Forker Renderer: CPU-Based Forward / Deferred Rasterizer, A Tiny OpenGL 🐼

Implemented a CPU-based software rasterizer that simulates how OpenGL works without using any third-party libraries but using gabime/spdlog for logging though :)

🔨 Building & Usage

# Clone
git clone https://github.com/forkercat/ForkerRenderer.git
cd ForkerRenderer 

# Compile
mkdir build && cd build
cmake .. && make

# Usage: <scene filename>
./ForkerRenderer ../scenes/test.scene

🥺 Future Development

• Physically-Based Rendering (PBR)
  • Improvement
• Global Illuminations
  • Screen Space Reflection (SSR) aka. Realtime Ray Tracing

⭐ Features

• Rasterization
  • Bresenham's Line Algorithm (used and removed)
  • Bounding Box Method (currently used)
• Rendering Methods
  • Forward Rendering
  • Deferred Rendering
    • G-Buffers: depth, world position, normal, albedo, etc
    • Geometry Pass
    • Lighting Pass

• Shading
  • Depth Shading
  • Geometry Shading (for deferred rendering)
  • Blinn-Phong Shading
  • PBR Material and Shading
    • Cook-Torrance reflectance equation
    • D: Trowbridge-Reitz GGX
    • F: Fresnel-Schlick approximation
    • G: Smith's method with Schlick-GGX

• Parsing *.obj / *.mtl
  • g defines mesh name; usemtl defines m_Material name (comes in order)
  • Support Ka, Kd, Ks, Ke, map_Kd, map_Ks, map_Ke, map_Bump, map_Ao, map_Pr, map_Pm
  • Position vertex normalization
  • Auto triangulation
• Parsing scene files *.scene

# Test Scene
screen 1280 800
# forward/deferred rendering
mode deferred
ssaa off 2
shadow on
# Light (type: point/dir, position, color)
light point 2 5 5 1 1 1
# Camera (type: persp/ortho, position, lookAt)
camera persp -1 1 1 0 0 -1
# Models (filepath, position, rotate_y, uniform scale)
model obj/plane/plane.obj false false 0 -1 -1 0 3
# Mary
model obj/mary/mary.obj true true 0.05 0 -1 -10 1

• Geometry Template Class
  • Vector: Vector2f, Vector3f, Vector4f, Vector4i, ...
  • Matrix: Matrix3f, Matrix4f, Matrix3x4f, ...
  • Support glm-style vector swizzling, e.g. v.xyz, v.xy
• Light: Point / Directional
  • AreaLight is defined by AREA_LIGHT_SIZE in shadow mapping)
• Texture Mapping:
  • Diffuse / Specular / Normal / Emissive
  • Roughness / Metalness / Ambient Occlusion
• Texture Wrapping: NoWrap / ClampToEdge / Repeat / MirroredRepeat Texture::WrapMode
• Texture Filtering: Nearest / Linear (Bilinear) Texture::FilterMode

• Normal Transformation: TBN Matrix
  • Generate and average m_Tangents for each vertex when loading the model
• Camera: Orthographic / Perspective Projection
• Perspective Correct Interpolation (PCI) #define PERSPECTIVE_CORRECT_INTERPOLATION

• Shadow Effect
  • Hard Shadow: Shadow Mapping (set shadow on in test.scene and comment out below macros)
  • Soft Shadow:
    • Percentage-Closer Filtering (PCF) #define SOFT_SHADOW_PCF
    • Percentage-Closer Soft Shadow (PCSS) #define SOFT_SHADOW_PCSS

#ifdef SOFT_SHADOW_PCF
    // Percentage-Closer Filtering (PCF)
    visibility = PCF(uShadowBuffer, shadowCoord, bias, PCF_FILTER_SIZE);
#elif defined(SOFT_SHADOW_PCSS)
    // Percentage-Closer Soft Shadow (PCSS)
    visibility = PCSS(uShadowBuffer, shadowCoord, bias);
#else
    // Hard Shadow
    visibility = HardShadow(uShadowBuffer, shadowCoord, bias);
#endif

• Anti-Aliasing (AA)
  • SSAA: Super-Sampling Anti-Aliasing (set ssaa on in test.scene)
  • MSAA: Multi-Sample Anti-Aliasing

• Global Illuminations
  • Screen Space Ambient Occlusion (SSAO) ssao on
    • Range Check (courtesy of John Chapman)
    • Noise Reduction: simple 9x9 blur, two-pass Gaussian blur
  • Screen Space Reflection (SSR)
    • Aka. Screen Space Ray Tracing

🖼️ Gallery

Apex Horizon (also Dr. Mary Somers) [Squral]

