Code's here:
unsigned RGB(unsigned char R, unsigned char G, unsigned B){
return (R << 16) | (G << 8) | B;
}
void put_pixel(SDL_Surface * s, unsigned x, unsigned y, unsigned color){
unsigned long * pixels = (unsigned long *)s->pixels;
if(x >= s->w || y >= s->h)
return;
pixels[x+y*s->w] = color;
}
void draw_line(SDL_Surface * s, int x0, int y0, int x1, int y1, unsigned color){
int x, y;
int xproj = x1-x0, yproj = y1-y0, pm;
if(!xproj && !yproj)
return;
if(abs(xproj) > abs(yproj)){
pm = xproj >= 0 ? 1 : -1;
for(x = 0; x != xproj; x += pm){
y = rint(x* yproj/(double)xproj);
put_pixel(s, x0 + x, y0 + y, color);
}
}else{
pm = yproj >= 0 ? 1 : -1;
for(y = 0; y != yproj; y += pm){
x = rint(y* xproj/(double)yproj);
put_pixel(s, x0+x, y0+y, color);
}
}
}
float sign(int x0, int y0, int x1, int y1, int x2, int y2){
return (x0 - x2) * (y1 - y2) - (x1 - x2) * (y0 - y2);
}
int ptintr(int sx, int sy, int x0, int y0, int x1, int y1, int x2, int y2){
int b1, b2, b3;
b1 = sign(sx, sy, x0, y0, x1, y1) < 0.0f ? 1 : 0;
b2 = sign(sx, sy, x1, y1, x2, y2) < 0.0f ? 1 : 0;
b3 = sign(sx, sy, x2, y2, x0, y0) < 0.0f ? 1 : 0;
if((b1 == b2) && (b2 == b3))
return 1;
return 0;
}
float get_dist(int x1, int y1, int x2, int y2){
int xproj = x2-x1;
int yproj = y2-y1;
float dist = sqrt(pow(xproj, 2) + pow(yproj, 2));
return dist;
}
unsigned char getR(unsigned c){
return (c >> 16) & 0xFF;
}
unsigned char getG(unsigned c){
return (c >> 8) & 0xFF;
}
unsigned char getB(unsigned c){
return c & 0xFF;
}
void draw_ftriangle(SDL_Surface * s, int x0, int y0, unsigned c0, int x1, int y1, unsigned c1, int x2, int y2, unsigned c2){
int x;
signed d0, d1, d2;
unsigned R, G, B, color;
int ymin = min(y0, min(y1, y2));
int xmin = min(x0, min(x1, x2));
int ymax = max(y0, max(y1, y2));
int xmax = max(x0, max(x1, x2));
draw_line(s, x0, y0, x1, y1, color);
draw_line(s, x1, y1, x2, y2, color);
draw_line(s, x0, y0, x2, y2, color);
for(; ymin < ymax; ymin++)
for(x=xmin; x < xmax; x++)
if(ptintr(x, ymin, x0, y0, x1, y1, x2, y2)){
d0 = get_dist(x, ymin, x0, y0);
d1 = get_dist(x, ymin, x1, y1);
d2 = get_dist(x, ymin, x2, y2);
R = d0+d1+d2 == 1 ? getR(c0)*d0 + getR(c1)*d1 + getR(c2)*d2 :
(getR(c0)*d0 + getR(c1)*d1 + getR(c2)*d2)/(d0+d1+d2);
G = d0+d1+d2 == 1 ? getG(c0)*d0 + getG(c1)*d1 + getG(c2)*d2 :
(getG(c0)*d0 + getG(c1)*d1 + getG(c2)*d2)/(d0+d1+d2);
B = d0+d1+d2 == 1 ? getB(c0)*d0 + getB(c1)*d1 + getB(c2)*d2 :
(getB(c0)*d0 + getB(c1)*d1 + getB(c2)*d2)/(d0+d1+d2);
color = RGB(R, G, B);
put_pixel(s, x, ymin, color);
}
}
And I call function draw_ftriangle like this:
draw_ftriangle(surface, 100, 100, RGB(255, 0, 0),
235, 150, RGB(0, 255, 0),
64, 254, RGB(0, 0, 255));
I'm not sure, but I think the problem is here:
R = d0+d1+d2 == 1 ? getR(c0)*d0 + getR(c1)*d1 + getR(c2)*d2 :
(getR(c0)*d0 + getR(c1)*d1 + getR(c2)*d2)/(d0+d1+d2);
G = d0+d1+d2 == 1 ? getG(c0)*d0 + getG(c1)*d1 + getG(c2)*d2 :
(getG(c0)*d0 + getG(c1)*d1 + getG(c2)*d2)/(d0+d1+d2);
B = d0+d1+d2 == 1 ? getB(c0)*d0 + getB(c1)*d1 + getB(c2)*d2 :
(getB(c0)*d0 + getB(c1)*d1 + getB(c2)*d2)/(d0+d1+d2);
Please help me to find a problem!