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Burger On The Grill

Part 16: Pouring a Drink--Condensation

After completing the donut tutorial by BlenderGuru, I was challenged to create something similar by myself, so I made a burger. I will make that burger into a meal with a soda and fries.

In the last parts, I showed how to make carbonation foam and fizzy bubbles. Now, I'll reveal how to add condensation to the outside of the glass.

Adding Droplets

In a previous part, I showed how to add dewdrops to tomato slices by creating metaball instances with geometry nodes, a method that is shown in this tutorial by Weil Labed. This method was problematic from the start, requiring multiple workarounds.

In Blender 3.3, metaball instances may show up in the render preview window but disappear in the actual render. Using Eevee, you can go to View and select Viewport Render Image; however, the resolution may be less than what you'd get from an actual render. Since we are using Cycles as the render engine, I had to move on from metaballs.

Joey Carlino offers an alternative method of generating water droplets with geometry nodes by converting Points to Volume and Volume to Mesh.

Water Droplets with Geometry Nodes by Joey Carlino

Start by creating a duplicate of the soda glass. Add a geometry nodes modifier with these nodes and values.

In weight paint mode, paint the entire glass blue and then paint warm colors where you want your droplets. Under Object Properties > Vertex Groups, name this weight paint “Big Drops.”

Repeat the process a second time, adding smaller droplets. Increasing the voxel amount will yield better resolution on a smaller scale. Create another weight paint vertex group named “Small Drops.”

I used the same node setup but with these values:

• Drop Density Multiplier: 6000

• Distribute Points of Faces > Distance Min: 0.002m; Seed: 9

• Random Value > Min: 0.13; Max: 0.35

• Volume to Mesh > Voxel Amount: 1000

There are now water droplets on the glass, but at a glance, they can be easily mistaken for carbonation bubbles. How can we get a more integrated effect?

Painting Drip Trails

Blender Guru combines image textures with a particle system that instances a collection of droplets.

How to Make a Rainy Window by Blender Guru

I liked how some of these droplets had trails behind them. This is a good method if you have the water rolling down a flat surface; however, with a complex curving surface, like we have on our glass, the trails would stick out unnaturally as instances.

Jonathan Kron demonstrates a method that solves this problem, using instanced particles in combination with dynamic paint to create trails in the roughness of the texture of the container.

Realistic Condensation by Jonathan Kron

It turns out that dynamic paint works just as well with geometry nodes as it does with the particle system.

Let's make some drip trails for the big droplets!

With the Big Droplets selected, go to Physics Properties and add Dynamic Paint with these settings:

• Type: Brush

• Paint: Mesh Volume + Proximity

• Distance: 0.001

With the Glass selected, add Dynamic Paint with these settings:

• Type: Canvas

• Format: Vertex

• Frame End: 19

• Drip: Checked

• Weights > Gravity: -1

• Output > Wetmap Layer: Click + sign

If you run the animation now, you’ll notice the trails being painted up are a bit messy and out of sync with the droplets. To fix this, add a Subdivision Surface Modifier to the glass set at 2 and drag it above the Dynamic Paint in the modifier stack.

On the Dynamic Paint canvas, under Cache, click Bake. This will produce an attribute called “dp_wetmap” which can be dragged into the Shader Editor of the Glass to drive the texture.

Adding subdivisions to the glass helps to get a cleaner wetmap, but at the cost of nearly maxing out my graphics card. To prevent failed renders, it is necessary to reduce the load.

Our wetmap is operating as vertex color, which is intrinsically tied to the vertices of the highly-subdivided mesh. In this form, the wetmap cannot be transferred to a lower poly mesh. How can we get around this problem?

The answer is baking. We can bake this wetmap to an image texture which can be used on a simpler mesh.

Converting vertex painting to texture maps by Taylor Hokanson

Connect the color sockets between the wetmap attribute and a diffuse shader. Add an image texture node and create a new 4K image with a black background and no alpha channel. Add a UV map node and connect it to the vector input of the image texture node.

Create a new UV map named "Drip" to be referenced by this UV map node. Since we already have a UV map for the Coca Cola logo, we will be working with multiple UV maps.

Texturing with Multiple UV Maps by The Observatory

Go to Object Data Properties > UV Maps and click the + sign to create a new UV map. Open the new black image in the UV Editor, mark seams in discreet areas, unwrap the UVs and position and size the islands to maximize the area taken up by the drip trails.

