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// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.0 (2010/01/01)
#include "KeplerPolarForm.h"
WM5_WINDOW_APPLICATION(KeplerPolarForm);
//----------------------------------------------------------------------------
KeplerPolarForm::KeplerPolarForm ()
:
WindowApplication2("SamplePhysics/KeplerPolarForm", 0, 0, 256, 256,
Float4(1.0f, 1.0f, 1.0f, 1.0f))
{
mSize = GetWidth();
}
//----------------------------------------------------------------------------
bool KeplerPolarForm::OnInitialize ()
{
if (!WindowApplication2::OnInitialize())
{
return false;
}
// Set up the physics module.
mModule.Gravity = 10.0;
mModule.Mass = 1.0;
double time = 0.0;
double deltaTime = 0.01;
double radius = 10.0;
double theta = 0.25*Mathd::PI;
double radiusDot = 0.1;
double thetaDot = 0.1;
mModule.Initialize(time, deltaTime, radius, theta, radiusDot, thetaDot);
const int imax = (int)(mModule.GetPeriod()/deltaTime);
mPositions.resize(imax);
for (int i = 0; i < imax; ++i)
{
double x = 0.5*mSize + 10.0*radius*Mathd::Cos(theta);
double y = 0.5*mSize + 10.0*radius*Mathd::Sin(theta);
mPositions[i] = Vector2d(x, y);
mModule.Update();
time = mModule.GetTime();
radius = mModule.GetRadius();
radiusDot = mModule.GetRadiusDot();
theta = mModule.GetTheta();
thetaDot = mModule.GetThetaDot();
}
// All drawing is in flipped y-values to show the objects in right-handed
// coordinates.
DoFlip(true);
OnDisplay();
return true;
}
//----------------------------------------------------------------------------
void KeplerPolarForm::OnDisplay ()
{
ClearScreen();
const int halfSize = (int)(0.5f*mSize);
const int sizeM1 = (int)(mSize - 1.0f);
// Draw the coordinate axes.
ColorRGB gray(192, 192, 192);
DrawLine(0, halfSize, sizeM1, halfSize, gray);
DrawLine(halfSize, 0, halfSize, sizeM1, gray);
// Draw a ray from the Sun's location to the initial point.
int x = (int)(mPositions[1].X() + 0.5);
int y = (int)(mPositions[1].Y() + 0.5);
DrawLine(halfSize, halfSize, x, y, gray);
// Draw the Sun's location. The Sun is at the origin which happens to
// be a focal point of the ellipse.
SetThickPixel(halfSize, halfSize, 1, ColorRGB(255, 0, 0));
// Draw Earth's orbit. The orbit starts in green, finishes in blue, and
// is a blend of the two colors between.
const int numPositions = (int)mPositions.size();
const float invNumPositions = 1.0f/(float)numPositions;
for (int i = 1; i < numPositions; ++i)
{
float w = i*invNumPositions;
float oneMinusW = 1.0f - w;
unsigned char blue = (unsigned char)(255.0f*oneMinusW);
unsigned char green = (unsigned char)(255.0f*w);
x = (int)(mPositions[i].X() + 0.5);
y = (int)(mPositions[i].Y() + 0.5);
SetPixel(x, y, ColorRGB(0, green, blue));
}
WindowApplication2::OnDisplay();
}
//----------------------------------------------------------------------------
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