WavyPicture.cpp

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/*
 * Copyright (C) 2004 Ivo Danihelka (ivo@danihelka.net)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */
#include "WavyPicture.h"

#include "TimerAgent.h"

#include <math.h>

//-----------------------------------------------------------------
/**
 * Load surface.
 * Default is no waves.
 */
WavyPicture::WavyPicture(const Path &file, const V2 &loc)
    : Picture(file, loc)
{
    m_amp = 0;
    m_periode = m_surface->w;
    m_speed = 0;
}
//-----------------------------------------------------------------
/**
 * Blit entire surface to [x,y].
 * Do vertical waves with phase shift.
 */
void
WavyPicture::drawOn(SDL_Surface *screen)
{
    if (m_amp == 0) {
        Picture::drawOn(screen);
        return;
    }

    //NOTE: Wamp = Wamp_in_orig/2.0
    //NOTE: Wspeed = 1.0/Wspd_in_orig
    SDL_Rect dest_rect;
    SDL_Rect line_rect;
    line_rect.w = m_surface->w;
    line_rect.h = 1;
    SDL_Rect pad;
    pad.h = 1;

    float shift = TimerAgent::agent()->getCycles() * m_speed;

    for (int py = 0; py < m_surface->h; ++py) {
        //NOTE: C99 has lrintf and sinf
        Sint16 shiftX = static_cast<Sint16>(0.5 +
                m_amp * sin(py / m_periode + shift));
        line_rect.x = shiftX;
        line_rect.y = py;
        dest_rect.x = m_loc.getX();
        dest_rect.y = m_loc.getY() + py;
        SDL_BlitSurface(m_surface, &line_rect, screen, &dest_rect);

        pad.x = (shiftX < 0) ? 0 : m_surface->w - shiftX;
        pad.y = py;
        pad.w = abs(shiftX);
        dest_rect.x = m_loc.getX() + pad.x;
        dest_rect.y = m_loc.getY() + py;
        SDL_BlitSurface(m_surface, &pad, screen, &dest_rect);
    }
}

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