7edf5bc4d0
Major updates: - Added 35+ new skills from awesome-opencode-skills and antigravity repos - Merged SEO skills into seo-master - Merged architecture skills into architecture - Merged security skills into security-auditor and security-coder - Merged testing skills into testing-master and testing-patterns - Merged pentesting skills into pentesting - Renamed website-creator to thai-frontend-dev - Replaced skill-creator with github version - Removed Chutes references (use MiniMax API instead) - Added install-openclaw-skills.sh for cross-platform installation - Updated .env.example with MiniMax API credentials
81 lines
3.0 KiB
Markdown
81 lines
3.0 KiB
Markdown
# Camera Effects Detailed Reference
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## Prerequisites
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- Ray marching fundamentals (ray origin, ray direction)
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- Multipass buffers (for accumulation-based DoF)
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- Hash functions for stochastic sampling
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## Thin Lens Model Derivation
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A real camera lens focuses light from a focal plane onto the sensor. Points not on the focal plane project to a **circle of confusion (CoC)** on the sensor.
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### Circle of Confusion Formula
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```
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CoC = |S2 - S1| × A × f / (S1 × (S2 - f))
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```
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Where:
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- `S1` = focal distance (distance to in-focus plane)
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- `S2` = object distance
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- `A` = aperture diameter
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- `f` = focal length
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### Simplified for Shaders
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```
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CoC ≈ apertureSize × |depth - focalDistance| / depth
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```
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### Ray-Based Implementation
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Instead of computing CoC per pixel, we model the physical process:
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1. Choose a random point on the aperture disk → new ray origin
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2. The focal point (where the original ray hits the focal plane) stays fixed
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3. New ray direction = `normalize(focalPoint - newOrigin)`
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4. Average many such samples → natural bokeh with correct occlusion
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### Aperture Shape
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- Circular: `vec2 p = sqrt(r) * vec2(cos(a), sin(a))` — uniform disk
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- Polygonal: reject samples outside polygon for hexagonal/octagonal bokeh
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- The `sqrt(r)` is critical for uniform distribution (area-preserving)
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## Poisson Disk Sampling
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Pre-computed 16-point Poisson disk for blur kernels:
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```glsl
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const vec2 poissonDisk[16] = vec2[](
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vec2(-0.94201624, -0.39906216), vec2(0.94558609, -0.76890725),
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vec2(-0.09418410, -0.92938870), vec2(0.34495938, 0.29387760),
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vec2(-0.91588581, 0.45771432), vec2(-0.81544232, -0.87912464),
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vec2(-0.38277543, 0.27676845), vec2(0.97484398, 0.75648379),
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vec2(0.44323325, -0.97511554), vec2(0.53742981, -0.47373420),
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vec2(-0.26496911, -0.41893023), vec2(0.79197514, 0.19090188),
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vec2(-0.24188840, 0.99706507), vec2(-0.81409955, 0.91437590),
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vec2(0.19984126, 0.78641367), vec2(0.14383161, -0.14100790)
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);
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```
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Advantages over regular grid: no structured aliasing patterns, better coverage per sample count.
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## Motion Blur Approaches
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### Stochastic Time Sampling (Ray Marching)
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For each pixel, pick a random time within the shutter interval:
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```
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t_sample = iTime + (rand - 0.5) * shutterDuration
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```
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Use `t_sample` for all scene animation. Accumulate multiple frames for convergence.
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### Velocity Buffer (Post-Process)
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1. Render scene + store per-pixel velocity vectors
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2. For each pixel, sample along the velocity direction
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3. Weight samples by distance from center (triangle filter)
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### Hybrid
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Use temporal accumulation (TAA-style) with per-frame time jitter — converges over frames with no per-frame cost increase.
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## Film Grain Characteristics
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Real film grain properties:
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- **Luminance-dependent**: More visible in shadows, less in highlights
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- **Temporally varying**: Different pattern each frame (use `fract(iTime)` in hash seed)
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- **Spatially uncorrelated**: Use pixel coordinates in hash, not UV (grain should be screen-resolution)
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- **Intensity**: 0.02-0.05 for subtle, 0.1+ for stylized/vintage look
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