138 lines
4.4 KiB
C
138 lines
4.4 KiB
C
#include "face.h"
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#include "zbuffer.h"
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#include <stdbool.h>
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#include <gint/display.h>
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#define min(x,y) (x<y?x:y)
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#define max(x,y) (x>y?x:y)
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#define abs(x) (x>0?x:-x)
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static bool sens_horaire(FE_face const * face)
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{
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int area = 0;
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area+=face->s1->translated.x*face->s2->translated.y;
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area-=face->s2->translated.x*face->s1->translated.y;
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area+=face->s2->translated.x*face->s3->translated.y;
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area-=face->s3->translated.x*face->s2->translated.y;
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area+=face->s3->translated.x*face->s1->translated.y;
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area-=face->s1->translated.x*face->s3->translated.y;
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return (area < 0);
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}
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// gestion des lignes
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typedef struct line line;
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struct line
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{
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int x,y,z;
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int dx,dy,dz;
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bool no_line; // si les deux points sont confondus
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};
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static void set_line(line* segment,FE_point const * s1, FE_point const * s2)
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{
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segment->x=s1->translated.x;
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segment->y=s1->translated.y;
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segment->z=s1->translated.z;
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segment->dx=s2->translated.x-s1->translated.x;
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segment->dy=s2->translated.y-s1->translated.y;
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segment->dz=s2->translated.z-s1->translated.z;
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segment->no_line=(segment->dx==0&&segment->dy==0);
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}
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static bool get_x(int y, line const * segment, int * x)
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{
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y-=segment->y;
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if (y<0 && segment->dy>0)
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return false;
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if (y>0 && segment->dy<0)
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return false;
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if (abs(y)>abs(segment->dy))
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return false;
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if (segment->dy!=0)
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*x=segment->x+(y*segment->dx)/segment->dy;
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else if (y==0)
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*x=segment->x+segment->dx;
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else
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return false;
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return true;
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}
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void FE_draw_face(FE_face const * face)
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{
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if (sens_horaire(face)!=face->visible)
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return;
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if (face->s1->translated.x<0 && face->s2->translated.x<0 && face->s3->translated.x<0)
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return;
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if (face->s1->translated.x>127 && face->s2->translated.x>127 && face->s3->translated.x>127)
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return;
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if (face->s1->translated.y<0 && face->s2->translated.y<0 && face->s3->translated.y<0)
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return;
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if (face->s1->translated.y>63 && face->s2->translated.y>63 && face->s3->translated.y>63)
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return;
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if (face->s1->translated.z<=0 && face->s2->translated.z<=0 && face->s3->translated.z<=0)
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return;
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line cotes[3];
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set_line(&cotes[0],face->s1,face->s2);
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set_line(&cotes[1],face->s1,face->s3);
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set_line(&cotes[2],face->s2,face->s3);
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if (cotes[0].no_line||cotes[1].no_line||cotes[2].no_line)
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return;
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const int xmin=min(face->s1->translated.x,min(face->s2->translated.x,face->s3->translated.x));
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const int xmax=max(face->s1->translated.x,max(face->s2->translated.x,face->s3->translated.x));
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const int ymin=max(min(face->s1->translated.y,min(face->s2->translated.y,face->s3->translated.y)),0);
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const int ymax=min(max(face->s1->translated.y,max(face->s2->translated.y,face->s3->translated.y)),63);
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const int xAB=face->s2->translated.x-face->s1->translated.x, yAB=face->s2->translated.y-face->s1->translated.y;
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const int xAC=face->s3->translated.x-face->s1->translated.x, yAC=face->s3->translated.y-face->s1->translated.y;
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const int diviseur_commun=(xAB*yAC-yAB*xAC); //(multiplier par 10000)
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const int fact_1=(10000*yAC)/diviseur_commun, fact_2=(10000*xAC)/diviseur_commun;
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const int fact_3=(10000*xAB)/diviseur_commun, fact_4=(10000*yAB)/diviseur_commun;
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for (int ty=ymin; ty<=ymax; ty++)
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{
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int tx1,tx2;
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// tx1
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for (int t=0;t<3;t++)
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{if (get_x(ty,&cotes[t],&tx1)) break;}
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for (int t=0;t<3;t++)
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{if (get_x(ty,&cotes[t],&tx2)&&tx1!=tx2) break;}
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const int txmin=max(min(tx1,tx2),0), txmax=min(max(tx1,tx2),127);
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for (int tx=txmin; tx<=txmax; tx++)
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{
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int vx,vy,vz;
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int xcalc=tx-face->s1->translated.x, ycalc=ty-face->s1->translated.y;
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vx=(xcalc*fact_1-ycalc*fact_2)/1250;
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vy=(ycalc*fact_3-xcalc*fact_4)/1250;
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vz=face->s1->translated.z + (vx*cotes[0].dz + vy*cotes[1].dz)/8;
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if (FE_zbuffer_set_dist(tx,ty,vz))
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dpixel(tx,ty,3*FE_get_pixel(face->texturenum,vx,vy));
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}
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}
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// x=Det(AM,AC)/det(AB,AC)
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// y=det(AM,AB)/det(AC,AB)
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// x=(xAM*yAC-yAM*xAC)/(xAB*yAC-yAB*xAC)
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// y=(xAM*yAB-yAM*xAB)/(xAC*yAB-yAC*xAB)
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// soit diviseur_commun = (xAB*yAC-yAB*xAC)
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// x=xAM*yAC/diviseur_commun-yAM*xAC/diviseur_commun
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// y=yAM*xAB/diviseur_commun-xAM*yAB/diciseur_commun
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} |