Karl
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hexaquo.at
Karl
@hexaquo.at
1.3K followers 950 following 210 posts
Researcher, teacher and activist somewhere at the intersection of landscape perception, graphics programming, open source, and climate change.

Working on VR landscape visualization with Godot. Maintaining Geodot: https://github.com/boku-ilen/geodot-plugin
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hexaquo.at
#godot #gamedev
Screenshot of a landscape rendered in Godot. View into a hilly landscape from a field track next to a sunflower field, with a small tree in the middle. The sun is fairly low. View up into the sky with a branch in the foreground and another tree in the distance. The sun is visible and creates some slight lens flares. View into the distance onto an expansive, slightly hilly landscape, with different agricultural fields. A few birds are flying in the distance. View over a field onto a village. The sun is low, creating a golden light.
January 13, 2026 at 3:24 PM
hexaquo.at
Thanks, yeah feel free to take any code that's useful! I can get some nice anamorphic glare with the right settings; if you also want to stretch the lens flare ghosts, you could probably apply the glare blur filter (streak.glsl in my repo) to the buffer used for the ghosts. (or just warp the UVs)
Screenshot of the Godot editor with the sun producing a strong horizontal anamorphic glare. To the right, the corresponding settings are visible under the "Glare" tab": Streak count 2, attenuation 0.992, samples 6
January 8, 2026 at 3:20 PM
hexaquo.at
January 8, 2026 at 12:28 PM
hexaquo.at
#godot #gamedev
January 8, 2026 at 12:28 PM
hexaquo.at
Lens Flare update: exposed all configurable parameters now. There's probably still a lot of potential for performance optimization, but I'd say it's somewhat usable :)

You can check it out here, should work in any project (though requires some HDR care):
github.com/kb173/godot-...

#Godot #gamedev
December 29, 2025 at 2:30 PM
hexaquo.at
If you want your #Godot game to look like Battlefield 3, I got you
Screenshot of a Godot scene with a blue sky and the sun visible through a large window in a concrete structure. The sun (and a reflection of the sun on the concrete) have a strong glare with 6 light streaks going outwards. There is also a lens flare effect with chromatic aberration, and the bloom uses a lens dirt texture to create large circular patterns of higher brightness (like dust on a lens).
December 23, 2025 at 1:21 PM
hexaquo.at
December 18, 2025 at 9:55 PM
hexaquo.at
More work on procedural lens flares in #Godot.

If you want to have a look at the (still very messy!) code: github.com/kb173/godot-...

Outline of how it works:
1. Clip bright spots from the rendered image
2. Warp these spots to create ghosts and a halo
3. Blur
4. Overlay based on a dirt texture
December 18, 2025 at 9:55 PM
hexaquo.at
Finally learning CompositorEffects #Godot

Lens flare based on this blog: john-chapman-graphics.blogspot.com/2013/02/pseu...
December 16, 2025 at 5:49 PM
hexaquo.at
I often talk about bent normals for billboards, and I keep having to mention the "if (!FRONT_FACING) NORMAL = -NORMAL" workaround for correct backface lighting. I realized I could fix that myself, so I opened a PR for an intuitive material option and render_mode:
github.com/godotengine/...
#Godot
Left: a plane and a sphere with billboards scattered on it. A text below says "Default", and some billboards are noticeably darker than the others. Right: the same plane and sphere with billboards, but with smooth lighting without the dark billboards. The text below says "Keep Backface Normals". Schematic drawing. Left, titled "Original normals, matching geometry": a plane with an arrow pointing orthogonally outwards to the right, saying "original normal", and an arrow pointing into the opposite direction, saying "default behavior: flipped normal". Right, titled "Custom normals, do not match geometry": a plane with an arrow pointing straight up, parallel to the plane, saying "original normal", and the same arrow again, saying "intended backface normal". Another arrow points straight down, saying "default behavior: flipped normal".
November 26, 2025 at 4:19 PM
hexaquo.at
on my way to #GodotFest! hope to meet some of you there :)
Laptop on a desk in a train next to a window. A presentation is being edited on the laptop. Outside the window are houses and hills lit by sunset. View out of the train window. A church can be seen on a nearby hill, which is otherwise covered by forest.
November 10, 2025 at 3:41 PM
hexaquo.at
🔜 #GodotFest

