Question

我为正在玩的3D图形制作了这个三角形填充物，但它只能在平面上画一条线吗？用于sdl2。

void ftri(SDL_Renderer* r,int x1,int y1,int x2,int y2,int x3,int y3)
{
    int yt,xt;
    if(y1 > y2){yt = y1;y1 = y2;y2 = yt;xt = x1;x1 = x2;x2 = xt;}
    if(y2 > y3){yt = y2;y2 = y3;y3 = yt;xt = x2;x2 = x3;x3 = xt;}
    if(y3 > y1){yt = y3;y3 = y1;y1 = yt;xt = x3;x3 = x1;x1 = xt;}
    float s1,s2;
    s1 = (float(x3)-float(x1))/(float(y3)-float(y1));
    if(y1==y2)
        SDL_RenderDrawLine(r,x1,y1,x2,y1);
    else
    {
        s2 = (float(x2)-float(x1))/(float(y2)-float(y1));
        for (int y = y1;y < y2;y++)
            SDL_RenderDrawLine(r,s1*float(y),y,s2*float(y),y);
    }
    if(y2==y3)
        SDL_RenderDrawLine(r,x2,y2,x3,y2);
    else
    {
        s2 = (float(x3)-float(x2))/(float(y3)-float(y2));
        for (int y = y2;y < y3;y++)
            SDL_RenderDrawLine(r,s1*float(y),y,s2*float(y),y);
    }
}

Answer 1

这更好吗？

void ftri(SDL_Renderer* r,int x1,int y1,int x2,int y2,int x3,int y3)
{
    int yt,xt;
    if(y1 < y2){yt = y1;y1 = y2;y2 = yt;xt = x1;x1 = x2;x2 = xt;}
    if(y2 < y3){yt = y2;y2 = y3;y3 = yt;xt = x2;x2 = x3;x3 = xt;}
    if(y3 < y1){yt = y3;y3 = y1;y1 = yt;xt = x3;x3 = x1;x1 = xt;}
    float s1,s2;
    s1 = (float(y3)-float(y1))/(float(x3)-float(x1));
    if(y1==y2)
        SDL_RenderDrawLine(r,x1,y1,x2,y1);
    else
    {
        s2 = (float(y2)-float(y1))/(float(x2)-float(x1));
        for (int y = y1;y < y2;y++)
            SDL_RenderDrawLine(r,float(y-y1)/s1+x1,y,float(y-y1)/s2+x1,y);
    }
    if(y2==y3)
        SDL_RenderDrawLine(r,x2,y2,x3,y2);
    else
    {
        s2 = (float(y3)-float(y2))/(float(x3)-float(x2));
        for (int y = y2;y < y3;y++)
            SDL_RenderDrawLine(r,float(y-y1)/s1+x1,y,float(y-y2)/s2+x2,y);
    }
}

为什么我的3D图形三角形填充物只能画一条线？

1 个答案: