模板: 扫描线 Scanline Rendering
Scanline Rendering
扫描线
Brief Introduction
Scanline rendering (also scan line rendering and scan-line rendering) is an algorithm for visible surface determination, in 3D computer graphics, that works on a row-by-row basis rather than a polygon-by-polygon or pixel-by-pixel basis. All of the polygons to be rendered are first sorted by the top y coordinate at which they first appear, then each row or scan line of the image is computed using the intersection of a scanline with the polygons on the front of the sorted list, while the sorted list is updated to discard no-longer-visible polygons as the active scan line is advanced down the picture.
Algorithm
To be updated
Template Code
#include <cstdio>
#include <cstring>
#define LL long long
#define MAXN 100005
struct node{
LL sum,tag;
}sgt[MAXN<<2];
int M;
int a[MAXN];
void built(int n){
for(M=1;M<n+2;M<<=1);
memset(sgt+M,0,M*sizeof(sgt[0]));
for(int i=1;i<=n;i++)
sgt[M+i].sum=a[i];
for(int i=M-1;i;i--)
sgt[i].sum=sgt[i<<1].sum+sgt[i<<1|1].sum;
}
void modify(int l,int r,LL del){
LL len=1,lc=0,rc=0;
for(l=l+M-1,r=r+M+1;l^r^1;l>>=1,r>>=1,len<<=1){
if(~l&1) sgt[l+1].tag+=del, lc+=len;
if(r&1) sgt[r-1].tag+=del, rc+=len;
sgt[l>>1].sum+=del*lc;
sgt[r>>1].sum+=del*rc;
}
for(lc+=rc,l>>=1;l;l>>=1)
sgt[l].sum+=del*lc;
}
LL query(int l,int r){
LL res=0,len=1,lc=0,rc=0;
for(l=l+M-1,r=r+M+1;l^r^1;l>>=1,r>>=1,len<<=1){
if(~l&1) res+=sgt[l+1].sum+sgt[l+1].tag*len, lc+=len;
if(r&1) res+=sgt[r-1].sum+sgt[r-1].tag*len, rc+=len;
res+=sgt[l>>1].tag*lc;
res+=sgt[r>>1].tag*rc;
}
for(lc+=rc,l>>=1;l;l>>=1)
res+=sgt[l].tag*lc;
return res;
}
int main(){
int n,m;
scanf("%d %d", &n, &m);
for(int i=1;i<=n;i++)
scanf("%d", &a[i]);
built(n);
for(int i=1;i<=m;i++){
int opt,x,y;
scanf("%d %d %d", &opt, &x, &y);
if(opt==1){
int k;
scanf("%d", &k);
modify(x,y,k);
}
else{
printf("%lld\n", query(x,y));
}
}
return 0;
}
本人博客
leachim.wang
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https://github.com/Michaelwmx/
上面有我平时写的代码和模板。
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