Want to see these slides (and many more) live? Then join my presentation on November 11th at GodotFest in Munich :)

#godot #gamedev
Presentation slide with the text "Plants, Polygons and Pixels: Large-Scale Vegetation Rendering in Godot". The background is a slightly blurred view over a rendered landscape. Presentation slide with the text "Geometry versus Billboards". "Geometry" is bold. On the right, a highly detailed 3D model of a tree is shown, first rendered, then shaded in white to show the intricate geometry. Presentation slide with the text "bend your normals!" and two rendered trees. The tree on the right has a clearer canopy shape due to smoother lighting. An arrow points from the left to the right tree. Presentation slide with the text "Ground-Covering Billboard Clouds" and an image of a rendered landscape. In the right half of the rendering, the plant billboards are rendered as white quads in order to show the geometry.
October 21, 2025 at 3:07 PM
hexaquo.at
The idea is: make the vertices stick to the camera rather than passing behind it, and use alpha to make these vertices fade out as the camera is moving through the mesh.
Schematic drawing. Left, labeled "before", shows a camera (depicted as a triangle) inside a circle. Right, labeled "after", shows the camera next to a half-circle, the wall of which is right in front of the camera. Screenshot of Godot shader code: shader_type spatial; uniform float radius = 2.0; varying float inside_alpha_factor; // I think you could get this out of the PROJECTION_MATRIX, but I was too lazy to figure that out #define CAMERA_NEAR -0.051 void vertex() { // Transform vertex from model space into view space vec3 view_vertex = (MODELVIEW_MATRIX * vec4(VERTEX, 1.0)).xyz; // Calculate a factor which goes from 1.0 (when the camera is in front of the original vertex // position, i.e. the vertex is right on the near plane in view space) to 0.0 (when the vertex // is radius * 2.0 behind the camera, i.e. we're at the opposite end of the mesh) inside_alpha_factor = smoothstep(radius * 2.0, CAMERA_NEAR, view_vertex.z); // Stick the vertex right onto the camer's near plane view_vertex.z = min(view_vertex.z, CAMERA_NEAR); // Transform back to model space and assign to VERTEX VERTEX = (inverse(MODELVIEW_MATRIX) * vec4(view_vertex, 1.0)).xyz; } void fragment() { // Apply the alpha ALPHA = inside_alpha_factor; }
October 4, 2025 at 4:47 PM
hexaquo.at
This got me wondering what would be the easiest way to make meshes appear like a volume when moving through them (using only shaders). This is what I came up with:
October 4, 2025 at 4:47 PM
hexaquo.at
In the visualization project I work on I do something very similar: fade the billboard vegetation into an impostor which is a "Next Pass" of the clipmap terrain - same geometry, but moved up to match the plant height and textured by mashing the local plants' billboard textures together.
Screenshot of a landscape visualization at eye-level. There's a vegetable field underneath the camera; the landscape gently slopes downward into a meadow, until it slopes up again on a sparsely forested hill. A power pole sits on top of the hill and cables go from the left to the right of the image. Three wind turbine rotors can be seen in the distance on the left. Same screenshot as before, but annotated with a line. A text identifies the area above the line as "low LOD impostor" and the area under the line as "high LOD billboards"; the line delineates the approximate border where the high LOD is blended into the low LOD.
August 25, 2025 at 8:49 PM
hexaquo.at
After some theory about LOD, I go over my approach to creating impostors for foliage, sharing some trickery I've learned over time. The result is a plane which behaves very similar to the grass geometry, without actually having any extra geometry.

Please reach out if anything is unclear or missing!
Comparison of a mesh (a lion bust) at different levels of detail. The top shows 3 versions of the mesh at descending LOD shaded normally, the bottom shows a wireframe view of the same meshes. In the middle, the triangle count of the meshes is written: the highest LOD contains 33536 triangles, the medium LOD 1047 tris, the lowest LOD 132. Unshaded view of the high-LOD grass geometry next to the grass impostor plane. The screenshot shows off how the impostor has black spots, simulating the ground showing through in-between grass-blades, like the real geometry. A rather noisy screenshot of the impostor grass' normal map (left) and the normals of the real grass geometry (right); they look very similar. Fully shaded view comparing the grass impostor plane (left) to the real grass geometry (right). Although the plane is visibly flat, the colors and shading match the real grass closely.
August 25, 2025 at 4:18 PM
hexaquo.at
Finally finished part 4 of my Godot Grass Rendering Series! In this one, we'll dive deep into level-of-detail and impostors to create an infinite field of grass while keeping the GPU cool:

hexaquo.at/pages/grass-...

