feat: Add File header G-code option and print_time_sec/filament_length_m placeholders #870

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MrUnknownDE · 2026-04-05T16:33:40+02:00

MrUnknownDE commented

2026-04-05 16:33:40 +02:00

Originally created by @davydmaker on 2/5/2026

Problem

Some Creality printers (e.g. Ender-3 V3 SE) rely on metadata comments in the first lines of G-code files to display print info on the screen (estimated time, filament usage, layer height). This follows a format originally used by Cura/Creality Print:

;FLAVOR:Marlin
;TIME:3708.97
;Filament used:6.21m
;Layer height:0.2

OrcaSlicer currently has no way to write content before the HEADER_BLOCK in the G-code output, and does not expose print_time_sec or filament_length_m as usable placeholders. As a result, these printers show zeroed-out print info on screen.

Changes

1. New placeholders (post-processing)

Added two new G-code placeholders resolved during post-processing:

{print_time_sec} — total estimated print time in seconds (double)
{filament_length_m} — total filament length in meters (double)

These values are only available after G-code generation, so they use inline marker replacement (@PRINT_TIME_SEC@, @FILAMENT_LENGTH_M@) that GCodeProcessor::run_post_process() substitutes with actual computed values — the same pattern used by existing M73 and layer count placeholders.

2. New "File header G-code" option (`machine_top_gcode`)

Added a new G-code field in Printer Settings > Machine G-code that writes content at the very top of the output file, before HEADER_BLOCK_START. This allows users to add firmware-specific metadata that must appear in the first lines.

3. Creality Ender-3 V3 SE profile update

Pre-configured the Ender-3 V3 SE profiles (all 4 nozzle variants) with a default machine_top_gcode value matching the Cura-compatible header format, so print info displays correctly out of the box.

Screenshots

Before (current OrcaSlicer)	After (this PR)

Tests

Sliced test model with Ender-3 V3 SE profile
Verified G-code output contains correct values in first lines:
- ;TIME: with actual print time in seconds
- ;Filament used: with filament length in meters
- ;Layer height: with correct layer height
Verified {print_time_sec} and {filament_length_m} work in both Machine Start G-code and File header G-code fields
Verified empty machine_top_gcode produces no extra output
Built and tested on macOS (arm64)

*Originally created by @davydmaker on 2/5/2026* ## Problem Some Creality printers (e.g. Ender-3 V3 SE) rely on metadata comments in the first lines of G-code files to display print info on the screen (estimated time, filament usage, layer height). This follows a format originally used by Cura/Creality Print: ``` ;FLAVOR:Marlin ;TIME:3708.97 ;Filament used:6.21m ;Layer height:0.2 ``` OrcaSlicer currently has no way to write content before the `HEADER_BLOCK` in the G-code output, and does not expose `print_time_sec` or `filament_length_m` as usable placeholders. As a result, these printers show zeroed-out print info on screen. ## Changes ### 1. New placeholders (post-processing) Added two new G-code placeholders resolved during post-processing: - `{print_time_sec}` — total estimated print time in seconds (double) - `{filament_length_m}` — total filament length in meters (double) These values are only available after G-code generation, so they use inline marker replacement (`@PRINT_TIME_SEC@`, `@FILAMENT_LENGTH_M@`) that `GCodeProcessor::run_post_process()` substitutes with actual computed values — the same pattern used by existing M73 and layer count placeholders. ### 2. New "File header G-code" option (`machine_top_gcode`) Added a new G-code field in **Printer Settings > Machine G-code** that writes content at the very top of the output file, before `HEADER_BLOCK_START`. This allows users to add firmware-specific metadata that must appear in the first lines. ### 3. Creality Ender-3 V3 SE profile update Pre-configured the Ender-3 V3 SE profiles (all 4 nozzle variants) with a default `machine_top_gcode` value matching the Cura-compatible header format, so print info displays correctly out of the box. # Screenshots | Before (current OrcaSlicer) | After (this PR) | |---|---| | ![IMG_5285](https://github.com/user-attachments/assets/fdd2cc96-6593-4108-83f4-e272d5547467) | ![IMG_5286](https://github.com/user-attachments/assets/6cb4091a-4560-4596-93d9-49f2ff8f0a2b) | ## Tests - Sliced test model with Ender-3 V3 SE profile - Verified G-code output contains correct values in first lines: - `;TIME:` with actual print time in seconds - `;Filament used:` with filament length in meters - `;Layer height:` with correct layer height - Verified `{print_time_sec}` and `{filament_length_m}` work in both Machine Start G-code and File header G-code fields - Verified empty `machine_top_gcode` produces no extra output - Built and tested on macOS (arm64)

MrUnknownDE closed this issue

2026-04-05 16:33:40 +02:00

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Reference: github/OrcaSlicer#870

feat: Add File header G-code option and print_time_sec/filament_length_m placeholders #870