# Step 7 A 2D triangle

## OpenGL default coordinate system

<figure><img src="https://3464970502-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F3JUKGJZ67JX02QZdPhsy%2Fuploads%2FFOZrFX0SUSTlwVOilA9Z%2Fimage.png?alt=media&#x26;token=6503865d-b1b8-4c88-95d8-3729f0556198" alt=""><figcaption></figcaption></figure>

## Triangle data

We like to draw a 2D triangle like the following

<figure><img src="https://3464970502-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F3JUKGJZ67JX02QZdPhsy%2Fuploads%2Fv162uTjJ4og5gQPKJngR%2Fae9b377b-8b3d-4f2b-8871-7e6b55a59fd5.png?alt=media&#x26;token=74438f09-0e94-4ce9-9c99-ed970aa6915a" alt=""><figcaption></figcaption></figure>

The three vertices of the has coordinates of （-1, -1),  (1, -1), (0, 1) in counterclockwise order.

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