jornadas sobre estrategias de generación de entornos...

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ModellingModelling natural natural scenes: a forestscenes: a forest

Gustavo Gustavo PatowPatowGeometryGeometry andand Graphics Group (GGG) Graphics Group (GGG)

UniversitatUniversitat de Girona (de Girona (UdGUdG))

Jornadas sobre estrategias de generación de entornos colaborativos virtuales

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Create a GRID opCreate a GRID op

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Position the GRIDPosition the GRID

ManuallyManually

At origin by At origin by pressing pressing ENTERENTER

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Create a BOXCreate a BOX

You can You can create it at create it at the origin the origin withwith

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Resize the BOXResize the BOX

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Resize the BOXResize the BOX

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Nodes weNodes we’’ve createdve created

A Grid and a BoxA Grid and a Box Now, get sure you have the Box selectedNow, get sure you have the Box selected……

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Create a COPY opCreate a COPY op

From the Modify menu, select COPYFrom the Modify menu, select COPY

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Select the gridSelect the grid……


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…… and press ENTERand press ENTER


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Now we have a Box for every point on the Now we have a Box for every point on the Grid!Grid!


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Resulting NetworkResulting Network

This is the resulting networkThis is the resulting network–– All objects we had are now a All objects we had are now a singlesingle object object –– the single object has all the nodes for the the single object has all the nodes for the

operations so faroperations so far

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We can modify any node in the history of We can modify any node in the history of the current objectthe current object–– E.g. use middle button to reE.g. use middle button to re--adjust box sizeadjust box size


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We can modify any node in the history of We can modify any node in the history of the current objectthe current object–– Or the grid total sizeOr the grid total size……


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We can modify any node in the history of We can modify any node in the history of the current objectthe current object–– …… or its number of divisions!or its number of divisions!


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Change layoutChange layout

We want somethingWe want something–– More organicMore organic–– Not so regular!Not so regular!–– We can operate on the grid directly, not on We can operate on the grid directly, not on

the result!the result!

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Add a Scatter nodeAdd a Scatter node

Click on the shelfClick on the shelf

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Scatter has created 5000 points!Scatter has created 5000 points!


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LetLet’’s change it to 200 points!s change it to 200 points!


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Select the node and Select the node and ““view pointsview points”” to see to see what Scatter does!what Scatter does!


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Mountain nodeMountain node

Select the Grid nodeSelect the Grid node And create a And create a ““MountainMountain”” nodenode

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This deforms the surface along the Y axisThis deforms the surface along the Y axis


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We can increase randomness in YWe can increase randomness in Y……


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And still play with all the other values as And still play with all the other values as before!before!


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Select the Mountain nodeSelect the Mountain node And press TabAnd press Tab To access some more functionalityTo access some more functionality


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In particular, we want to add an attribute In particular, we want to add an attribute the the thethe pointspoints……

For that, letFor that, let’’s create an s create an AttribCreateAttribCreate nodenode

AttribCreateAttribCreate nodenode

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LetLet’’s create a new attributes create a new attribute And call it And call it pscalepscale..


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This is a global parameter that is helping This is a global parameter that is helping the the CopyCopy nodenode……


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The copy node uses The copy node uses pscalepscale to control to control particle sizesparticle sizes


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Click on the output of the Click on the output of the AttribCreateAttribCreate And select/type PaintAnd select/type Paint……

Paint nodePaint node

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It allows us to It allows us to paintpaint attributes in a more attributes in a more ““organicorganic”” way!way!


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Select Select ““Override ColorOverride Color”” And select And select pscalepscale


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And change And change ““radiusradius”” to 1to 1


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Change value of Foreground Color (FC) to Change value of Foreground Color (FC) to 5 5 55 5 5


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Change Change ““OpacityOpacity”” to 0.01to 0.01


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Now, we can Now, we can ““paintpaint”” our attribute with our our attribute with our left mouse button!left mouse button!


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If we increase our FC to 10 If we increase our FC to 10 1010 1010 changes changes will be faster (but the affected area will be will be faster (but the affected area will be the same)the same)


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If you play with the number of particles in If you play with the number of particles in the Scatter node, distribution of big/small the Scatter node, distribution of big/small will remain correct!will remain correct!


