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Custom C++ Terrain Editor

January 24, 2025

Custom C++ Terrain Editor was a solo research project. The project features editable terrain and variety of brushes. The Terrain Editor would later become based for the Fire Ant Engine.

My Contributions: Terrain Mesh Deformation via Height Maps | Vertex Shader with Dynamic Normals & Displacement | Fully Custom Brush Framework | Normals-based Object Placement

Engine/Tools: C++, OpenGL, GLSL (Vertex & Fragment Shaders), ImGui, GLM

Team Size: Solo

Platforms: Windows

Duration: 8 weeks (Nov 2024 - Jan 2025)

🏔️ Terrain Editor – My Contributions

🔍 What It Does

The Custom C++ Terrain Editor is a solo-developed terrain sculpting tool and rendering system built in C++ using OpenGL. It enables real-time terrain editing via an intuitive brush interface, allowing users to raise/lower terrain, flatten areas, smooth contours, and scatter foliage—all with visual feedback. It also includes dynamic heightmap-based terrain rendering and an interactive camera system for navigation.

This project served as the predecessor to the Terrain Editor in Fire Ant, laying the groundwork for compute-driven tools and brush architecture used in later engine projects.

I have written a blog post about the project here.

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🔨 My Contributions

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🌄 Terrain Rendering

I built a full rendering pipeline for heightmap-displaced terrain using a custom vertex shader that dynamically adjusts vertex positions based on height texture values.

Key Features:

• Real-time terrain displacement using heightmap textures.
• Per-pixel normal calculation in vertex shader using height differentials.
• Visual terrain sculpting directly reflected in mesh deformation.

Challenges:

• Implementing dynamic normals in shader for accurate lighting.
• Encoding and decoding 32-bit float height values in RGBA textures.
• Integrating seamlessly into the existing BEE rendering system.

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🖌️ Brush System

I developed a fully functional brush-based editing interface that modifies terrain heightmap data in real time. Each brush operates on a targeted region and modifies texture data on the CPU before uploading it back to the GPU.

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🧱 Raise and Lower Brush

What It Does: Raises or lowers terrain in a circular region using a Gaussian distribution, with optional “average terrain” filtering to sculpt only selected elevations.

Key Features:

• Brush size controlled via GUI and keyboard shortcuts ([ and ]).
• Gaussian falloff for natural hills and valleys.
• Optional averaging mode for smoother sculpting.

Challenges:

• Precision sampling and modification of texture regions.
• Efficient GPU upload via glTexSubImage2D.
• Integrating user-defined intensity, radius, and direction.

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🏔️ Plateau Brush

What It Does: Flattens terrain within the brush area to a target height—either manually set or sampled from the terrain via mouse click.

Key Features:

• Terrain sampling for real-time height targeting.
• Sharp yet smooth edges using distance-based Gaussian blending.
• Adjustable brush shape and diameter.

Challenges:

• Real-time sampling and synchronization between UI and edit operations.
• Balancing falloff and accuracy to prevent unnatural flat zones.

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🧩 Smoothing Brush

What It Does: Averages surrounding terrain to eliminate sharp edges and create smooth transitions between sculpted features.

Key Features:

• Computes average height of brush region and nudges local points toward it.
• Effective for softening harsh elevation changes.

Challenges:

• Preventing over-smoothing and maintaining natural detail.
• Efficient height sampling and buffer handling.

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🌳 Foliage Brush

What It Does: Spawns props (like trees) along terrain, with random scattering and optional alignment to terrain normals.

Key Features:

• Real-time prop spawning based on brush area.
• Placement along surface normals using dynamic heightmap-based normal calculation.
• Supports arbitrary models (trees, rocks, etc.).

Challenges:

• Calculating normals in CPU-space based on sampled height differences.
• Aligning rotation to match surface orientation (quaternion math).
• Managing object instancing and entity creation.

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🕹️ Camera System

I implemented a free-fly 3D camera system with full keyboard and mouse support to allow intuitive navigation across the terrain.

Key Features:

• WASD + QE movement controls with Shift-based speed boost.
• Mouse-based pitch and yaw using quaternion math.
• Camera frustum integration for viewport interaction.

Challenges:

• Handling mouse sensitivity and orientation smoothly across all axes.
• Ensuring intuitive controls within an ImGui-driven editor.

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🧠 Key Engineering Techniques

• Raycasting from screen to world space for accurate brush placement.
• UV coordinate derivation from 3D brush position to texture space.
• Brush zone sampling & editing using bounding box logic on heightmaps.
• Efficient GPU I/O via partial glTexSubImage2D updates.
• Gaussian weight distribution for natural deformation.
• Normal vector reconstruction from sampled height gradients.

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🎯 Impact

This project taught me the fundamentals of shader-based terrain deformation, interactive editor systems, and real-time tool development. It directly led to major architectural improvements in later projects like the Terrain Editor in Fire Ant.

My brush system, heightmap-based editing, and real-time feedback loop laid a reusable foundation for more scalable GPU-powered editing tools.