Conecting Arrays To Color Ramp

[bradon]

I am trying to connect the output from the colorAtPoint command into a color atribute of another shader. I don't know where to begin as far as formating this string so that it can be properly read. Is there a way to make a runtime command that links the RGB output of the "colorAtPoint" to the RGB input of a color ramp?

I am trying in the expression editor to run the command but I don't know what kind of array to use to store the output colorAtPoint and what kind of array to use to read it and input it into the ramp? also it seems as thout the colorAtPoint command is just used once and isn't really meant to be a node or something that has an output. the only place I can run it from is from the script editor, it doesn't seem to work in the expression editor?

sorry this is a big problem and I dont know where to begin.

[bradon]

well I esentially am close to the effect I was hoping for. this was the code in the expression editor that I used.

float $u = color_control.translateZ;
float $v = color_control.translateX;

float $pos[] = colorAtPoint -o RGB -u $u -v $v file\_for\_driver;

vectorProduct1.input1X = $pos[1];
vectorProduct1.input1Y = $pos[2];
vectorProduct1.input1Z = $pos[3];

I then linked the output of the Vector to the Color of the shader. It seems to work but has a few bugs. I cannot seem to get any values in the blue channel? and also the red and black areas seem to be reversed? I tried to take it all apart and make sure everything is working corectly and as far as I can tell everything should be fine. the order at which ColorAtPoint outputs values seems to be BRG? instead of RGB? but I cannot guess why this would be this way. Maybe there is something wrong with my texture file though? I am going to post the file so that maybe someone can take a look at if and see if there is some error I am neglecting.

here is the link.

www.paraportable.net/files/color\_node.zip

[bradon]

ah theres the problem!Arrays start at 0 not 1.
the code should be this:

float $u = color_control.translateZ;
float $v = color_control.translateX;

float $pos[] = colorAtPoint -o RGB -u $u -v $v file\_for\_driver;

vectorProduct1.input1X = $pos[0];
vectorProduct1.input1Y = $pos[1];
vectorProduct1.input1Z = $pos[2];

I also had to rotate the square 90 degrees to get the control coordinates to line up with the UV texture space correctly I am not sure why this did not default to the correct position? the link is still the same I repaired the file reposted it for anyone to take a look at it.

with this code I should be able to sample a range of points in the texture file
colorAtPoint -mu 0 -mv 0 -xu 1 -xv 1 -su 10 -sv 10
Can anyone tell me what vector/array/matrix/or node I might use to apply a range of color points to the color attribute of another shader? not like an average, but to somehow span or ramp those colors across the entire surface.

[joojaa]

Just out fo curiosity why would you use color at point at all? Since the uv cordinates stay the same, just connect the output fo the shader directly?

Se theres nothing that states a shading network cant have many shaders output in it! you can connect out color fof shader 1 to a reamps in uv... I do it all the time.

Or are you perhaps transfeering render data between 2 different objects? Even i that case i wouldnt start off with color at point. Then youd have 6 better options

1 ) Refenrece object that you use to read the data.
2 ) use pointOnSurfaceInfo/pointOnMeshInfo node instead.
3 ) bake with surface sampler.
4 ) bake with mr
5 ) bach conevrt use convert to solid isntead a s a preprocxessing instruction and read that file, rather than push and interpolate yourself.

And hardest (and by no means hard) but definetly the most flexible one

6 ) make a node that passes a nodal interface to teh api command MRenderUtil::sampleShadingNetwork

Se the reason why you cant ask for the array is that you dont know in advace what points would be sampled.

[joojaa]

PS i did chek your file but ists till not clear what you want to do!

but basicaly what your doing is sharing a file with testures... personlay i dont realy see any reason why youd want to use colorAtPoint in yoru example file at all.

Anyway i can see what one would want to do if it was a PURe trasfeerrral but atlest your demo file sint doing that.

Anyway explain a bit better what it is you wnat to do. And yes you can sue shading networks to dirve uvs no problemo.

[bradon]

Thanks for all the help (again).

yea the solution I worked up doesn't really do what I wanted it to. essentially I want to try and make a shader that acts like a cameleon. I don't want a direct relation from one shader to another shader (in that case I would just connect the output directly in the hypergraph. I want an interpretation of all the colors/shaders/objects below an object. it would be a bonus if lighting and rendering information were included. Say I have a sphere, and the sphere is on a red plane; then the sphere would be red, if the sphere was moved to sit onto a blue plane then the sphere would change to be blue. and if it was half and half, it would be half and half. It would be great if there was a way for the shader to be able to sample multiple objects and surfaces and textures at once. ColorAtPoint doesn't do this so maybe what you suggested will? I was thinking of parenting a camera to the cameleon object (that is orients straight down below the object) and connecting a sampling node to that so it only looks to pick up what is directly below the object and not to the sides. Also not just looking for a single frame solution so I don't know if baking would be the best route, could rebake at every frame? this is only a technical exercise for me so I am not looking for a specific effect, just the point of doing so. I am just guessing about these things since I really don't know the best way to go about doing this, colorAtPoint was a bad guess. I'll look through your options and see if I can't come up with anything better.

best,
Bradon

[joojaa]

Still no need for this. you can just feed the uv values to the texture in question!

So no need to use color at point! A bit of cmplexity here depens on wether or not you want to use heres a example of a scene thet does this: (ive posted thsi before si only needed the plane tp show what it references to, note each sphere only saples one point, nothin realy states they couldnt sample more!)

oh yeah and the scene:

CODE
file -f -new;
source AEswitchControlTemplate;

//lets create a array of chameleons
sphere -p 0 0 0 -ax 0 1 0 -ssw 0 -esw 360 -r 3 -d 3 -ut 0 -tol 0.01 -s 4 -nsp 2 -ch 0;
for($i=0;$i<10;$i++){
for($j=0;$j<10;$j++){
  duplicate;
  move -a (6*$i) 0 (6*$j);
}
}
shadingNode -asTexture ramp;
connectAttr -force ramp1.outColor lambert1.color;
shadingNode -asUtility multiplyDivide;
connectAttr -f multiplyDivide1.outputX ramp1.vCoord;
setAttr multiplyDivide1.operation 2;
shadingNode -asUtility singleShadingSwitch;

connectAttr -f singleShadingSwitch1.output multiplyDivide1.input1X;
AEswitchAddButtonCB singleShadingSwitch1 input inShape inSingle;
$i=0;
for ($item in ls -g){
$parent=listRelatives -parent $item;
connectAttr -f ($parent[0]+".translateX") singleShadingSwitch1.input[$i].inSingle;
$i++;}
setAttr "multiplyDivide1.input2X" 60;

//lets create the plane

nurbsPlane -p 28.5 -2 28.5 -ax 0 1 0 -w 57 -lr 1 -d 3 -u 1 -v 1 -ch 1;
// oops my us and vs vere read wrong
// no biggie
reverseSurface -d 3 -ch 1 -rpo 1 "nurbsPlane1";
shadingNode -asUtility place2dTexture;
shadingNode -asUtility multiplyDivide;
connectAttr -f place2dTexture1.vCoord multiplyDivide2.input2X;
connectAttr -f multiplyDivide2.outputX singleShadingSwitch1.default;
setAttr "multiplyDivide2.input1X" 60;

here they only ose one crd dimension but they could use 2 too just change the switch to double switch.... you get the picture

PS clear away a bit of the "chameleons" and move a sphere and notice how the sphere allways reflects teh color.

But yeah with raytracing you could make enev a full ccmalmeleon that reacts to all environ.