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All cubes are equally oriented (axis)All cubes are equally oriented (axis) LetLet’’s use an expression to break this!s use an expression to break this! Right click on the Box outputRight click on the Box output

Transform nodeTransform node

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Transform nodeTransform node

And create a Transform node!And create a Transform node! It permits rotation along YIt permits rotation along Y

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And write there the expressionAnd write there the expression

stamp(stamp(““../copy1../copy1””, , rotateshaperotateshape, 0), 0)

Transform node Transform node -- StampStamp

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stamp(stamp(““../copy1../copy1””, , rotateshaperotateshape, 0), 0)

Here:Here:–– Stamp is the expression commandStamp is the expression command–– ““../copy1../copy1”” is the location of the copy nodeis the location of the copy node–– RotateshapeRotateshape is a variable we createis a variable we create–– 0 is the default value if that variable is not 0 is the default value if that variable is not

foundfound

Transform node Transform node -- StampStamp

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Copy Copy -- StampStamp

Back at the Copy node, letBack at the Copy node, let’’s select s select ““StampStamp”” to create the variableto create the variable

And turn on And turn on ““Stamp InputsStamp Inputs””

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And create And create ““rotateshaperotateshape”” If you give a constant value (e.g. 10), all If you give a constant value (e.g. 10), all

points will be affected by the same points will be affected by the same rotationrotation


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So, letSo, let’’s uses userand($PTrand($PT)*360)*360

To get random values between 0To get random values between 0 and 360and 360$PT is the unique point identifier$PT is the unique point identifier……


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And we get a random distribution of And we get a random distribution of rotated boxes!!rotated boxes!!


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LL--System nodeSystem node

Now, letNow, let’’s create something more exciting!s create something more exciting! Thus, deselect any node, press TabThus, deselect any node, press Tab……

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And create an LAnd create an L--System nodeSystem node It is almost like a little treeIt is almost like a little tree

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And feed it into the transform node!And feed it into the transform node!

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Creating a Creating a ““LoDLoD”” systemsystem

At the output of the LAt the output of the L--SystemSystem Create a Switch nodeCreate a Switch node And wire the box node too!And wire the box node too!

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““LoDLoD””

We can switch:We can switch:–– 0 for trees0 for trees–– 1 for boxes1 for boxes

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We can switch the orderWe can switch the order And weAnd we’’ll have ll have

–– 0 for the boxes0 for the boxes–– 1 for the L1 for the L--System System


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We can change the boxes to be of sizeWe can change the boxes to be of size0.3 1 0.30.3 1 0.3

so they look like a lowso they look like a low--res version of the res version of the treestrees


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HDAHDA

Houdini Digital AssetHoudini Digital Asset Allows easy sharing of systemsAllows easy sharing of systems Encapsulates behavior into higherEncapsulates behavior into higher--level level

unitsunits Behaves as any other Houdini nodeBehaves as any other Houdini node

–– Seamlessly increases available tools!Seamlessly increases available tools!

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Select all of our nodesSelect all of our nodes

And pressAnd press

To create a collapsed subnet nodeTo create a collapsed subnet node

HDA Creation: SubnetHDA Creation: Subnet

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HDA CreationHDA Creation

LetLet’’s rename it to s rename it to ““forestforest””

Right click and select Right click and select ““Create Digital Create Digital AssetAsset””

Change to “forest”

PressAccept

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HDAHDA

Creation GUICreation GUI

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User interface designUser interface design

We can choose a variety of parametersWe can choose a variety of parameters

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We can create new attributes ourselvesWe can create new attributes ourselves……


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We can take them directly from our We can take them directly from our nodes!nodes!


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We do not want to change the parameter We do not want to change the parameter namesnames……


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Just drag the parameter to the interface!Just drag the parameter to the interface! LetLet’’s select the s select the ““Select InputSelect Input”” of the Switchof the Switch


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We have added one parameter!!!We have added one parameter!!!


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The The ““SizeSize”” of the Grid nodeof the Grid node……


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The The ““heightheight”” of the Mountainof the Mountain


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The number of points from the ScatterThe number of points from the Scatter


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If you want, you can change any label!If you want, you can change any label! E.g. E.g. ““Number Of TreesNumber Of Trees””


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Accept, and click one level upAccept, and click one level up……


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We can further editWe can further edit To add a default value to 0 to our To add a default value to 0 to our LoDLoD

selectorselector


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Select Select ““MenuMenu”” tabtab Activate Activate ““Use MenuUse Menu”” AddAdd

–– 0 Boxes0 Boxes–– 1 Trees1 Trees

Delete this line!


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We have a new menu item to select We have a new menu item to select between boxes and trees!between boxes and trees!


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HDA in action!HDA in action!

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SummarySummary

Created a simple Grid and a cubeCreated a simple Grid and a cube Build a fairly complex systemBuild a fairly complex system Encapsulated into a new digital assetEncapsulated into a new digital asset

–– We can share this new node typeWe can share this new node type–– Being able to create a whole forest with Being able to create a whole forest with oneone

node!node!

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