Go back to the Shader Editor and select the name of the new UV map in the UV map node. Make sure the image texture node is selected. Then, go to Render Properties > Bake. Set the Bake Type of Diffuse and make sure only the Color Contribution is checked under Influence. Bake and save your image to the hard drive as "DripTexture."

Now, we need to transfer the "Drip" UV map from the high-poly subdivided glass ("source" object) to the low-poly unsubdivided glass ("target" object).

Go to Object Data Properties > UV Maps on the source object and make sure the UV Map for the drip texture is active. For the target object, click the + sign to add a new UV map and make sure it is active. Select the target object and then the source object. Go to Object > Link/Transfer Data > Copy UV Maps. The new UV map of the unsubdivided glass object will be replaced by a copy of the drip texture UV map from subdivided glass object.

Set up the following nodes for the low-poly unsubdivided glass.

Feed a UV Map node referencing "Drip" into the Vector socket of an Image Texture node referencing "DripTexture." Invert the color and add a Color Ramp to decrease the maximum brightness.

Using vertex paint, paint the entire glass black. Paint white on the outside of the glass below the level of the liquid, creating a soft transition at the level line. Add a Color Attribute node and reference the vertex paint which needs to be named "Col" to avoid render problems.

Feed the Color sockets of the ColorRamp and Color Attribute nodes into a Math node set to Multiply. Feed the result into the Roughness socket of the Tricky Glass Shader.

This effect looks good on a metal can, but increasing the roughness on a glass material makes it difficult to see the details on inside the glass, the ice cubes and carbonation bubbles we worked so hard on.

Adding an Image Texture

To add more spaces where the roughness is lower and further integrate the droplets to the glass, I decided to add another image texture.

Blender Guru uses multiple materials and adds a condensation texture to his coffee glass.

Condensation by Blender Guru

Create a new UV map for the Glass and name it “Condensation.” In the UV Editor, bring up the Condensation Image Texture in the background.

Mark seams around the base and the fill level of the glass. Choose a discreet place to mark a seam down the side of the glass. Select the glass and UV > Unwrap. You might notice that the result is somewhat curved, causing the texture to stretch along the glass.

To fix this, we need to use a different unwrapping method.

Add a camera and change the lens type to Orthographic. Name the camera “UV Cylinder Projection.” With the camera selected, go to View > Cameras > Set Active Object as Camera. Position the camera to face the vertical seam through the glass as shown in the image below.

Drag the UV islands outside of the Condensation Image Texture. Then, select only the island where you want the texture to appear on the outside of the glass.

Go to UV > Cylinder Projection. Set the Direction to View of Equator. That island should now fill the whole square of the image texture, maximizing resolution without stretching the texture.

In the Shader Editor, drag in the Alpha Masked and Normal textures for the Condensation. Feed a UV Map node into the Vector input and use a Mapping node to scale them. The Normal texture will drive the Displacement while the Alpha Masked texture will contribute to the Roughness of the Glass Shader. Use a Vertex Color to control where the condensation appears on the glass.

Reference Condensation Texture Shader Nodes at the top of this post.

The Foggy Texture creates some randomness in the application of the condensation and the Bottom Gradient decreases the amount of condensation as you move down the glass and away from the ice.

Combining Effects

Pulling it all together requires an even more complicated node tree, but essentially all that is left is to add the Wetmap Drip Texture frames and feed it into what we already have.

Reference Condensation + Drip Trails Shader Nodes at the top of this post.

Organizing node trees into frames is a good way to communicate your process to your future self and to others. Whole segments can easily be copied from one material to another.

Finally, we have completed our soda!

Follow me to keep watch for the next part! Now that we have our burger and our soda, we can start to set up our burger meal scene.

Review the previous part.

See overview for links to all parts of this tutorial series!

See more of my work: Check out my archive.

Join me on my journey: Follow me on tumblr.

Blender Basics Tutorial

This is the second of two new videos on my channel focused on Blender specifically for sims cc artists! This is great for both recolor artists and creators. I go super slow and explain everything I am doing in lots of detail. I have files for you so you can work alongside me in these videos! All the download links are in the youtube description :)

This one is long so grab a glass of wine while you watch! I made sure to not make any assumptions and skip around. I took my time to show you all the steps and different ways of doing things. 

