Shader tests

[fused]

That was cool 1.1.9?

yes

[fused]

im not bored yet

more displacement:

Code: Select all

    <material>
        <name>shader</name>
        <diffuse>
            <albedo>
                <shader>
                    <shader>
                        <![CDATA[   
 
                        def colorCalc(real x) vec3 :
                            vec3(
                                # compute color mix
 
                                #  color1 \/                      color2 \/
                                add(mul(0.75,x),mul(sub(1.0,x),0.00)),
                                add(mul(0.52,x),mul(sub(1.0,x),0.21)),
                                add(mul(0.00,x),mul(sub(1.0,x),0.88))
                            )
 
                        def eval(vec3 pos) vec3 :
                            colorCalc(
                                div(add(sin(mul(div(mod(doti(getTexCoords(0)),0.333333),0.333333),6.2831852)),
                                    sin(mul(div(mod(dotj(getTexCoords(0)),0.333333),0.333333),6.2831852))),2.0)
                            )
                        ]]>
                    </shader>
                </shader>
            </albedo>
            <displacement>
                <shader>
                    <shader>
                        <![CDATA[   
 
                        # sinus waves displacment U
 
                        def eval() real :
                            add(
			        mul(sin(mul(div(mod(doti(getTexCoords(0)),0.333333),0.333333),6.2831852)),7.5),
			        mul(sin(mul(div(mod(dotj(getTexCoords(0)),0.333333),0.333333),6.2831852)),7.5)
                            )
                        ]]>
                    </shader>
                </shader>
            </displacement>
        </diffuse>
    </material>

[Kosmokrator]

thats niiice!!!!

[CTZn]

im not bored yet

Nor are we

[fused]

heres a the checkerboard shader ive been planing to do for a long time.

with the shder lang updates in 1.1.10 its finally possible.

Code: Select all

<albedo>
   <shader>
      <shader>
         <![CDATA[   
               
         # checkerboard
                  
         def eval(vec3 pos) vec3 :
            vec3(
               if(
                  eq(
                     add(                                                 #\/ this controls the tiles
                        if(gt(mod(mul(doti(getTexCoords(0)),2.0),2.0),1.0),1,0),
                        if(gt(mod(mul(dotj(getTexCoords(0)),2.0),2.0),1.0),1,0)
                     ),1
                  ),0.85,0.025 # these values control the color
               )
            )
         ]]>
      </shader>
   </shader>
</albedo>

[pixie]

Awesome!

[Kram1032]

nice stuff

[CTZn]

Thanks fused, it's good to see advanced Indigo features being used !

I was wondering if there was existing an alternate way for scripting this checker effect, just another way to lay the code out ? Or does this language, as "functional", have only one way to be written (concatenating operations) ?

Subsidiary question: could one translate this checker code in another (readable) language, eventually pseudocode, so we can learn by comparison ?

Thanks, none of the above is mandatory.

[fused]

Thanks fused, it's good to see advanced Indigo features being used !

I was wondering if there was existing an alternate way for scripting this checker effect, just another way to lay the code out ? Or does this language, as "functional", have only one way to be written (concatenating operations) ?

im sure there are easier ways, ono said something about doing it with xor and floor, but this isnt in the shader language yet.
he also said what i did is a bit like xor.

Subsidiary question: could one translate this checker code in another (readable) language, eventually pseudocode, so we can learn by comparison ?

Thanks, none of the above is mandatory.

i think i can translate it to some pseudo code for you

Code: Select all

function eval returns vec3
{
   integer x

   integer color_u, color_v

   float tiles = 2.0

   if modulo(texture_coordinate_u * tiles, 2.0) > 1.0 color_u = 1
   else color_u = 0

   if modulo(texture_coordinate_v * tiles, 2.0) > 1.0 color_v = 1
   else color_v = 0

   x = color_u + color_v

   if x equal 1 return Vec3(0.0) //black_color
   else return Vec3(1.0) //white_color
}

i attatched an image that hopefully makes it a bit clearer for you.
as you can see black fields always have the values 0 or 2 and only white fileds can have the value 1.

and im sure there are better ways to do it or to explain it

[Kram1032]

