Mapping procedural (Perlin Noise) textures onto a sphere divided into squarish facets. the 6 surfaces of a cube are mapped onto the sphere.
from cubicsphere.o2bas / shapes.inc
'GLOBE
if not csface
csface=CompileList
CubicFace 8
glEndList
end if
glPushMatrix
glTranslatef -1.0,0.,-6.0
glRotatef ang1,0,1,0
'RedShinyMaterial.act
whiteMaterial.act
glEnable GL_TEXTURE_2D
glBindTexture GL_TEXTURE_2D,t2'texn(3)
glCallList csface
glRotatef 90.0,0,1,0
glCallList csface
glRotatef 90.0,0,1,0
glCallList csface
glRotatef 90.0,0,1,0
glCallList csface
glRotatef 90.0,1,0,0
glCallList csface
glRotatef 180.0,1,0,0 'top
glCallList csface
glPopMatrix
--->
sub CubicFace(sys n)
====================
sys i,j
float u,v,w,x,y,z,sc,su,sv
sc=1./n
su=sc
sv=sc
float w1,w2,x1,y1,z1,x2,y2,z2,u1,u2,v1,v2
y=-1.0
w=1/sqr(3)
y1=y*w
v=0.
v1=v
for j=-n to <n
x=-1.0
u= 0.
u1=u
if v1+sv<0 or v1+sv>1.0 then sv=-sv
v2=v1+sv
glBegin GL_QUAD_STRIP
for i=-n to n
w1=1/sqr(x*x+y*y+1.0) '1/(distance to centre of cube)
y+=sc
w2=1/sqr(x*x+y*y+1.0) '1/(distance to centre of cube)
'unity radius adjustment
x1=x*w1
x2=x*w2
y2=y*w2
y-=sc
y1=y*w1
z1=w1
z2=w2
glTexCoord2f u1,v2 : glNormal3f x2,y2,z2 : glVertex3f x2,y2,z2'*1.2
glTexCoord2f u1,v1 : glNormal3f x1,y1,z1 : glVertex3f x1,y1,z1'*1.2
x+=sc
if u1+su<0 or u1+su>1.0 then su=-su
u1+=su
next
glEnd
y+=sc
v1=v2
next
end sub
X
