Defold Deferred Lighting Example

Author: https://t.me/martianov

This project demonstrates a full deferred rendering pipeline in Defold with support for G-buffer, SSAO, point light shadows, volumetric light, and filmic tonemapping. You can use the project as a foundation for your own scenes and renderers.

Features

• G‑Buffer: writing albedo, normals (oct-encoding), and depth into separate buffers for subsequent lighting.
• SSAO: screen-space ambient occlusion with position reconstruction from depth, oriented kernels, and smoothing.
• Point light shadows: rendering shadow cubemaps into an atlas (6 faces per light).
• Volumetric light: simple integration of scattering along the camera ray, light “glow”.
• PBR lighting (simplified): Lambertian diffuse + base F0, BRDF stubs.
• Filmic tonemapping: gentle mapping of HDR lighting into LDR.
• Render scaling: automatic resizing of targets to the window size.
• Flexible scene: free-fly camera, multiple point lights, a set of objects and materials.

How it works (pipeline)

Rendering is performed in several passes and assembled in render.render_script:

1. G‑Buffer (Assets/Materials/Deferred/GBuffer/*)
   • In GBuffer.fp albedo is sampled from a texture, the normal is reconstructed from a normal map in world space and encoded into 2 channels (oct-encoding, see Modules/NormalCoder.glsl). In GBuffer.vp varyings and matrices are prepared.
   • Result: COLOR0 = albedo (premultiplied alpha), COLOR1 = normals.xy + roughness.z, DEPTH = depth.
2. Cubemap shadows (Assets/Materials/Deferred/DepthPass/*)
   • For every point light, 6 faces are rendered into the shared atlas using RenderScriptToolkit.render_multi_cubemap and the DepthPass material.
3. SSAO (Assets/Materials/Deferred/SSAOPass/*)
   • In SSAOPass.fp position is reconstructed from depth, normals are decoded; random directions are chosen from the kernel/noise (Modules/SSAOUtils.lua generates u_ssaoKernel/u_ssaoNoise). The output is a single‑channel AO map.
4. Lighting (Assets/Materials/Deferred/LightingPass/*)
   • In LightingPass.fp world positions are reconstructed, normals are decoded, SSAO is applied, arrays of light sources are iterated, BRDF is evaluated, shadows are applied (see modules in Assets/Materials/Deferred/Modules/*), volumetric light and tonemapping are applied.
5. Composition to screen
   • The lighting result is output to a separate render target and then drawn onto the RenderRoot sprite stretched to the window size.

Project structure

• render.render_script — the main render script. Manages targets, passes, materials, and ties all pipeline stages together.
• Render.render — the list of materials attached to the render script.
• Modules/Render/Backend/
  • Nodes/RenderRoot.* — wrapper node for presenting the final image; reacts to window resize and reports it to the renderer.
  • Modules/RenderScriptToolkit.lua — rendering utilities: create/bind targets, draw fullscreen quad, render cubemaps, etc.
  • Modules/Camera.lua — simple camera with perspective projection and frustum update.
  • Modules/SSAOUtils.lua — kernel and noise generation for SSAO.
  • Materials/RenderRoot.*, Shaders/RenderRoot.* — material/shaders of the screen sprite.
• Modules/Render/Scene/
  • Nodes/Camera.go + Camera.script — free‑fly camera (WASD + mouse), sends camera_update to the renderer.
  • Nodes/Light.go + Light.script — point lights (color, intensity, radii), send create_point_light to the renderer.
  • Materials/Billboard.* — light icon visualization.
• Assets/Materials/Deferred/
  • GBuffer/*, SSAOPass/*, DepthPass/*, LightingPass/* — materials and shaders of all passes.
  • Modules/*.glsl — reusable GLSL modules: normal encoder, lighting utilities, SSAO, shadows, volumetric light, filmic, etc.
• Objects/* — example scene objects (models, materials with albedo/normal/roughness).
• Main.collection — scene with camera, lights, level meshes, and attached RenderRoot.

Data flow and key constants

• Messages to the renderer:
  • camera_update — camera view/projection matrices and transform.
  • set_render_size — new window size → re‑create/resize targets, update projection.
  • create_point_light — add a point light (position, color, intensity, radii).
• Buffers:
  • camera_render_target (G‑Buffer): COLOR0 albedo, COLOR1 normals+roughness, DEPTH depth.
  • ssao_render_target: AO map at half resolution.
  • light_shadowmap: shadow cubemap atlas RGBA32F + DEPTH.
• Light arrays (in LightingPass.fp): light_position_array, light_color_array, light_properties_array (intensity, surface radius, volume radius).

How to run

1. Open the project in Defold.
2. Make sure Main.collection is the startup collection.
3. Run the project. The camera is controlled by WASD + mouse (sensitivity/speed in Modules/Render/Scene/Nodes/Camera.script).
4. Window resize automatically rebuilds render targets; the final image is stretched onto RenderRoot.

How to add your own object/material

• Add a model to Assets/Meshes and PBR textures (albedo/normal/roughness) to Assets/Textures.
• Define a material in Assets/Materials/Scenes/model.material and bind textures to samplers albedo, normal, roughness.
• Create a GO/collection in Objects and place it into Main.collection.

Quality and performance

• Currently, shadows are rendered in real time and for all light sources. For optimization, you can later refine this so that shadows are not processed for some lights, or are rendered only when the player is nearby.
• Reduce ssao_render_target size to speed up SSAO.
• Reduce light_shadowmap size or the number of light sources.
• Limit light_count or use clustering/tiling (future work).
• Move part of calculations to half‑precision where possible.

Known simplifications

• Shadows: basic sampling without PCF/PCSS filtering (configured in lighting_shadow.glsl).
• BRDF: simplified diffuse, without a full metallic/specular pipeline.
• Volumetric light: simplified integration, without multi‑sample phase functions and multiple scattering.

License and acknowledgements

Use freely for educational and prototyping purposes. Textures and models are taken from publicly available sources — check their licenses when distributing.