Code: Select all

z = sgn( sin(x)+sin(y) )
if z == -1 col = col 1
if z ==  1 col = col 2
if z ==  NAN or 0 (depending on how sgn is defined...) col = (col1 + col2)/2)

sgn is the signum function.... sgn(x) = x/|x| and if specially defined, sgn(0) = 0

In case of higher dimensions (or complex numbers or such),

Code: Select all

sgn(x+y+....+?) = sqrt(x²+y²+...+?²)(x+y+...+?)/(x*y*...*?)

and represents an n-sphere...

http://en.wikipedia.org/wiki/Sign_function

I've no idea how fast that'd be, though....

to control the tile-width, you can modify the formula...

sin(x) has a wavelength of 2pi
to get a wavelength of 1, you need to use sin(2pi*x)
To get a wavelenght w, you need to use sin(2pi*x/w)

so the total formula is:

Code: Select all

z=sgn( sin(2pi*x/w_1) + sin(2pi*y/w_2) )
if z = -1 then col = col_1
if z =  1 then col = col_2
if z = NAN or 0 then col = (col_1 + col_2) /2

Code: Select all

x, y and z are real variables
w_1 and w_2 are constants
pi == pi                  ( d'oh )

[CTZn]

Woaow fused, that's a bit more than I expected, thanks a lot ! Now I understand the logic, I am able to run through (hopefully). The picture helps a lot

Kram: I don't understand your formula yet, but I bet fused way is faster since it involves less calculations but compares more (faster). A friend of mine called when I was reading your post, and he told me that signum was not reliable since it can't manage x = 0 (wich should not happen when dealing with a checker, but with computers you never know), he proposed:

Code: Select all

if x < 0
    return -1

if x > 0
    return 1

else return 0

Thanks !

[cpfresh]

this is all chinese to me, but is there a way to control the size of the checker grid? i appreciate the attempts at a 'dumbed down' explaination of the code in more code terms, but how about a plain english explaination? :/ eeerrgh

[PureSpider]

Code: Select all

<albedo>
   <shader>
      <shader>
         <![CDATA[   
               
         # checkerboard
                  
         def eval(vec3 pos) vec3 :
            vec3(
               if(
                  eq(
                     add(                                                 #\/ this controls the tiles
                        if(gt(mod(mul(doti(getTexCoords(0)),2.0),2.0),1.0),1,0),
                        if(gt(mod(mul(dotj(getTexCoords(0)),2.0),2.0),1.0),1,0)
                     ),1
                  ),0.85,0.025 # these values control the color
               )
            )
         ]]>
      </shader>
   </shader>
</albedo>

watch out for the "this controls the tiles"

[fused]

@cpfresh: purespider is right but maybe text size is playing tricks on you, so i added a better formatted version for you.

basically i calculate the color in u and v direction by multiplying the u/v value with the value for tilesu/tilesv. then i do a modulo of the value and 2 to get it in the range of 0-1.9999999. >1 is 1 and <1 is 0. at the end i add the resulting values for u and v together and if this value is 1 the texture at this position is white, else its black (have a look at the picture).

again, this is no perfect solution. i had this idea at work (so i was half absent minded ). ono posted a better way to do it on irc today. but it will only work in future versions (due to floor).

@CTZn: np

@Kram: nice solution, pretty clever (cleverer than mine )

Code: Select all

<albedo>
   <shader>
      <shader>
         <![CDATA[   
               
         # checkerboard
                  
         def eval(vec3 pos) vec3 :
            vec3(
               if(
                  eq(
                     add(
                        if(gt(mod(mul(
                           doti(
                              getTexCoords(0)),
                              2.0   # this value controls the tiles in u direction
                           ),2.0),1.0),1,0),

                        if(gt(mod(mul(
                           dotj(
                              getTexCoords(0)),
                              2.0   # this value controls the tiles in v direction
                           ),2.0),1.0),1,0)
                     ),1
                  ),0.85,0.025 # these values control the color
               )
            )
         ]]>
      </shader>
   </shader>
</albedo>

[Whaat]

Your tests are great, fused! Thanks!