In this tutorial, I will describe the node setup I used to create a starry sky with bluish clouds, entirely procedural, in Blender 4.1, using the Cycles rendering engine.
Video Transcript
Hello everyone! In this tutorial, I will describe the node setup I used to create a starry sky with bluish clouds, entirely procedural, in Blender 4.1, using the Cycles rendering engine.
Therefore, we will not use any images, but only Blender's Procedural Noise and Gradient Textures. This will allow us to significantly modify the final effect, as we can vary the parameters of these objects without compromising the final quality of the result.
The inspiration comes from the night sky in of one of my favorite video games, "The Secret of Monkey Island".
Specifically, it's the night sky visible on Mêlée Island. We need to create three components for the World Background, in this order: the starry background, the bluish clouds, and the horizon glow.
The rendering I showed you earlier was made by adding a bit of glow to the stars and other effects in post-production using Nodes Compositing. After describing the node setup for the World Background material, we will also take a look at the post-production.
In a new Blender project, switch to a Shader Layout, or open a similar editor, and select World in the Shader selector.
Add a 3D View window to the Layout, so you can observe the various effects in real time in Rendered mode.
At this point, the background of the virtual universe will be set to Blender's default file settings, which in my case is a pure white color with an intensity value of 1.
Before proceeding, a very important note: DO NOT view the Rendered preview of the 3D Viewport in Orthographic mode, as it will not yield correct results! Therefore, use a free view in perspective mode.
Let's start by creating the starry background, which means starting with a black background on which stars will be applied, represented by colored dots with random distribution, intensity, and sizes.
To create a procedural black and white starry background, simply add a Noise Texture to the node setup and significantly increase the Scale parameter value, for example to 200 or more.
Also, set the Detail parameter value to at least 5 to achieve a better result.
Then, connect the Factor output of the Noise node to a Brightness Contrast node, setting the Brightness value to a negative number, such as -0.7.
The stars thus obtained have two issues: they are not bright enough and they are in black and white.
To make not only the stars but the entire virtual universe brighter, which will ultimately serve as the basic light source for the scene, increase the Strength parameter value of the World Background node, for example to 3. Remember that we will add an additional glow to the stars in post-production using Nodes Compositing.
Regarding the color, we cannot use the Color output of the Noise node because the result would be overly colorful.
However, we know that we can multiply the gray and white dots from the Noise node's Factor output by a randomly colored texture, thus obtaining colored dots of varying sizes and intensities. For this, we can use another Noise Texture, this time taking its Color output, with the Scale factor set to 100, so that we get many white areas and some colored areas.
To make the colors of this texture more vivid, use a Brightness Contrast node again, but this time leave the Brightness value at 0 and set the Contrast value to 0.7 or higher, as desired.
To get the colored stars, multiply the outputs of the two Brightness Contrast nodes using a Color Mix node in Multiply mode with Factor set to 1.
To conclude this part of the setup, connect the output of the Multiply node to a Gamma node, which allows us to show more or fewer stars, making them more or less bright, without brightening the background, because Gamma correction does not act like a Brightness node.
We've completed the first effect of this tutorial! We can group the nodes up to Gamma into a new group, naming it STARS, before moving on to the next effect!
The clouds and the horizon glow are each created in two parts. The first part defines the Texture that generates the effect, while the second part defines the blending factor that adds the effect to the sky achieved so far.
Since the clouds need to be blended with the starry background and then the horizon glow applied, let's start by defining the clouds.
In theory, creating bluish clouds should be a simple task because it is enough to add another 3D Noise Texture to the node setup, this time with Scale set to 3 and Detail set to 5, then take the Factor output of this node and pass this information to a Color Ramp node to define the color of the clouds.
The Color Ramp node can be set to your liking, through experimentation. In my case, I set the first marker to black with a position of 0.36, then set the second marker to pure blue with a position of 0.93, and then changed the interpolation mode to Easing.
With these two nodes, we already get procedural bluish clouds, but there's a problem: these clouds are present all over the virtual universe! We need them to start from a certain height on the horizon, with the ability to set this height as desired. Therefore, I want to create a gradient mask in black and white, to multiply with these clouds, intending to hide the clouds in the areas corresponding to the black zones of the gradient texture.
To do this, add a Gradient Texture of type Linear to the setup, and a Vector Mapping node in Point mode with Rotation Y set to 90°.
To achieve the correct mapping of this gradient, connect the Vector input of the new Vector Mapping node to the Generated output of a Texture Coordinate input node.
To be able to raise or lower the gradient's transition line, add a Color Ramp node to the setup. In this case, you will need to adjust the black marker on the left of the default Color Ramp to shift the gradient's transition point.
The two Color Ramps thus obtained can now be multiplied using a Color Mix node, in Multiply blending mode, with a blending factor of 1.
Now, you can also group this node setup into a new group, naming it CLOUDS.
Let's move on to the second part of the bluish clouds effect, which is its mixing with the starry background.
To add this effect to the starry background, insert another Color Mix node into the setup, but this time leave it in Mix mode instead of changing it to Multiply mode as we have done so far.
