To do a good-looking lying cloth

All the difficulty here, or the easy way rather, is to well position the fabric at the beginning, and to make so that it tends to gather in a smaller zone than its dimensions.

Environment

Once more, we will make it easy: a cube (witth rounded edges), lying on the ground:

#declare R = 1;
#declare Cube = union {
    box { < R, 0, R>, < 1-R, 1, 1-R> }
    box { < R, 0, 0>, < 1-R, 1-R, 1> }
    box { < 0, 0, R>, < 1, 1-R, 1-R> }
    cylinder { < R, 0, R>,  < R, 1-R, R>, R }
    cylinder { < R, 0, 1-R>,  < R, 1-R, 1-R>, R }
    cylinder { < 1-R, 0, R>,  < 1-R, 1-R, R>, R }
    cylinder { < 1-R, 0, 1-R>,  < 1-R, 1-R, 1-R>, R }
    sphere { < R, 1-R, R>, R }
    sphere { < R, 1-R, 1-R>, R }
    sphere { < 1-R, 1-R, R>, R }
    sphere { < 1-R, 1-R, 1-R>, R }
    translate -.2*x
}

#declare Obstacle = union {
    plane { y,0 }
    object { Cube }
}

First test

We will reuse WriteClothFile(...) macro from the preceding example, and we will create a rectangular cloth (30 X 50 points):

WriteClothFile("drape.cth", 30, 50, 2/50, 20, 1.5)

simcloth {
    environment Obstacle
    friction 0
    gravity -.5*y
    damping 0.9
    intervals 0.03
    iterations 200
    input "drape.cth"
    mesh_output "drape.msh"
    smooth_mesh on
    uv_mesh on
}

#declare Drap = mesh {
    #include "drape.msh"
    uv_mapping
    texture {
        pigment {
            checker color rgb<1, .5, .2> color rgb<1, .8 ,.4>
            scale <1/10, 3/50, 1>
        }
    }
}

Well... hu... good, but it is not what is called pretty good-looking lying cloth (this one is rather banal...)

Starting position of the cloth

Let's modify the positioning of each point of the cloth, in macro WriteClothFile(...) , by carrying out a rotation of -60 degrees around axis Z, and slightly translating it towards the right, like this:

    #local tempx = -l1/2 + i*nlng;
    #local tempz = -l2/2 + j*nlng;
    #local vtemp = ;
    #local vtemp = vaxis_rotate(vtemp, z, -60);
    #local tempy = ht + (-1+2*rand(st))*nlng*0.1;
    #local vtemp = vtemp + tempy*y + .2*x;
    #write(file, vtemp.x, ",", vtemp.y, ",", vtemp.z, ", 0.0, 0.0, 0.0,\n")

One does not forget "to level up" the cloth, and the starting position can be visualized:

And finally, let the nature... well, ClothRay... do its job:

For the lazy ones, complete script: drape.pov

	The fabric starts lying...
	Some iterations further...
	... and the result.

Obviously, the absence of internal test of collision (fabric against fabric) causes some "errors" (see in bottom of cloth).... But, one can nevertheless obtain more or less satisfactory things.