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Copy path3d_sphere_mapped_and_shaded.lua
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3d_sphere_mapped_and_shaded.lua
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-- 3d sphere mapped and shaded v.1
-- explore option of an angle gradient in the x-axis (around the y-axis)
-- explore rendering 3 spheres with offset rotations (120 degrees)
-- succeeded in this version, extract hue to obtain an angle gradient
-- produces rgb gradient mapped to a 3d sphere with y-axis in the alpha channel
function prepare()
-- tilt & rotation precalc
radius = get_slider_input(RADIUS)
angle = get_angle_input(ROTATION)
angle_r = math.rad(angle)
angle_g = math.rad(angle + 240)
angle_b = math.rad(angle + 120)
cosa_r = math.cos(angle_r)
sina_r = math.sin(angle_r)
cosa_g = math.cos(angle_g)
sina_g = math.sin(angle_g)
cosa_b = math.cos(angle_b)
sina_b = math.sin(angle_b)
tilt = math.rad(get_angle_input(TILT))
cosa_t = math.cos(tilt)
sina_t = math.sin(tilt)
phase = math.rad(get_angle_input(PHASE))
cosa_p = math.cos(phase)
sina_p = math.sin(phase)
angle_e = math.rad(get_angle_input(ELEVATION))
cosa_e = math.cos(angle_e)
sina_e = math.sin(angle_e)
-- intended for screen relative rotation; produced tilt instead
-- ox,oy = 0.5, 0.5
-- roll = math.rad(get_angle_input(ROLL)-180)
-- sina_t,cosa_t = math.sin(roll), math.cos(roll)
-- add lighting
shaded = get_checkbox_input(SHADED)
end;
function get_sample(x, y)
-- image generation
local px = (x*2.0) - 1.0
local py = (y*2.0) - 1.0
local px_p = (x*2.0) - 1.0
local py_e = (y*2.0) - 1.0
px = px/radius
py = py/radius
px_p = px_p/radius
py_e = py_e/radius
local len = math.sqrt((px*px)+(py*py))
if len > 1.0 then return 0,0,0,0 end
-- local ox,oy = px,py
local z = -math.sqrt(1.0 - ((px*px)+(py*py)))
local pz = -math.sqrt(1.0 - ((px_p*px_p)+(py_e*py_e)))
local tz = (cosa_t * z) - (sina_t * py)
local ty = (sina_t * z) + (cosa_t * py)
z = tz
py = ty
local tx_r = (cosa_r * px) - (sina_r * z)
local tz_r = (sina_r * px) + (cosa_r * z)
px_r = tx_r
z_r = tz_r
local tx_g = (cosa_g * px) - (sina_g * z)
local tz_g = (sina_g * px) + (cosa_g * z)
px_g = tx_g
z_g = tz_g
local tx_b = (cosa_b * px) - (sina_b * z)
local tz_b = (sina_b * px) + (cosa_b * z)
px_b = tx_b
z_b = tz_b
local tpz = (cosa_e * pz) - (sina_e * py_e)
local tpy_e = (sina_e * pz) + (cosa_e * py_e)
pz = tpz
py_e = tpy_e
local tpz = (cosa_p * px_p) - (sina_p * pz)
local tpx_p = (sina_p * px_p) + (cosa_p * pz)
px_p = tpx_p
pz = tpz
-- intended for screen relative rotation; produced tilt instead
-- local nx = cosa_t * (x-ox) - sina_t * (y-oy) + ox
-- local ny = sina_t * (x-ox) + cosa_t * (y-oy) + oy
-- original line; not applicable here but defines what gets rotated
-- local r,g,b,a = get_sample_map(nx, ny, SOURCE)
h,s,l = fromrgb(px_r,px_g,px_b)
-- input image
local r, g, b, a = get_sample_map(h, py/2+.5, SOURCE)
-- input curve
px_p = get_sample_curve(x,y,px_p/2+.5,PROFILE)
-- return h,py/2+.5,px_p,1
if shaded then
return (r*px_p)+px_p, (g*px_p)+px_p, (b*px_p)+px_p, a
else
return r, g, b, a
end;
end;
function fromrgb(r, g, b)
local max, min = math.max(r, g, b), math.min(r, g, b)
local h, s, l
l = (max + min) / 2
if max == min then
h, s = 0, 0 -- achromatic
else
local d = max - min
local s
if l > 0.5 then s = d / (2 - max - min) else s = d / (max + min) end
if max == r then
h = (g - b) / d
if g < b then h = h + 6 end
elseif max == g then h = (b - r) / d + 2
elseif max == b then h = (r - g) / d + 4
end
h = h / 6
end
return h, s, l or 1
end