This tutorial covers: 

Modifying meshes 

Editing UV maps 

Assigning materials 

Essential tips and tricks 

Cosmic Heart Compact Blender Speed modeling

Burger On The Grill

Part 15: Pouring a Drink--Adding Fizz

After completing the donut tutorial by BlenderGuru, I was challenged to create something similar by myself, so I made a burger. I will make that burger into a meal with a soda and fries.

In the last part, I showed how to make superior photorealistic carbonation foam. Now, I will reveal how to add the rest of the fizzy bubbles.

A good glass of soda has more than foam. Bubbles cling to the bottom and sides of the glass, rise up through the liquid and spring out into the air.

Beer Tutorial: Adding Bubbles by BlenderGuru

Create a Bubble

Add an icosphere with a radius of 0.001m and a subdivision level of 1. This will be the object referenced by our particle systems.

Add the same material to this icosphere as you did to your foam spheres in the last part. Remember, we mixed Glossy and Transparent shaders. You can adjust the mix shader to make the bubbles more or less visible within the fluid.

Clinging Bubbles

To simulate bubbles clinging to the sides and base of the glass, we will add some particle systems with the particle type as hair. Let’s start with the base bubbles.

First, to create the root object from the which the hair will sprout, select the bottom of the liquid object, duplicate it, and separate it into a new object. Apply any modifiers. Reduce the geometry by dissolving edges and try to more-evenly distribute the faces. Scale down this object slightly so that it fits within the liquid object and move it to rest just above the bottom of the liquid.

Add a particle system to the object with these settings:

• Emission > Number: 200

• Source > Emit From: Faces, Uncheck Even Distribution

• Render > Render As: Object, Scale: 0.23, Scale Randomness: 0.8, Uncheck Show Emitter

• Object > Instance Object: Icosphere Bubble

• Viewport Display > Uncheck Show Emitter

Convert the particles system into an object mesh:

Select the Icosphere Bubble that we instanced, go to Object Data Properties, and click the number next to the name of the mesh at the top of the panel to separate it from any linked duplicates.

Select the object with the particle system and move it into a new collection by itself. Under Modifier Properties, under the Particle System, click Make Instances Real.

At the end of the collection, find and select the original object with the particle system. Delete it or move it outside of the collection and disable it for render.

Finally, select all objects in the collection and join them into a single object.

Repeat this process for the side bubbles.

First, create the root object by selecting the sides of the liquid, duplicating them, and separating them into a new object. Apply any modifiers. Reduce the geometry by dissolving edges, keeping in mind that the bubbles will be sprouting from the faces, and the more faces you have, the more bubbles. Scale down this object slightly so that it fits within the liquid object and the generated bubbles do not clip through the sides.

Add the particle system as before, adjusting the emission number to your liking. I set the number to 500 for the sides. Then, convert the particles system into an object mesh.

You could use this method again to simulate bubbles clinging to the ice cubes, giving the appearance that your soda has been resting for some time, but since I am going for an action shot, I want more bubbles traveling through the liquid and interacting with the ice cubes.

Rising Bubbles

To simulate the bubbles rising through the liquid, we will use another particle system and add an emitter.

First, to create the emitter object, select the bottom of the liquid object, duplicate and separate into a new object. Apply any modifiers. Scale down this object slightly so it fits within the liquid object and move it to rest just above your bottom bubbles. Reduce the geometry by dissolving edges and deleting random points until you have something that is not so uniform.

Add a particle system to the object with these settings:

• Particle Type: Emitter

• Emission > Number: 2000, Frame End: 30, Lifetime: 30

• Source > Emit From: Vertices

• Physics > Mass: 0.001 kg

• Forces > Brownian: 0.01

• Render > Render As: Object, Scale: 1.1, Scale Randomness: 0.8, Uncheck Show Emitter

• Object > Instance Object: Icosphere Bubble

• Viewport Display > Uncheck Show Emitter

• Field Weights > Gravity: 0

Now, we need to contain the flow and get it to interact properly with the ice cubes and the foam bubbles.

To contain the flow, select the liquid object and click on Collision under Physics Properties. This will cause the bubbles from the emitter to bounce around inside of the liquid object.

Next, select the foam bubbles object and add Collision to it as well. We want the bubbles to gather beneath this object instead of bounce off of it, so we need to set Damping and Friction to 1.

Finally, select the ice cubes object and add Collision to it also.

In the reference photos, the bubbles seem to cling and slide up along the ice cubes as they rise. Sometimes, bubbles even seem to be trapped within the ice.