#godot #gamedev
August 25, 2025 at 4:18 PM
hexaquo.at
New tutorial blog post!
Environment and Light in Godot: Setting Up For Photorealistic 3D Graphics

hexaquo.at/pages/enviro...

I've been meaning to write this for a while, both as an overview over Godot's Environment, and as an entry point to realistic 3D graphics.

#godot #gamedev
Demo scene in Godot consisting of a simple concrete structure with two windows walls and a tree. Godot's default environment is applied, making the scene look a bit unimpressive. Screenshot of the same demo scene from the same perspective, but with better lighting and more vivid colors. Same demo scene viewed from a slightly steeper angle, making the ground reflect more light and showing more of the sky through the window. Demo scene viewed from the back, making branches of the tree visible through the concrete window.
August 17, 2025 at 5:33 PM
hexaquo.at
Vineyards

#godot #gamedev
Virtual 3D landscape depicting rows of wine on a gentle hill; the camera is right in front of the rows View of a virtual vineyard from a distance; there's an acre in the foreground
August 3, 2025 at 9:38 PM
hexaquo.at
Your game looks interesting, are the facades from street-level images? The roads and rails (which I saw in a screenshot you posted before) look similar to the ones in our landscape visualization.
Screenshot of a realistic-looking 3D scene. The camera is standing on a bridge at eye-level, half of the street and the guardrail and fencing can be seen. In the distance, there is a channel and some buildings. Screenshot of a realistic-looking 3D scene. A railway curves through a steep forest. A high and steep mountain can be seen in the distance.
July 26, 2025 at 9:10 PM
hexaquo.at
Larger asphalt roads do exist as thin 3D objects, but they also alter height and foliage for a banquet and a smooth transition.
Screenshot of an empty gravel path Screenshot of the same perspective, but there is now a road on the gravel path; the terrain has been slightly altered to accommodate the street, and it's delineated with a guard rail.
July 17, 2025 at 2:11 PM
hexaquo.at
I've been working on our road system, which can now alter both terrain and foliage in real-time. Country lanes like this don't exist as actual objects, they just write into the terrain offset and foliage maps.
Screenshot of the country lane seen in the video, but instead of the detailed country lane, it's only an empty gravel path, since the country lane renderer has been disabled. Screenshot of the country lane seen in the video, in full detail again.
July 17, 2025 at 2:11 PM
hexaquo.at
Afternoon stroll

#godot #gamedev
July 17, 2025 at 2:11 PM
hexaquo.at
Screenshot of the game "Just Grandma and Me": a cartoon drawing in which the eponymous grandma and her grandkid are leaving a garden onto a street, with a house on a hill in the background. There's a text saying " We went to the beach, just Grandma and me.". At the bottom there is a language selection UI (English, French, Spanish, German).
July 13, 2025 at 7:31 AM
hexaquo.at
This article is a great overview on texture padding! I've also done a thread on it here when I found out how important it is for billboard plants; I ended up using GMIC's solidify algorithm, which works well for noisy plant textures made from photographs. Here's the script and the before/after:
Screenshot of the following bash script: gmic -input $1 -solidify 75 -output out.png magick $1 -alpha extract alpha.png magick out.png -alpha on \( +clone -channel a -fx 0 \) +swap alpha.png -composite $1 rm out.png alpha.png Texture of multiple poppy plants. The background (which is usually transparent) is black, as is default when exporting from image processing software like GIMP. Same texture of multiple poppy plants. The background (which is usually transparent) is now a blur of the nearby non-transparent colors, causing the top of the image to be mostly red (from the poppy flowers) and the middle and bottom to be a mix of greens.
July 12, 2025 at 7:36 PM