Determining the angle and direction to a target

[JeffM2501]

Figures out the angle between player and target and computes the direction of the turn using vector determinant.

direciton.mp4

bool IsRight (Vector2 a, Vector2 b, Vector2 c)
{
    return ((b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x)) > 0;
}

void SpriteView::OnShow(const Rectangle& contentArea)
{
    TargetPos = Vector2Add(TargetPos, Vector2Scale(MovementTools::GetWADSVector(), 200));

    if (IsKeyDown(KEY_LEFT))
        PlayerFacing = Vector2Rotate(PlayerFacing, -90 * GetFrameTime());
    if (IsKeyDown(KEY_RIGHT))
        PlayerFacing = Vector2Rotate(PlayerFacing, 90 * GetFrameTime());

    ClearBackground(Colors::DarkGray);
    BeginMode2D(Camera);
    DrawUtils::DrawGrid2D(Vector2Zero(), (int)RectTools::MaxSize(contentArea)/2, 100, Colors::Gray, Colors::DarkBlue);

    // player and facing
    DrawCircle(PlayerPos.x, PlayerPos.y, 20, BLUE);
    DrawLine(PlayerPos.x, PlayerPos.y, PlayerPos.x + (PlayerFacing.x * 30), PlayerPos.y + (PlayerFacing.y * 30), WHITE);

    // target
    DrawCircle(TargetPos.x, TargetPos.y, 10, RED);

    // line to target
    DrawLine(PlayerPos.x, PlayerPos.y, TargetPos.x, TargetPos.y, YELLOW);

    // vector to target
    Vector2 vecToTarget = Vector2Normalize(Vector2Subtract(TargetPos, PlayerPos));

    float angleToTarget = acosf(Vector2DotProduct(PlayerFacing, vecToTarget)) * RAD2DEG;

    // angle to target
    DrawText(TextFormat("%.1f", angleToTarget), PlayerPos.x, PlayerPos.y - 40, 20, GREEN);

    // direction to target
    if (IsRight(PlayerPos,Vector2Add(PlayerPos,PlayerFacing), TargetPos))
        DrawText("Right", PlayerPos.x - 55, PlayerPos.y - 40, 20, BLUE);
    else
        DrawText("Left", PlayerPos.x - 55, PlayerPos.y - 40, 20, RED);
    
    EndMode2D();

    DrawText(TextFormat("Zoom:%.1f%%", Camera.zoom * 100), 0, (int)contentArea.height - 20, 20, Colors::White);
}