Like with the foam bubbles object, we can get the bubbles to cling to the ice cubes by adjusting the stickiness and friction settings. I set Stickiness to 5 and Friction to 0.5. We can even allow some bubbles to travel through the ice cubes, giving the appearance of being trapped inside, by increasing the permeability setting. I set Permeability to 0.25.

Because this process can involve a lot of fine tuning and you will be working will a lot of particles, the Cache becomes a rather important tool. Add a name for your cache. I called mine “RisingBubbles.” Make sure that Disk Cache and Use Library Path are checked. These options save the particle motion to your disk instead of just your RAM so that if your program needs to be restarted for some reason, you will not lose your work and have to wait for the point cache to be recalculated.

Click Bake to calculate your point cache for multiple frames. This will give you a nice progress bar to look at while the program freezes up to do your calculations. Once you are finished baking, if you want to change any settings again, click Free Bake. This will allow you to make adjustments, but will require you to bake again.

Choose a frame where the emitter bubbles are to your liking. I chose frame 26. Select the Emitter object. On the menu bar, choose Object > Apply > Make Instances Real. This will create an object for each particle at the position calculated for the current frame. Group these new bubble objects into a collection and name them “Baked Rising Bubbles.” Select all objects in the collection and join them into one object.

Here is the inside of the liquid so far with all the different bubbles.

Flying Bubbles

To simulate the bubbles flying out from the top of the foam, we will create another emitter.

Select the top of the liquid object, duplicate and separate into a new object. Apply any modifiers. Move the object just above the top of the liquid and scale it down so that the generated bubbles do not touch the top of the liquid or the sides of the glass.

Add a particle system to the object with these settings:

• Particle Type: Emitter

• Emission > Number: 4800, Seed:1, Frame End: 10, Lifetime: 5

• Source > Emit From: Faces

• Physics > Mass: 0.001 kg

• Forces > Brownian: 0.02

• Render > Render As: Object, Scale: 0.6, Scale Randomness: 0.8, Uncheck Show Emitter

• Object > Instance Object: Icosphere Bubble

• Viewport Display > Uncheck Show Emitter

• Field Weights > Gravity: 1.5

To direct the flow, add Collision settings to the glass and the liquid objects and check Kill Particles. Make sure to turn off collision settings for all other objects in the scene.

Choose a frame where the emitter bubbles are to your liking. I chose frame 8. Select the Emitter object and Make Instances Real. Group the new bubble objects into a collection and name them “Baked Flying Bubbles.” Select all objects in the collection and join them into one object.

We have our carbonation!

Follow me to keep watch for the next part! We are almost done with the soda, but there is one last step. No iced beverage is complete without condensation.

Review the previous part.

See overview for links to all parts of this tutorial series!

See more of my work: Check out my archive.

Join me on my journey: Follow me on tumblr.

Burger On The Grill

Part 14: Pouring a Drink--Foam Physics

After completing the donut tutorial by BlenderGuru, I was challenged to create something similar by myself, so I made a burger. I will make that burger into a meal with a soda and fries.

In the last couple of parts, I showed you 3 fast ways of creating foam and how to add ice cubes.

Now, I have developed a method for making superior photorealistic carbonation foam, but no one has been reading these tutorials lately, so I won't bore you with the painstaking step-by-step process. That could be a course in itself and until someone expresses interest, I'll let it be my little secret.

What I can give you now is an overview of my method and a few tips.

Compare the fast foam results with any reference and you'll see that there are some limitations to how I have modeled the foam. First, in carbonation, the bubbles should kiss but not combine. Second, the bottom of the foam should be uneven as it dips below the top of the liquid.

This kind of effect can only be modeled with the use of rigid body physics.

Rigid Body Foam Technique by Mentalist

Step 1: Make a Container

Duplicate the surface of the liquid and separate into a new object. From this starting point, model a container in which to drop your bubbles.

Only use as much geometry as you need to hold the shape; extra geometry slows down rigid body calculations.

Apply a solidify modifier to add thickness. This thickness will help prevent objects from falling through the container during rigid body calculations.

Duplicate the ice cubes and position them through the liquid surface of the container.

Scale both objects up by 100. Rigid body calculations work faster on large objects.

Keep track of your object origins and transforms so that you can size the objects back down later.

Step 2: Make Lots of Icospheres

Model a small collection of low-poly icospheres with different sizes.

Add a subdivided circular plane near the bottom of your container. This will be your Sphere Emitter.

