Glow
The Glow shader creates a bloom lighting effect by extracting bright areas, blurring them, and compositing them back over the original image. It uses a 3-pass rendering pipeline for high-quality results.
Parameters
Threshold
| Range | Default | Step |
|---|---|---|
| 0–1 | 0 | 0.1 |
Controls which pixels are bright enough to glow. Only pixels with luminance above this threshold contribute to the bloom.
| Value | Behavior |
|---|---|
| 0 | Everything glows — the entire image contributes to bloom |
| 0.3 | Moderate — mid-to-bright areas glow |
| 0.7 | Selective — only the brightest areas produce bloom |
| 1.0 | Nothing glows (effectively disabled) |
Radius
| Range | Default | Step |
|---|---|---|
| 1–200 | 48 | 1 |
The size of the bloom blur kernel in pixels. Larger values produce a wider, softer glow.
Intensity
| Range | Default | Step |
|---|---|---|
| 0–10 | 2 | 0.1 |
Brightness multiplier for the bloom. Higher values make the glow more prominent.
Color Mode
| Value | Effect |
|---|---|
| Source | Glow uses the original pixel colors — bright areas bloom in their natural color |
| Gradient | Glow is tinted using a custom color with adjustable hue/saturation shift |
Blend Mode
| Value | Effect |
|---|---|
| Screen | Additive blending — glow brightens the image (default, natural bloom look) |
| Add | Pure addition — can push values past white for a more intense look |
Color Shift (Gradient mode only)
| Range | Default | Step |
|---|---|---|
| 0–1 | 0 | 0.1 |
When color mode is set to Gradient, this shifts the glow color through the hue spectrum. Use the color picker to select a base glow color, then adjust this value to shift it.
Use the color picker (visible when color mode is set to Gradient) to choose the exact glow tint color. This uses the app's standard color picker component.
Keyframing
All numeric parameters support smooth interpolation:
- Animate threshold to reveal bloom gradually
- Animate intensity for pulsing glow effects
- Animate radius to expand or contract the bloom over time
- Color mode and blend mode use hold interpolation
Use Cases
- Neon text — Low threshold (0.1), moderate radius (30–60), high intensity (3–5) with gradient color mode
- Soft dreamy look — Threshold 0, large radius (80+), low intensity (0.5–1)
- Highlight emphasis — High threshold (0.5–0.7) to only bloom the brightest elements
- Pulsing energy — Keyframe intensity between 1 and 5 in a loop
- Color wash — Gradient mode with color shift animation
Technical Notes
- 3-pass pipeline: luminance threshold extraction → horizontal Gaussian blur → vertical Gaussian blur with composite
- Uses a dedicated snapshot texture to preserve the original image for compositing — this ensures correct results regardless of position in the shader stack
- The bloom is composited back onto the original using the selected blend mode
- Radius affects GPU performance — very large values (150+) require more texture samples per pixel