= RECT_SPEED * (speeding_period - 2.0);
    }
    else if(meta->action == Action_OuterRotateLeft) {
        float vr = 0.7; /* rad/tempo */
        r->r = time * vr;
    }
    else if(meta->action == Action_OuterRotateRight) {
        float vr = 0.7; /* rad/tempo */
        r->r = -time * vr;
    }
    else if(meta->action == Action_Slide) {
        float amp = 2 * (DHEIGHT/2 - r->y_init);
        /* Nothing happens until -7.5 */
        if(time <= -7.5) {}
        /* Slide to the opposite side between -7.5 and -4.5 */
        else if(time <= -4.5) r->y += amp * cubic_ease((time + 7.5) / 3);
        /* Stay there until -3.5 */
        else if(time <= -3.5) r->y += amp;
        /* Slide back between -3.5 and -0.5 */
        else if(time <= -0.5) r->y += amp * (1 - cubic_ease((time + 3.5) / 3));
        /* Stay there until +0.5 */
        else if(time <= +0.5) {}
        /* Move back between +0.5 and +3.5 */
        else if(time <= +3.5) r->y += amp * cubic_ease((time - 0.5) / 3);
        /* Stay there indefinitely */
        else r->y += amp;
    }
#if 0
    else if(meta->action == Action_Speed2) {
        /* Speed x1.5 permanently */
        r->x -= RECT_SPEED * time * 0.5;
    }
    else if(meta->action == Action_Speed3) {
        // TODO
    }
#endif
    else if(meta->action == Action_Slow) {
        /* Speed x2/3 until they come close enough to you */
        if(time <= -1.0)
            r->x += RECT_SPEED * (time + 1) / 3;
    }

    /* Fadeout */

    if(meta->fadeout == Fadeout_1) {
        /* Reduce opacity to 0 between -4 and -2.5 */
        if(time > -2.5)
            r->opacity = 0;
        else if(time >= -4.0)
            r->opacity = 256 * (1 - (time + 4) / 1.5);
        else
            r->opacity = 256;
    }
    if(meta->fadeout == Fadeout_2) {
        /* Reduce opacity to 0 between -2.5 and -1 */
        if(time > -1)
            r->opacity = 0;
        else if(time >= -2.5)
            r->opacity = 256 * (1 - (time + 2.5) / 1.5);
        else
            r->opacity = 256;
    }
    if(meta->fadeout == Fadeout_3) {
        /* Reduce opacity to 0 between -1 and 0.5 */
        if(time > 0.5)
            r->opacity = 0;
        else if(time >= -1.0)
            r->opacity = 256 * (1 - (time + 1) / 1.5);
        else
            r->opacity = 256;
    }
}