3d cad graphics project - pdf

GRAPHICS IN CAD

PROJECT – 2 11/23/09

SASI BEERA (#3576-3829)

ANIRUDH PASUPULETI (#3678-2070)

Introduction

In this project, the “Basic3DTools” and “HiddenLineRemoval” concepts are used as a

basis. To define and manipulate 3D objects, a series of classes are used in the code.

Careful studying and reviewing the class C3DShapes and also the C3DShapes functions

by the classes CCylShapes and CExtrudeShapes approaches the project solution. The

original code from Basic3DTools and HiddenLineRemoval is modified at will to achieve

the desired outcome.

Description and Features

The game plan of this project is to build a farm scene and eventually fill colors and

remove hidden lines when viewed from a vantage point. The trees are „chopped down‟

from the example problem and a conical structure is added to the silo. A car is present in

front of the barn, which can be moved, linearly in the forward and backward directions.

At any moment the user can get back to the initial image by simply selecting the New

button, which is provided. All the polygons are filled later, that is, appear to be solid

structures and are filled with the given colors. The hidden features of the polygons are

removed and thus show a much-improved ability to render the farm scene as the car

moves in and out of the barn and as the mouse is used to manipulate the view.

Adding the ability to change the viewing distance while viewing the scene further

develops the project. The „I‟ and „O‟ keys are used to move „in‟ or „out‟ of the scene and

also mouse control is provided to perform this operation.

Additionally, an animation is provided in the farm scene by considering the silo (with its

top) to be a rocket.

A launch button „L‟ is provided to lift off and fly the silo rocket through a simple

parabolic trajectory ending by entering and stopping in the barn. A default view position

is provided. By pressing „S‟ the silo stops traversing. Finally, „R‟ resets the position of

the silo by bringing it back to its home position.

This animation can also done by using the Drop-down menu provided on the top. Three

different buttons are provided – Launch, Stop, Reset to perform the same operations as

above.

A dialog box is provided which allows the viewer to input a specific viewing location in

terms of x, y, and z coordinate values.

This box can be found by clicking the View button provided on the top. After entering

the desired values, the user will then be placed at the specified position and will be

looking directly at the origin.

Strategy behind CConeShapes class

A similar logic used in CCylinderShapes is incorporated here in CConeShapes class. The

variables, which govern the generation of cylinders, as well as cones, are nsegs, radius

and length. These are used to sequentially define nlines, npoints, ncurves and npolygons.

A cylinder, for example, has 8 segments and a certain radius and length.

This results in 8 lines, 16 points (8 each on top and bottom curves), 2 curves (top and

bottom) and 10 polygons (8 plus 2 curves). Similarly, a cone having 8 segments and a

certain radius and length, results in 8 lines, 9 points (8 on the bottom and the apex point

on top), 1 curve (bottom) and 9 polygons (8 plus 1 curve). Hence the strategy of

CConeShapes class is so characterized.

The code for CConeShapes class is as follows:

void CConeShapes::AdjustConeShape (int nseg, double Radius, double Length)

{

m_BasePoint.Adjust3DPoint(0, 0, 0);

double Phi=0;

double fnseg = nseg;

double DPhi=(2.*3.14158)/fnseg;

int i;

for (i = 0; i<nseg; i++)

{

double xp = Radius * cos(Phi);

double yp = Radius * sin(Phi);

double zp = 0;

m_ShapePoints[i].Adjust3DPoint(xp,yp,zp);

Phi+=DPhi;

}

double xp = 0;

double yp = 0;

double zp = -Length;

m_ShapePoints[nseg].Adjust3DPoint(xp,yp,zp);

m_NumPoints = nseg+1;

m_NumPolygons = nseg+1;

m_NumPointsPerPolygon[0] = nseg;

for (i=0; i<nseg; i++){m_PolygonPointMatrix[0][i] = i;}

for (i=0; i<nseg-1; i++){

m_NumPointsPerPolygon[i+1]=3;

m_PolygonPointMatrix[i+1][2]=i;

m_PolygonPointMatrix[i+1][1]=i+1;

m_PolygonPointMatrix[i+1][0]=nseg;

}

m_NumPointsPerPolygon[nseg]=3;

m_PolygonPointMatrix[nseg][0]=nseg;

m_PolygonPointMatrix[nseg][1]=0;

m_PolygonPointMatrix[nseg][2]=nseg-1;

}

void CConeShapes::Move (double Mvx, double Mvy, double Mvz)

{C3DShapes::Move(Mvx, Mvy, Mvz);}

void CConeShapes::Dmove (double DMvx, double DMvy, double DMvz)

{C3DShapes::Dmove(DMvx, DMvy, DMvz);}

void CConeShapes::ShowConeShape(CDC* pDC,double m_zvp)

{

C3DShapes::Show3DShape (pDC,m_zvp);

