Algorithm Generation flag

This article will provide a set of algorithms for generating flag, and the code is full of positive energy. The previous article was to generate an n-awn star, a pentagram is a kind of awn, so it is not difficult to generate a pentagram image. the flag of the People's Republic of China is flag, the flag face is red, the ratio of length to width is 3:2. Top left yellow Pentagram five, four small star ring arch on the right of a big star, and each has a corner point is the center of the Big star. 1, 4 yellow star aligned, 2, 3 yellow star aligned.

The code is as follows:

H

1 classCpixel5starsredflag: Publicipixelequation2 {3  Public:4 Cpixel5starsredflag ();5 6     Const Char* GetName ()Const7     {8         return "Five Stars Red Flag";9     }Ten  OneUnsignedintCalculatepixel (unsignedintX, unsignedinty); A  -     structStar -     { the         floatPosX; -         floatPosY; -         floatradius; -         floatangle; +     }; -     BOOLIspointinstar (floatXfloatY, star&star); +  A Private: at     floatm_list_sin[5]; -     floatm_list_cos[5]; -  -Star m_list_stars[5]; -};

The first article defines a structural star that determines the position, size, and angle of rotation of a pentagram. You need to set the appropriate value for each star, the code I provide is the parameters I have tried out many times, and does not exactly match the actual.

Cpp

1 Cpixel5starsredflag::cpixel5starsredflag ()2 {3M_width =1680;4M_height =1120;5 6      for(inti =0; I <5; i++)7     {8M_list_sin[i] = Sinf ((I-0.5f)*2*pi/5);9M_list_cos[i] = COSF ((I-0.5f)*2*pi/5);Ten     } One  Am_list_stars[0].POSX = m_width*0.2f; -m_list_stars[0].posy = m_height*0.35f; -m_list_stars[0].radius = m_height*0.1f; them_list_stars[0].angle =0.0f; -  -     floatr = m_list_stars[0].radius *3.0f; -  +m_list_stars[1].POSX = m_list_stars[0].posx + R*COSF (pi/4); -m_list_stars[1].posy = m_list_stars[0].posy + r*sinf (pi/4); +m_list_stars[1].radius = m_list_stars[0].radius*0.5f; Am_list_stars[1].angle =-pi/8; at  -m_list_stars[2].POSX = m_list_stars[0].posx + R*COSF (pi/ A); -m_list_stars[2].posy = m_list_stars[0].posy + r*sinf (pi/ A); -m_list_stars[2].radius = m_list_stars[0].radius*0.5f; -m_list_stars[2].angle =-pi/ -; -  inm_list_stars[3].POSX = m_list_stars[0].posx + R*COSF (-pi/ A); -m_list_stars[3].posy = m_list_stars[0].posy + r*sinf (-pi/ A); tom_list_stars[3].radius = m_list_stars[0].radius*0.5f; +m_list_stars[3].angle = pi/ -; -  them_list_stars[4].POSX = m_list_stars[0].posx + R*COSF (-pi/4); *m_list_stars[4].posy = m_list_stars[0].posy + r*sinf (-pi/4); $m_list_stars[4].radius = m_list_stars[0].radius*0.5f;Panax Notoginsengm_list_stars[4].angle = pi/8; - } the  + BOOLCpixel5starsredflag::ispointinstar (floatXfloatY, star&star) A { the     floati = x-Star.posx; +     floatj = y-Star.posy; -  $     if(I*i + j*j > star.radius*Star.radius) $     { -         return false; -     } the  -     float_s =Sinf (star.angle);Wuyi     float_c =COSF (star.angle); the  - Vec2 P; Wup.x = i*_c-j*_s; -P.Y = i*_s + j*_c; About  $VEC2 listpoints[5]; -      for(unsignedintm =0; M <5; m++) -     { -listpoints[m].x = star.radius*M_list_sin[m]; ALISTPOINTS[M].Y = star.radius*M_list_cos[m]; +     } the  -     BOOLBcenter =true; $      for(unsignedintm =0; M <5; m++) the     { thevec2& v =Listpoints[m]; thevec2& vL1 = listpoints[(M +4)%5]; thevec2& vL2 = listpoints[(M +3)%5]; -vec2& vR1 = listpoints[(M +1)%5]; invec2& vR2 = listpoints[(M +2)%5]; the  the         if(!Ispointinangle (vL2, V, vR2, P)) About         { theBcenter =false; the         } the         Else if(Issameside (vL1, vR1, V, P)) +         { -             return true; the         }Bayi     } the  the     returnBcenter; - } -  theUnsignedintCpixel5starsredflag::calculatepixel (unsignedintX, unsignedinty) the { theUnsignedintRed =0xffff0000; theUnsignedintYellow =0xfffff000; -  the     floati = (float) x; the     floatj = (float) y; the 94      for(unsignedintm =0; M <5; ++m) the     { the         if(Ispointinstar (i, J, M_list_stars[m])) the         {98             returnYellow; About         } -     }101 102     returnRed;103}

base class ipixelequation code See: Why Mathematical image generation tool

On the definition of structural VEC2 and its related functions see: The optimal algorithm for judging points in a triangle on two-dimensional plane

The code is not too elegant between the proportions of the graph, and the actual will be slightly inconsistent. The resulting image is as follows:

corresponding software:

Why Math image Generation tool

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Algorithm Generation flag