This Geometry Node setup distributes points on the faces of the plane and puts an instance of the targeted object (which should be one of your icospheres) on these points. The scale of the icosphere is randomized between a small range. Then, the instances are made into real geometry which can later be separated.

Duplicate the Sphere Emitter until there are enough copies to target each size of icosphere in your collection. Decrease Distance Min and increase Density Max as the targeted sphere gets smaller.

Place your Sphere Emitter objects into a collection. Duplicate as desired and position inside the Container near the bottom. For each, in Edit Mode, Select All and Separate By Loose Parts.

You should now have thousands of individual spheres in the collection.

Step 3: Delete Intersecting

If you placed the spheres near the bottom of the container, as I told you, they should be intersecting with the ice cubes. This can be a problem for your rigid body simulation.

Use Dynamic Paint to select all the spheres that intersect with the ice cubes.

Select All Objects Inside A Mesh by vklidu

You will need to join all your spheres into one object and set it as a Canvas. The ice cubes will be your Brush.

To select the red spheres, go to Object Data Properties > Vertex Group > Select. Because some of the spheres were selected only partially, you can select these spheres whole by hitting Ctrl L to Select Linked.

Delete vertices. The only spheres left should be the ones outside of the ice cubes. Select All and Separate By Loose Parts.

Step 4: Set Up Rigid Body

Select all of the spheres and Set Origin to Geometry.

Add Rigid Body to the Container and the Ice Cubes, making these passive objects. Make the spheres active objects. Set the Friction to 1 and the Sensitivity Margin to 0.00004m.

Under Scene Properties, under Rigid Body World, set Substeps Per Frame to 250 and Solver Iterations to 40. Under Cache, set Simulation End to 100 and Bake.

Apply Transformation.

There is a small problem where the tiny spheres around the rim appear to be floating in empty space. To fix this a second rigid body transformation is required.

Remove rigid body and add it back again to reset the cache.

Select only the problematic spheres around the rim and move them to a new collection. These spheres will be active objects while all other spheres will be passive like your container and ice cubes.

Reverse the direction of gravity and Bake to 5 frames.

Apply Transformation and remove rigid body.

Join all of the spheres together into a Bubbles object. Reorient and scale down the object to match your scene.

Step 5: Add Material to Spheres

To make your spheres into bubbles, mix Glossy and Transparent shaders.

Here are the results so far.

You can see the specular highlights of the many bubbles, but if you look back at the reference image, you'll notice that the foam looks too dark.

This is not a lighting issue or a color issue. In real foam, those empty spaces between bubbles are filled with really really tiny bubbles. This adds up to a ton of tiny bright highlights.

Modeling and simulating all of those microscopic bubbles is impractical if not impossible.

So, instead, we can create another object to occupy this empty space and fill it with a volume shader.

Step 6: Create Volume Between Bubbles

This is definitely the longest and hardest step so I made an animation to clarify things.

When performing boolean operations, clean up your target and modified objects before AND after. Merge by Distance. Fix Non-Manifold geometry. Finish off incomplete cutting operations by deleting undesired geometry.

Check Face Orientation to adjust normals. The cover should be blue and the bubbles should be red. This orientation is important so that Blender knows which areas should be filled with volume and which should be left empty.

For the Boolean Intersect operation, check Self Intersection and Hole Tolerant. Expect Blender to freeze up for good long while as it calculates.

Because you will need to fix areas of clipping after this operation is finished, you need to have the areas affected by the boolean operation selected.

Before the operation, enter Edit mode on the object that will be cut and deselect all. Enter Edit mode on the targeted cutting object and select all. Now, after the boolean is completed, these areas should be selected automatically in Edit mode and you can save them as a Vertex Group.

Once you have your cover filled with red bubbles and all cleaned up, move it slightly below the surface of the liquid object to eliminate clipping errors with that surface.

Step 7: Add Volume Shader

Add Volume Scatter and Volume Absorption shaders to fill your object with a specific color.

I added Voronoi textures to simulate even smaller holes and highlights within this volume, but that node setup was too complex to capture in a screenshot. The setup was similar to what I used for the High Level Detail Foam.

Well, that was the final step. Enjoy your foam!

Follow me to keep watch for the next part! We will be adding some carbonation to the body of our flat soda.

Review the previous part.

See overview for links to all parts of this tutorial series!

See more of my work: Check out my archive.

Join me on my journey: Follow me on tumblr.