C

WebGLSupport

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Class containing helper methods for WebGL rendering.
Inheritance Hierarchy

Remarks

Specifically, this class helps in creating, caching and using webgl programs that should work with the yFiles coordinate systems. Instances of this class can be obtained from the webGLSupport property of the context that is passed to render and render.

This class cannot be instantiated

Members

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Methods

deleteProgram

(program: WebGLProgram)
Can be called to deallocate and delete program resources created previously via useProgram.
WebGL resources are automatically freed when the respective JavaScript objects are garbage collected. So there is no need to call this method explicitly. However, this method allows authors to delete a program early. This method will also perform the actual call to gl.deleteProgram().
final

Parameters

program: WebGLProgram
A program created by useProgram

Throws

Exception ({ name: 'InvalidOperationError' })
If this method is invoked outside of createVisual or updateVisual. When not currently rendering, this method cannot be used. For instance, this method cannot be used inside a dispose callback.

useProgram

(vertexShaderSource: string, fragmentShaderSource: string): WebGLProgram
Sets the active program as defined by the vertex and fragment shader sources and provides view and world transforms that can be used in the shader definitions.

The following transforms are made available to the shader:

  • u_yf_worldToWebGL – A uniform of type mat3 that defines the 2D view transform . Apply this transform to world coordinates to render in the WebGL coordinate system.
  • u_yf_worldToWebGL_3d – A uniform of type mat4 that defines the 3D view transform . Apply this transform to world coordinates to render in the WebGL coordinate system.
  • u_yf_worldToIntermediate – A uniform of type mat3 that defines the 2D intermediate transform . Apply this transform to world coordinates to render in the intermediate coordinate system which incorporates viewport position and zoom.
  • u_yf_intermediateToView – A uniform of type mat3 that defines the 2D projection transform . Apply this transform to intermediate coordinates to render in the view coordinate system. Note that this does not include normalizing the coordinates into WebGL's coordinate system.
  • u_yf_viewToWebGL – A uniform of type mat3 that transforms 2D coordinates from the view coordinate system into the WebGL coordinate system.
  • u_yf_viewToWebGL_3d – A uniform of type mat4 that transforms 3D coordinates from the view coordinate system into the WebGL coordinate system.
  • u_yf_intermediateToWebGL – A uniform of type mat3 that transforms 2D coordinates from the intermediate coordinate system into the WebGL coordinate system.
  • u_yf_intermediateToWebGL_3d – A uniform of type mat4 that transforms 3D coordinates from the intermediate coordinate system into the WebGL coordinate system.
  • u_yf_zoom – A uniform of type float that contains the current zoom factor, but does not take into account the device pixel ratio.
  • u_yf_devicePixelRatio – A uniform of type float that contains the current device pixel ratio
  • u_yf_pixelsPerUnit – A uniform of type float that contains the current number of screen pixels for each unit in the world coordinate system. It's the product of zoom factor and device pixel ratio and should be preferred over u_yf_zoom * u_yf_devicePixelRatio to keep the number of uniforms low.

Note that the 3d transforms clip z-values smaller that 0 or greater than 1000.

final

Parameters

vertexShaderSource: string
The vertex shader source text.
fragmentShaderSource: string
The fragment shader source text.

Return Value

WebGLProgram
A new or cached instance of WebGLProgram.

Throws

Exception ({ name: 'InvalidOperationError' })
If this method is invoked outside of createVisual or updateVisual. When not currently rendering, this method cannot be used.

Examples

Example vertex shader using 2D coordinates:
attribute vec2 position;
void main() {
  gl_position = vec4((u_yf_worldToWebGL * vec3(position, 1)).xy, 0, 1);
}
Example vertex shader using 3D coordinates:
attribute vec3 position;
void main() {
  gl_Position = u_yf_worldToWebGL_3d * vec4(position, 1);
}

See Also

API
deleteProgram

Events

'flushing-context'

: EventArgs
Occurs when all visuals have finished rendering into the current WebGL rendering context.
This event can be registered to during rendering to the current WebGL context. It is raised when all other visuals in the same context have finished rendering. This event is raised only once for each context and all listeners are automatically removed after the event is fired. This allows for running cleanup and special GL effects at the end of batched GL operations.

Properties of

EventArgs