}

void CConeShapes::GRotateX(double Theta, C3DPoints RPoint)

{

C3DShapes::GRotateX(Theta, RPoint);

}

void CConeShapes::GRotateY(double Theta, C3DPoints RPoint)

{

C3DShapes::GRotateY(Theta, RPoint);

}

void CConeShapes::GRotateZ(double Theta, C3DPoints RPoint)

{

C3DShapes::GRotateZ(Theta, RPoint);

}

void CConeShapes::RotateX(double Theta)

{

C3DShapes::RotateX(Theta);

}

void CConeShapes::RotateY(double Theta)

{

C3DShapes::RotateY(Theta);

}

void CConeShapes::RotateZ(double Theta)

{

C3DShapes::RotateZ(Theta);

}

};

Approach to Polygon fill routine for 3D shapes:

Here, the polygons are filled using the following code along with this additional

command:

pDC->Polygon(PolyPts,m_NumPnts);

For showing the polygons, the Show3DPolygons is defined. Initially, the structure of

each polygon is characterized by the governing variables. The NumPnts define the

number of points to be considered for constructing the polygon. Then the base point is

delineated for each polygon and also the polygons are thus created.

Listing of Show3DPolygons code:

void C3DPolygons::Show3DPolygon(CDC* pDC, C3DPoints BasePoint, double zvp)

{

double PolyVisible;

CPoint PolyPts[25];

m_PointArray[m_NumPnts] = m_PointArray[0];

for (int i = 0; i < m_NumPnts; i++)

{

double x = BasePoint.m_x + m_PointArray[i].m_x;

double y = BasePoint.m_y + m_PointArray[i].m_y;

double z = BasePoint.m_z + m_PointArray[i].m_z;

double xp1 = BasePoint.m_x + m_PointArray[i+1].m_x;

double yp1 = BasePoint.m_y + m_PointArray[i+1].m_y;

double zp1 = BasePoint.m_z + m_PointArray[i+1].m_z;

double xds = x/(1.-z/zvp);

double yds = y/(1.-z/zvp);

double xdf = xp1/(1.-zp1/zvp);

double ydf = yp1/(1.-zp1/zvp);

if (i==0)

{

double xp2 = BasePoint.m_x + m_PointArray[i+2].m_x;

double yp2 = BasePoint.m_y + m_PointArray[i+2].m_y;

double zp2 = BasePoint.m_z + m_PointArray[i+2].m_z;

double xdf2 = xp2/(1.-zp2/zvp);

double ydf2 = yp2/(1.-zp2/zvp);

double a = xdf-xds;

double b = ydf-yds;

double c = xdf2-xds;

double d = ydf2-yds;

PolyVisible = (a*d-b*c)/abs(a*d-b*c);

}

xds = xds + 320;

yds = -yds +240;

xdf = xdf + 320;

ydf = -ydf + 240;

if(PolyVisible > 0)

{

pDC->MoveTo(int(xds),int(yds));

pDC->LineTo(int(xdf),int(ydf));

PolyPts[i].x = xds;

PolyPts[i].y = yds;

}

//pDC->Polygon(PolyPts,m_NumPnts);

}

pDC->Polygon(PolyPts,m_NumPnts);

}

};

Miscellaneous discussion:

The development of Version 2 of this program is continued to better remove

hidden features. Then the objects are „shown‟ in the order of their base point z

distances.

The generated image thus shows much improved (but probably not perfect) ability

to render the farm scene as the car moves in and out of the barn and as the mouse

is used to manipulate the view.

Additionally, an animation is provided in the farm scene by considering the silo

(with its top) to be a rocket.


parabolic trajectory ending by entering and stopping in the barn. A default view

position is provided. By pressing „S‟ the silo stops traversing. Finally, „R‟ resets

the position of the silo by bringing it back to its home position.

A dialog box is provided which allows the viewer to input a specific viewing

location in terms of x, y, and z coordinate values.

This box can be found by clicking the View button provided on the top. After

entering the desired values, the user will then be placed at the specified position

and will be looking directly at the origin.

“Print Screens” for each item:

Figure 1: Wireframe model- Item 1

Figure 2: Item 2 of the farm-scene

Figure 3: Item 3 of the farm-scene (vantage point)

Figure 4: Item 3 (developed)

Figure 5: Item 3 (hidden features removed)

Figure 6: Item 6 (cone of the silo launched)

Figure 7: Item 6 (cone of the silo traversing the trajectory)

Figure 8: Item 6 (cone changing its angle gradually)

Figure 9: Item 6 (cone of the silo targeting the barn)

Figure 10: Item 6 (the barn is „bombed‟)

X = 1000,y= 0, z= 0;

X= 1000, y = 1000, z= 0;

X= 1000, y = -1000, z= 0;

Description of approach to displaying most distant objects last to

enhance hidden part removal:

Initially, the distances of base-points of each shape- barn, cylinder, cone, and vehicle are

stored using the variables- ZExtrudeShape1, ZCylShape, ZConeShape1, ZSimpleVehicle.