Connect the output of the STARS group to the first Color input of the new Mix node.
Then, connect the output of the CLOUDS group to the second Color input of the new Mix node.
Now we have both clouds and stars, but obviously, the stars should not be visible where the clouds are denser! To solve this problem, connect the output of CLOUDS to the Factor input of the Color Mix node that mixes the stars and clouds.
The output of CLOUDS we are using is not yet suitable because it is colored, and its intensity is not correct. To fix these issues, insert an RGB TO BW node and a Gamma node in sequence between the output of CLOUDS and the Factor input of the Color Mix node. Then, set a very low value for Gamma, such as 0.01.
The third and final effect is a slight glow on the horizon to add to the final effect.
The node setup for this third group can be derived by duplicating the sequence of nodes Texture Coordinate, Mapping, Gradient Texture, and Color Ramp from CLOUDS, then modifying the parameters of these nodes.
In fact, since we will also need RGB TO BW and GAMMA nodes, we can duplicate the CLOUDS group along with the two external nodes.
Attention here, as there is a very important operation to perform! At this moment, the copied group is an instance of the original CLOUDS group, so any operation performed on this group will also modify the original group!
Before performing any operation, click the button with the number 2 inside the group to make it a separate group from the original. Blender will rename this new node to Clouds 001.
First, rename the new group to HORIZON-GLOW, then enter the group.
Delete the Noise Texture, Color Ramp, and Multiply nodes from HORIZON-GLOW, connecting the first Color Ramp directly to the group's output.
Change the mode of the Gradient Texture node from Linear to Easing, to achieve a smoother transition.
Now we have a gradient mask that is black at the horizon and gradually lighter towards the top.
Select the first marker of the Color Ramp, change it to a dark bluish-green color, such as RGB 0.007, 0.018, 0.031, keeping it at position 0.0.
Select the second marker, move it to position 0.09, very close to the first, then change its color to black and set its Alpha to 0, making it completely transparent.
The new gradient will therefore be bluish-green at the bottom and completely transparent at the top.
The blending of this effect with the others is done with a Color Mix node in Mix mode. Connect the first Color Mix node, which mixes CLOUDS and STARS, to the first input of the new Color Mix node.
Connect the output of the HORIZON-GLOW group to the second input of the new Color Mix node.
The output of the HORIZON-GLOW group should already be connected to an RGB TO BW node and a GAMMA node due to the duplication we performed earlier. Connect the output of the GAMMA node to the Factor input of the second Color Mix node. This time, I recommend a Gamma value of 0.5 or higher.
The output of the second Color Mix node can then be sent to the Background node, thus achieving the final effect, to which we will apply post-production to add a glow to the stars.
Before moving on to post-production to add some glow, I remind you that all the effects discussed so far have been created with procedural Textures, so it is possible to modify them and insert keyframes to create animations.
For example, we can provide Texture Coordinates and Mapping nodes to the Noise Texture that creates the clouds via the colored Color Ramp. Once done, it will be possible to animate the movement and change of the clouds by adjusting the Location and Rotation parameters of the new Mapping node.
There are various ways to animate the brightness of the stars.
For example, you can enter that group and insert a Color Mix node in Multiply mode with Factor set to 1 between the Gamma node and the group output. Then, add a procedural Magic Texture and connect the Factor output of the Magic Texture to the second image input of the newly created Color Multiply node.
Once this is done, you can animate the appearance of the Magic Texture in various ways, such as modifying its coordinates with Texture Coordinates and Mapping nodes, as done for the clouds, or simply animating the Scale parameter value of the Magic Texture.
This way, the Texture will move across the background and, when multiplied with the stars, will darken them randomly. However, this is just one of the possible methods by which you can vary the intensity of the stars in a random and animated manner.
Okay, now let's switch to a Compositing Layout and enable the Nodes for post-production.
Before starting the rendering, enable Emission and Environment in the Render Passes section of the View Layers tab in the Properties editor.
Add Viewer and Reroute nodes and enable the Backdrop button to preview the final effect after rendering.
Render the scene to obtain the Emission and Environment information and apply a glow and other effects to the rendering.
Add the Emission and Environment outputs of the Render Layers node together using a Color Mix node in Add mode with the Factor set to 1.
Connect a Glare node to the output of this node. In my case, I set it to Fog Glow mode with a low value for the Threshold parameter, high quality, Size 9, and most importantly, Mix set to 1. I've discussed the Mix parameter of the Glare node in several tutorials previously published on my channel, where I've shown that setting this parameter to 1 results in only the isolated Glare effect, which can be modified as desired.
Now you can add additional nodes to further modify the effect, such as Glare, Blur, or RGB Curves, as I did.
In any case, you will need to add the Glare effects obtained to the original rendering. This can be done using another Color Mix node in Add mode with a blending factor of 1. Connect the Image output of the Render Layer to the first Image input of the Add node.
Nothing prevents us from applying other effects after this mixing, such as brightness and contrast correction, or a final vignetting effect.
Now, we just have to render the animation and examine the resulting output.
Well, that's all for this tutorial! I hope you found it useful! See you soon!