CG experiment 2nd & 3rd: 2D geometric transformation, cutting, animation, 3D perspective

 

Experiment 21, contraction and Rotation

Note: The key is the transformation matrix,

Contraction matrix:

         doubleb[3][3] = {                   Sx,0, 0,                   0,Sy, 0,                   -xF* Sx + xF, -yF * Sy + yF, 1         };

Rotation matrix:

         doubleb[3][3] = {                   cos(theta),sin(theta), 0,                   -sin(theta),cos(theta), 0,                   xF- xF * cos(theta) + yF * sin(theta), yF - yF * cos(theta) - xF * sin(theta), 1         };

Running result:

Scale down:

Rotation:

Source program:

# Include <iostream> # include <cmath> # include "graphics. H "using namespace STD; const int num = 3; // Number of polygon vertices // matrix multiplication: C = A * B // bring back cvoid mmul (double A [num] [3], double B [3] [3], double C [num] [3]) {for (INT I = 0; I <num; ++ I) {for (Int J = 0; j <3; ++ J) {intelem = 0; for (int K = 0; k <3; ++ K) {ELEM + = A [I] [k] * B [k] [J];} c [I] [J] = ELEM ;}} void zoom (double A [num] [3]) {doublexf; doubleyf; doublesx; doublesy; cout <"Enter the scale:" <Endl; CIN> SX; Sy = SX; cout <"Enter the scale reference point: \ Nx = "; cin> XF; cout <"Y ="; CIN> YF; Double B [3] [3] = {Sx, 0, 0, 0, Sy, 0, -XF * SX + XF,-YF * SY + YF, 1}; doublec [num] [3]; mmul (A, B, C); intgdriver = detect; intgmode = 0; initgraph (& gdriver, & gmode, ""); moveTo (A [num-1] [0], a [num-1] [1]); for (INT I = 0; I <num; ++ I) {lineto (A [I] [0], a [I] [1]);} setcolor (yellow); moveTo (C [num-1] [0], C [num-1] [1]); for (I = 0; I <num; ++ I) {lineto (C [I] [0], C [I] [1]);} system ("pause"); closegraph ();} void turn (double A [num] [3]) {doublexf = 200; doubleyf = 30; doubletheta = ACOs (-1)/2; cout <"Enter the rotation angle: "<Endl; CIN> Theta; cout <" Enter the rotation center: \ Nx = "; CIN> XF; cout <" Y = "; cin> YF; Double B [3] [3] = {cos (theta), sin (theta), 0,-sin (theta), cos (theta), 0, XF-XF * Cos (theta) + YF * sin (theta), YF-YF * Cos (theta)-XF * sin (theta), 1 }; doublec [num] [3]; mmul (A, B, C); intgdriver = detect; intgmode = 0; initgraph (& gdriver, & gmode ,""); moveTo (A [num-1] [0], a [num-1] [1]); For (INT I = 0; I <num; ++ I) {lineto (A [I] [0], a [I] [1]);} setcolor (yellow); moveTo (C [num-1] [0], c [num-1] [1]); for (I = 0; I <num; ++ I) {lineto (C [I] [0], c [I] [1]);} system ("pause"); closegraph ();} int main (INT argc, char ** argv) {INTP [8] = {10, 20,150,150,200, 30, 10, 20}; doublea [num] [3] = {10, 20, 1,150,150, 1, 30, 1 }; // zoom (a); turn (a); return0 ;}

 

2. Cut

Use the library function setviewport to get the View window. The source program is as follows:

#include <stdio.h>#include "graphics.h" #define NUM 3 void Cut(int p[]){         intgdriver = DETECT;         intgmode = 0;         initgraph(&gdriver,&gmode, "");          setviewport(10,20, 100, 100, 1);         drawpoly(1+ NUM, p);         getch();         clearviewport();         closegraph();} int main(){         intp[2 * (NUM + 1)] = {10, 20, 150, 150, 200, 30, 10, 20};         Cut(p);         return0;}

 

Lab 31, animation

The operation result is as follows:

 

Source program:

