我正在尝试使用以下 Matlab 代码复制以下视觉效果:
% Pumpkin
[X,Y,Z]=sphere(200);
R=1-(1-mod(0:.1:20,2)).^2/12;
x=R.*X; y=R.*Y; z=Z.*R;
c=hypot(hypot(x,y),z)+randn(201)*.03;
surf(x,y,(.8+(0-(1:-.01:-1)'.^4)*.3).*z,c, 'FaceColor', 'interp', 'EdgeColor', 'none')
% Stem
s = [ 1.5 1 repelem(.7, 6) ] .* [ repmat([.1 .06],1,10) .1 ]';
[t, p] = meshgrid(0:pi/15:pi/2,0:pi/20:pi);
Xs = -(.4-cos(p).*s).*cos(t)+.4;
Zs = (.5-cos(p).*s).*sin(t) + .55;
Ys = -sin(p).*s;
surface(Xs,Ys,Zs,[],'FaceColor', '#008000','EdgeColor','none');
% Style
colormap([1 .4 .1; 1 1 .7])
axis equal
box on
material([.6 1 .3])
lighting g
camlight
我正在底层工作,但还没有走得太远(请参阅here以供参考)。我的代码是:
library(pracma)
library(rgl)
sphere <- function(n) {
dd <- expand.grid(theta = seq(0, 2*pi, length.out = n+1),
phi = seq(-pi, pi, length.out = n+1))
with(dd,
list(x = matrix(cos(phi) * cos(theta), n+1),
y = matrix(cos(phi) * sin(theta), n+1),
z = matrix(sin(phi), n+1))
)
}
# Pumpkin
sph<-sphere(200)
X<-sph[[1]]
Y<-sph[[2]]
Z<-sph[[3]]
R<- 1-(1-seq(from=0, to=20,by=0.1))^2/12
x<-R * X
y<-R * Y
z<-Z * R
c<-hypot(hypot(x,y),z)+rnorm(201)*0.3
persp3d(x,y,(0.8+(0-seq(from=1, to=-1, by=-0.01)^4)*0.3)*z,col=c)
它给了我以下内容。
我现在的代码出了什么问题?建议修复什么?
正如 @billBokeey 提到的,周期性缩放因子缺少
mod
模运算符函数。
此外,z 轴
0.8 + (0-seq(from=1, to=-1, by=-0.01)^4) * 0.3
上的缩放与 sphere
函数的输出不太相符。 Z[1,]
来代替 seq(from=1, to=-1, by=-0.01)
。phi = seq(-pi, pi, length.out = n+1))
应该是 seq(-pi/2, pi/2, length.out = n+1))
。
最后,颜色
c
需要转换为RGB代码persp3d
。
这是下面代码的结果。
library(rgl)
sphere <- function(n) {
dd <- expand.grid(theta = seq(0, 2*pi, length.out = n+1),
phi = seq(-pi/2, pi/2, length.out = n+1))
with(dd,
list(x = matrix(cos(phi) * cos(theta), n+1),
y = matrix(cos(phi) * sin(theta), n+1),
z = matrix(sin(phi), n+1))
)
}
# Unit ball
sph <- sphere(200)
X <- sph[[1]]
Y <- sph[[2]]
Z <- sph[[3]]
# scaling
R <- 1 - (1 - seq(from=0, to=20, by=0.1) %% 2) ^ 2 / 12 # Modulo Operator %%
R2 <- 0.8 + (0 - seq(from=1, to=-1, by=-0.01)^4)*0.2 # didn't match with the order of z from sphere function
#R2 <- 0.8 - Z[1,]^4 * 0.2
x <- R * X # scale rows for wavy side
y <- R * Y # scale rows for wavy side
z <- t(R2 * t(Z)) # scale columns by transpose for flat oval shape
# color according to distance to [0,0,0]
hypot_3d <- function(x, y, z) {
return(sqrt(x^2 + y^2 + z^2))
}
c_ <- hypot_3d(x,y,z) + rnorm(201) * 0.03
color_palette <- terrain.colors(20) # color look-up table
col <- color_palette[ as.numeric(cut(c_, breaks = 20)) ] # assign color to 20 levels of c_
persp3d(x, y, z, color = col, aspect=FALSE)
% 南瓜
使用 .* 时出错 矩阵尺寸必须一致。
南瓜_3 中的错误(第 7 行) x=R.*X; y=R.*Y; z=R.*Z;