Mary [TAs from GAMES202: Real-time High Quality Rendering]

Horizon Meets Mary

Sci-Fi Welding Vehicle [Berk Gedik]

Cafe Menu Chalkboard [Naiyararahman]

Gossblade Greatsword (Monster Hunter Rise) [taj_tajima]

Backpack [Berk Gedik]

African Head [Vidar Rapp]

📁 Structure

About 5,500 lines of code:

• Rendering: render.h/cpp (rendering functions), forkergl.h/cpp (rasterization)
• Buffer: buffer.h/cpp (Buffer1f, Buffer3f)
• Shader: shader.h, phongshader.h, pbrshader.h, depthshader.h, gshader.h
• Shadow: shadow.h/cpp
• Scene: scene.h/cpp, scenes/test.scene
• Model: model.h/cpp, mesh.h/cpp, material.h, pbrmaterial.h, texture.h
• Camera: camera.h/cpp
• Light: light.h
• Color: color.h
• Geometry: geometry.h/cpp
• Utility: tgaimage.h/cpp, output.h/cpp, check.h, utility.h, constant.h, stringprint.h (PBRT-v3)

📜 Console Output

$ ./ForkerRenderer scenes/test.scene
[info] Scene File: 'scenes/test.scene'
[info]   [Mode] Forward Rendering
[info]   [Screen] 1280 x 800
[info]   [Point Light] position: [ 2.00000000, 5.00000000, 5.00000000 ], color: [ 1.00000000, 1.00000000, 1.00000000 ]
[info]   [Camera] position: [ -1.00000000, 1.00000000, 1.00000000 ], lookAt: [ 0.00000000, 0.00000000, -1.00000000 ]
[info]   [Model] 'obj/diablo_pose/diablo_pose.obj'
[info]      v# 2519, f# 5022, vt# 3263, vn# 2519, tg# 2519, mesh# 1, mtl# 1 | normalized[o] generateTangent[o], flipTexCoordY[o]
[info]      [Diablo_Pose] f# 5022 | PBR[x] map_Kd[o] map_Ks[o] map_Ke[x] map_Bump[o] | Ka(0.10, 0.10, 0.10), Kd(0.81, 0.81, 0.81), Ks(0.20, 0.20, 0.20)
[info]   [Config] SSAA(x2)[off] shadow[on] SSAO[off]
[info] ------------------------------------------------------------
[info] Time Used: 0.714729 Seconds (Scene Loaded)

[info] Shadow Pass:
[info]   [Status] Enabled
[info]   [Diablo_Pose] Time Used: 0.106988 Seconds
[info] ------------------------------------------------------------
[info] Time Used: 0.858756 Seconds (Shadow Pass)

[info] Forward Pass (Blinn-Phong):
[info]   [Diablo_Pose] Time Used: 3.92819 Seconds
[info] ------------------------------------------------------------
[info] Time Used: 3.97755 Seconds (Forward Pass)

[info] Anti-Aliasing (SSAA):
[info]   [Status] Disabled
[info] ------------------------------------------------------------
[info] Time Used: 4.87400e-06 Seconds (Anti-Aliasing)

[info] Output TGA File: 'output/framebuffer.tga'
[info] Output TGA File: 'output/shadowmap.tga'
[info] Output TGA File: 'output/zbuffer.tga'

📚 References

Started by following the basic workflow in ssloy/TinyRenderer, improved code style (e.g. geometry.h) when referring to other great resources such as mmp/pbrt-v3 & v4, and resolved tons of issues with the help of the Internet. Thank those authors and creators who wrote the articles and built the models!

Rendering:

• ssloy/TinyRenderer
• mmp/pbrt-v3 & v4
• lingqi/GAMES101
• lingqi/GAMES202
• Scratchapixel
• JoeyDeVries/LearnOpenGL
• OpenGL Projection Matrix
• The Normal Matrix
• Perspectively Correct Texture Mapping And color Interpolation
• Converting quadrilaterals in an OBJ file into triangles?
• OBJ FILE FORMAT
• Object Files (.obj)
• More and more articles...

Model Credits:

• Apex Horizon by Squral
• Sci-Fi Welding Vehicle by Berk Gedik
• Backpack by Berk Gedik
• African Head by Vidar Rapp
• Diablo Pose by Samuel (arshlevon) Sharit
• Mary by TAs in GAMES202: Real-time High Quality Rendering
• Cafe Menu Chalkboard by Naiyararahman
• Gossblade Greatsword by taj_tajima
• Brickwall, Plane, Catbox (for debugging) by MYSELF! :)