#include <iostream>#include "graphics.h"using namespace std; int main(int argc,char**argv){    IMAGEimg;    initgraph(500,500);    ellipse(10,10, 90, 300);    getimage(&img,10, 10, 91, 301);     for(int i = 0; i <500 - (90 - 10); i++)    {       cleardevice();       putimage(i,10, &img);       Sleep(10);    }     system("pause");    closegraph();     return 0;}

 

2. 3D fluoroscopy

Displays a perspective projection chart of a cube. The key is transformation matrix:

    double b[DEMENSION][DEMENSION] = {       1,0, 0, 0,       0,1, 0, 0,       0,0, 0, 1 / d,       l,m, 0, 1 + n / d    };

 

Running result:

 

Original program

# DEFINE _ crt_secure_no_warnings # include <iostream> # include "graphics. H "using namespace STD; const int num = 8; // Number of polygon vertices (cube) const int demension = 4; // dimension (n + 1 dimension) // matrix multiplication: c = a * B, bringing back cvoid mmul (double A [num] [demension], doubleb [demension] [demension], double C [num] [demension]) {for (INT I = 0; I <num; ++ I) {for (Int J = 0; j <demension; ++ J) {doubleelem = 0; For (int K = 0; k <demension; ++ K) {ELEM + = A [I] [k] * B [k] [J];} C [I] [J] = ELEM ;}}} // normalize the homogeneous coordinate void standard (double C [num] [demension]) {for (INT I = 0; I <num; ++ I) {for (Int J = 0; j <demension-1; ++ J) {c [I] [J] = C [I] [J]/C [I] [demension-1];} c [I] [demension-1] = 1 ;}// the following code can only draw cubes and 12 sides void draw3d (double array [num] [demension]) {// precision conversion intc [num] [demension]; for (INT I = 0; I <num; ++ I) {for (Int J = 0; j <demension; ++ J) {C [I] [J] = (INT) array [I] [J] ;}} setlinestyle (ps_userstyle, 0xf0f0 ); // The three edges associated with the C [6] vertex are dotted line (C [5] [0], C [5] [1], c [6] [0], C [6] [1]); line (C [6] [0], C [6] [1], c [7] [0], C [7] [1]); line (C [2] [0], C [2] [1], c [6] [0], C [6] [1]); setlinestyle (ps_solid); line (C [0] [0], C [0] [1], c [1] [0], C [1] [1]); line (C [1] [0], C [1] [1], c [2] [0], C [2] [1]); line (C [2] [0], C [2] [1], c [3] [0], C [3] [1]); line (C [3] [0], C [3] [1], c [0] [0], C [0] [1]); line (C [4] [0], C [4] [1], c [5] [0], C [5] [1]); line (C [7] [0], C [7] [1], c [4] [0], C [4] [1]); line (C [0] [0], C [0] [1], c [4] [0], C [4] [1]); line (C [1] [0], C [1] [1], c [5] [0], C [5] [1]); line (C [3] [0], C [3] [1], c [7] [0], C [7] [1]); setlinestyle (ps_solid);} void reflect (double A [num] [demension]) {doubled; // position of the viewpoint on the Z axis (Z =-d) doublel, m, n; // translate the three-dimensional form to the appropriate position l, m, N cout <"Enter the position of the viewpoint on the Z axis:" <Endl; CIN> D; cout <"Enter the appropriate position for translation: "<Endl; CIN> L> m> N; doubleb [demension] [demension] = {, 0, 0, 0, 0, 0, 1/D, L, M, 0, 1 + N/d}; doublec [num] [demension]; mmul (A, B, C ); standard (c); intgdriver = detect; intgmode = 0; initgraph (& gdriver, & gmode, ""); setcolor (yellow); // draw3d (); draw3d (c); sleep (10000); System ("pause"); closegraph ();} int main (INT argc, char ** argv) {freopen ("cin.txt ", "r", stdin); // enter the coordinate of each fixed point of the square doublea [num] [demension]; for (INT I = 0; I <num; ++ I) {for (Int J = 0; j <demension; ++ J) {CIN> A [I] [J] ;}} reflect (a); return0 ;} /* cin.txt: 0 0 0 1300 0 1300 300 300 0 10 300 0 0 1300 300 1300 300 300 300 300 25080 160 1 200 */