bottom-to-top oriented gitgraphs to mimic git logs

[arkadianriver]

Proposal

First, I love how beautiful Mermaid's git graphs are compared to others!

This proposal is to add BT orientation, because that's how we commonly see git graphs in the wild when viewing git log histories (with commits listed in reverse chronological order).

Use Cases

This is particularly useful when working with folks and documenting situations that they might see in their git histories. It would be helpful to keep the orientation the same.

Screenshots

Two such examples of this orientation are the git histories provided by the VS Code extensions Git Graph and GitLens:

• GitGraph:
  

• GitLens:
  

Syntax

BT to go along with the existing LR and TB

Implementation

This is a proposal which I'd love to see built into mermaid by the wonderful community.

[JingyuMarcelLee]

For now, I simply flipped the TB orientation. The syntax is exactly the same with the TB option except you add BT after gitgraph in the markdown. Below are the same gitgraph, but with different orientations.

• TB

    ---
    title: Three branches and a cherry-pick from each (top-to-bottom)
    ---
    gitGraph TB:
    commit id: "ZERO"
    branch develop
    commit id:"A"
    checkout main
    commit id:"ONE"
    checkout develop
    commit id:"B"
    branch featureA
    commit id:"FIX"
    commit id: "FIX-2"
    checkout main
    commit id:"TWO"
    cherry-pick id:"A"
    commit id:"THREE"
    cherry-pick id:"FIX"
    checkout develop
    commit id:"C"
    merge featureA

• BT

    ---
    title: Three branches and a cherry-pick from each (bottom-to-top)
    ---
    gitGraph BT:
    commit id: "ZERO"
    branch develop
    commit id:"A"
    checkout main
    commit id:"ONE"
    checkout develop
    commit id:"B"
    branch featureA
    commit id:"FIX"
    commit id: "FIX-2"
    checkout main
    commit id:"TWO"
    cherry-pick id:"A"
    commit id:"THREE"
    cherry-pick id:"FIX"
    checkout develop
    commit id:"C"
    merge featureA

Please let me know if there should be any additional changes.

[arkadianriver]

Nice, thanks for working on this Jingyu. 😎