EXT_polygon_offset_clamp: polygonOffsetClampEXT() method
The polygonOffsetClampEXT() method of the EXT_polygon_offset_clamp extension of the WebGL API specifies the scale factor and units used to calculate depth offsets, like WebGLRenderingContext.polygonOffset(), and a limit for the resulting offset.
The offset is computed from factor and units in the same way as with polygonOffset(), then limited by clamp:
- If
clampis positive, the offset is at mostclamp. - If
clampis negative, the offset is at leastclamp. - If
clampis0orNaN, the offset isn't limited.
Calling polygonOffset() is the same as calling polygonOffsetClampEXT() with a clamp of 0, so it removes the limit.
The depth offset applies only when gl.POLYGON_OFFSET_FILL is enabled with WebGLRenderingContext.enable().
Syntax
polygonOffsetClampEXT(factor, units, clamp)
Parameters
factor-
A
GLfloatwhich sets the scale factor for the variable depth offset for each polygon. The default value is 0. units-
A
GLfloatwhich sets the multiplier by which an implementation-specific value is multiplied with to create a constant depth offset. The default value is 0. clamp-
A
GLfloatwhich sets the maximum (if positive) or minimum (if negative) depth offset. The default value is 0, which means no limit.
Return value
None (undefined).
Examples
Limiting the depth offset
This example enables the depth offset, sets a factor of 2 and units of 3, and limits the offset to 0.001:
const ext = gl.getExtension("EXT_polygon_offset_clamp");
gl.enable(gl.POLYGON_OFFSET_FILL);
ext.polygonOffsetClampEXT(2, 3, 0.001);
To check the current values, query the POLYGON_OFFSET_FACTOR, POLYGON_OFFSET_UNITS, and POLYGON_OFFSET_CLAMP_EXT constants:
gl.getParameter(gl.POLYGON_OFFSET_FACTOR); // 2
gl.getParameter(gl.POLYGON_OFFSET_UNITS); // 3
gl.getParameter(ext.POLYGON_OFFSET_CLAMP_EXT); // 0.0010000000474974513
Specifications
| Specification |
|---|
| WebGL EXT_polygon_offset_clamp Extension Specification |