Blossom 🌸

Blossom is a small framework for creating 4K Executable Graphics artworks for the demoscene.

You are free to use this as the basis for your own demoscene works; credit ("Blossom by yx") is welcome but not required.

Rendering Model

Blossom is built primarily with accumulative pathtracing in mind. There are two shaders, draw and present. The draw shader will be executed repeatedly up to a configurable sample-count or render duration, and each sample will be additively blended into a framebuffer. Once the samples are all accumulated, the present shader will be executed repeatedly until the user exits the program. Typically the present shader will sample the result of the accumulated draw passes, and perform some sort of post-processing, tonemapping, etc. for display.

In the example shaders provided, the alpha channel of the draw buffer is used to keep track of the sample count (by writing an additive 1.0 for each sample).

Configurations

Debug

Does what it says on the tin - a debug-friendly mode, no executable compression (although shaders are still minified). By default this will open a smaller 1280x720 window, and a progressive rendering preview will be enabled. A debug console window is also available.

Release

This builds the executable with Crinkler enabled to shrink it as small as possible.

Capture

No minification, but the executable will save the rendered image out to a file, and then exit.

Shader Uniforms

vec4 iResolution

The target resolution, available in both shaders.
x and y components are the width and height respectively.
z and w contain the aspect ratio (width/height) and inverse aspect ratio (height/width) respectively.

int iFrame

The current sample index, only available in the draw shader.

sampler2D accumulatorTex

The accumulation framebuffer, only available in the present shader.

Custom Options

In config.h, there are a number of customization options for you to set how you see fit:

WINDOW_FULLSCREEN

If enabled, Blossom opens in exclusive-fullscreen, otherwise it opens a borderless window.

WINDOW_AUTO_SIZE

If enabled, Blossom will target the primary display's native resolution. Otherwise, the target resolution must be set explicitly with CANVAS_WIDTH and CANVAS_HEIGHT.

Note: If you enable WINDOW_AUTO_SIZE but your artwork needs to be presented in a certain aspect ratio, it's up to you to handle appropriate letterboxing/pillarboxing manually in your shader code - Blossom will not handle that for you.

CANVAS_WIDTH, CANVAS_HEIGHT

Specify the target resolution in pixels. Only used if WINDOW_AUTO_SIZE is disabled.

RENDER_MAX_TIME_MS

Specify the maximum rendering time in milliseconds. Recommended for compo use.

RENDER_MIN_SAMPLES

Optional. Specify the minimum number of samples to accumulate.

RENDER_MAX_SAMPLES

Optional. Specify the maximum number of samples to accumulate. Recommended for compo use, if you don't need a high sample count to converge your artwork.

RENDER_EXACT_SAMPLES

Specify an exact number of samples to accumulate. If defined, the values of RENDER_MAX_TIME_MS, RENDER_MIN_SAMPLES, and RENDER_MAX_SAMPLES will all be ignored.

RENDER_PROGRESSIVE

If enabled, the window will alternate between draw and present passes, so the current state of the rendering is always visible. If disabled, the window will appear black until the accumulation phase is complete, as required by Revision rules.

CAPTURE_SAVE_PNG

In Capture mode, the render will be saved as a PNG.

CAPTURE_SAVE_JPG

In Capture mode, the render will be saved as a JPG.

CAPTURE_SAVE_U8_BIN

In Capture mode, the render will be saved as a binary file containing 8-bit-per-channel RGB triplets.

CAPTURE_SAVE_F32_BIN

In Capture mode, the render will be saved as a binary file containing float32 RGBA data.

DESPERATE

If enabled, uses a couple of risky tricks to shave a few bytes.

REVISION_RULESET

If enabled, sets up a party-safe configuration based on the Revision rules.

Special Thanks

• LLB, for Shader Minifier
• Blueberry & Mentor, for Crinkler
• noby, for Leviathan, which served as an invaluable reference.