Description

This sample demonstrates using the NV_path_rendering OpenGL extension to draw text arranged like spokes in a wheel, with a slight 3D projection applied to the rendering.

Screenshot

APIs Used

  • NV_path_rendering
  • EXT_direct_state_access

Shared User Interface

The Graphics samples all share a common app framework and certain user interface elements, centered around the "Tweakbar" panel on the left side of the screen which lets you interactively control certain variables in each sample.

To show and hide the Tweakbar, simply click or touch the triangular button positioned in the top-left of the view.

Technical Details

This sample demonstrates NV_path_rendering drawing spinning text with a slight projection applied to the text arranged in a spinning wheel. The shading of the text uses a smooth color gradient generated with glPathColorGenNV.

The glyphs for the text on the spinning wheel are created with the glPathGlyphRangeNV command.

The text spacing with kerning is determined with the glGetPathSpacingNV query.

The instanced path APIs are used to efficiently draw the filled and stroked text:

  • glStencilFillPathInstancedNV
  • glCoverFillPathInstancedNV
  • glStencilStrokePathInstancedNV
  • glCoverStrokePathInstancedNV