Then by applying the following logic, the process of displaying most distant objects last

to enhance hidden part removal is carried out:

if (ZExtrudeShape1>ZCylShape>ZSimpleVehicle)

{

pDC->SelectObject(&m_YellowBrush);

ViewConeShape1.ShowConeShape(pDC,zvp);

ViewSimpleVehicle.ShowExtrudeShape(pDC,zvp);

pDC->SelectObject(&m_RedBrush);

for(int icnt=0; icnt<1; icnt++){

ViewCylShapeArray[icnt].ShowCylShape(pDC,zvp);

}

In this loop, the logical idea is that the z-distances that are stored are compared so as to

eventually operate the process of displaying the barn, cylinder, cone and vehicle in

decreasing order.

The listing of OnDraw code:

void CViewFarmSceneHView::OnDraw(CDC* pDC)

{

CViewFarmSceneHDoc* pDoc = GetDocument();

ASSERT_VALID(pDoc);

if (!pDoc)

return;

ViewSimpleVehicle = pDoc->SimpleVehicle;

ViewExtrudeShape1 = pDoc->ExtrudeShape1;

ViewSimpleVehicle = pDoc->SimpleVehicle;

ViewConeShape1 = pDoc->ConeShape1[0];


ViewCylShapeArray[icnt] = pDoc->CylShapeArray[icnt];

}

C3DPoints Origin;

Origin.Adjust3DPoint(0,0,0);

ViewExtrudeShape1.GRotateY(HorizAngle, Origin);

ViewExtrudeShape1.GRotateX(VertAngle, Origin);

ViewSimpleVehicle.GRotateY(HorizAngle, Origin);

ViewSimpleVehicle.GRotateX(VertAngle, Origin);

ViewConeShape1.GRotateY(HorizAngle, Origin);

ViewConeShape1.GRotateX(VertAngle, Origin);


ViewCylShapeArray[icnt].GRotateY(HorizAngle, Origin);

ViewCylShapeArray[icnt].GRotateX(VertAngle, Origin);

}

double ZExtrudeShape1 = ViewExtrudeShape1.m_BasePoint.m_z;

double ZCylShape = ViewCylShapeArray[0].m_BasePoint.m_z;

double ZConeShape1 = ViewConeShape1.m_BasePoint.m_z;

double ZSimpleVehicle = ViewSimpleVehicle.m_BasePoint.m_z;

if (ZExtrudeShape1<ZCylShape<ZSimpleVehicle)

{


ViewExtrudeShape1.ShowExtrudeShape(pDC,zvp);



}




}

if (ZExtrudeShape1>ZCylShape>ZSimpleVehicle)

{







}

ViewExtrudeShape1.ShowExtrudeShape(pDC,zvp);

}

}

User’s instructions:

By clicking the executable program (version 1) that will open the 3-D farm scene.

By clicking and holding the left mouse button and eventually moving it, the user

can view the scene from desired direction.

Next by hitting the Up and Down keys the car in the farm scene can be moved

away and towards the barn respectively. Clicking the New button and hitting the

„N‟ key will return to the initial image.

For the Version 2, the polygon projections are „filled‟ than drawn. It opens with

the same scene but now with the filled polygons of the barn and silo colored red

and the car and the top of the silo colored yellow.

Again clicking the New button and hitting the „N‟ key will return to the initial

image.

The development of Version 2 of this program is continued to better remove

hidden features. Then the objects are „shown‟ in the order of their base point z

distances.

The generated image thus shows much improved (but probably not perfect) ability

to render the farm scene as the car moves in and out of the barn and as the mouse

is used to manipulate the view.

Adding the ability to change the viewing distance while viewing the scene further

develops the Version 2. Using „I‟ and „O‟ keys to move „in‟ or „out‟ can do this.

A mouse control is provided as well to perform this operation. Hitting the „N‟ key

and selecting the New button will bring it back to the initial image.

Additionally, an animation is provided in the farm scene by considering the silo

(with its top) to be a rocket.


parabolic trajectory ending by entering and stopping in the barn. A default view

position is provided. By pressing „S‟ the silo stops traversing. Finally, „R‟ resets

the position of the silo by bringing it back to its home position.

This animation can also done by using the Drop-down menu provided on the top.

Three different buttons are provided – Launch, Stop, Reset to perform the same

operations as above.

A dialog box is provided which allows the viewer to input a specific viewing

location in terms of x, y, and z coordinate values.

This box can be found by clicking the View button provided on the top. After

entering the desired values, the user will then be placed at the specified position

and will be looking directly at the origin.

3d cad graphics project - pdf

Technology

double length

double radius

double fnseg

c3dpoints basepoint

double zvp

double phi

double zp1

double xp2