Mesh Gradients - Revision history

Jona: /* Corner Operations */

2020-10-08T12:07:46Z

Corner Operations

← Older revision		Revision as of 12:07, 8 October 2020
Line 73:		Line 73:
	;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful and is probably not so useful now there is bicubic smoothing.		;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful and is probably not so useful now there is bicubic smoothing.

	;~~SHIT~~-I: Subdivide mesh between two selected nodes		;Shift-I: Subdivide mesh between two selected nodes

	== Smoothing ==		== Smoothing ==

Adambelis: /* Corner Operations */

2020-10-07T16:11:34Z

Corner Operations

← Older revision		Revision as of 16:11, 7 October 2020
Line 73:		Line 73:
	;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful and is probably not so useful now there is bicubic smoothing.		;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful and is probably not so useful now there is bicubic smoothing.

			;SHIT-I: Subdivide mesh between two selected nodes

	== Smoothing ==		== Smoothing ==

Tavmjong: /* Edit */

2017-01-03T19:39:12Z

Edit

← Older revision		Revision as of 19:39, 3 January 2017
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	* Single click on path to select end nodes (with Shift, add to selection, with Ctrl, toggle selection). This is quite useful to select nodes hidden by other nodes (as with conical gradients).		* Single click on path to select end nodes (with Shift, add to selection, with Ctrl, toggle selection). This is quite useful to select nodes hidden by other nodes (as with conical gradients).
	* Double click on path to divide row/column by two at that point (there is no reverse operation yet).		* Double click on path to divide row/column by two at that point (there is no reverse operation yet).
	* Undo should work in trunk ~~an latest~~ 0.92.x.		* Undo should work in trunk and 0.92.
	* Meshes do not resize automatically when a shape is resized. Meshes can be resized to the bounding box of a shape using the resize button in the Mesh-tool tool-bar (geometric box for fill, visual box for stroke).		* Meshes do not resize automatically when a shape is resized. Meshes can be resized to the bounding box of a shape using the resize button in the Mesh-tool tool-bar (geometric box for fill, visual box for stroke).

Moini: /* Edit */ add box selection info

2017-01-03T15:44:13Z

Edit: add box selection info

← Older revision		Revision as of 15:44, 3 January 2017
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	** Circle: Bezier handles		** Circle: Bezier handles
	** Square: Tensor handles (see below on how to enable/disable).		** Square: Tensor handles (see below on how to enable/disable).
	* Click on node to select or deselect node (with Shift, add/remove from selection).		* Click on node to select or deselect node (with Shift, add/remove from selection). With mesh tool, you can also box-select multiple nodes.
	* Single click on path to select end nodes (with Shift, add to selection, with Ctrl, toggle selection). This is quite useful to select nodes hidden by other nodes (as with conical gradients).		* Single click on path to select end nodes (with Shift, add to selection, with Ctrl, toggle selection). This is quite useful to select nodes hidden by other nodes (as with conical gradients).
	* Double click on path to divide row/column by two at that point (there is no reverse operation yet).		* Double click on path to divide row/column by two at that point (there is no reverse operation yet).

Moini: /* Enable */ Update for 0.92

2017-01-03T15:33:12Z

Enable: Update for 0.92

← Older revision		Revision as of 15:33, 3 January 2017
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	== Enable ==		== Enable ==

	* Use a build compiled with CPPFLAGS="-DWITH_MESH"		This feature is available by default from Inkscape 0.92 on.

	Or		For version 0.48.5, you need to either:

	* ~~Enable~~ by adding Alt-M shortcut to inkscape/keys/default.xml (Preferences->Interface->Keyboard Shortcuts, search for 'mesh', add, save, replace old file with saved file).		* build compiled with CPPFLAGS="-DWITH_MESH" or

			* enable the hidden feature by adding Alt-M (or any other available) shortcut to inkscape/keys/default.xml (Preferences->Interface->Keyboard Shortcuts, search for 'mesh', add, save, replace old file with saved file).

	== Videos ==		== Videos ==

Tavmjong: /* Enable */

2016-11-23T12:08:12Z

Enable

← Older revision		Revision as of 12:08, 23 November 2016
Line 10:		Line 10:
	== Enable ==		== Enable ==

	* Use a ~~development~~ build compiled with CPPFLAGS="-DWITH_MESH"		* Use a build compiled with CPPFLAGS="-DWITH_MESH"

	Or		Or

Tavmjong: /* Edit */

2016-11-23T12:07:21Z

Edit

← Older revision		Revision as of 12:07, 23 November 2016
Line 49:		Line 49:
	** Circle: Bezier handles		** Circle: Bezier handles
	** Square: Tensor handles (see below on how to enable/disable).		** Square: Tensor handles (see below on how to enable/disable).
			* Click on node to select or deselect node (with Shift, add/remove from selection).
			* Single click on path to select end nodes (with Shift, add to selection, with Ctrl, toggle selection). This is quite useful to select nodes hidden by other nodes (as with conical gradients).
	* Double click on path to divide row/column by two at that point (there is no reverse operation yet).		* Double click on path to divide row/column by two at that point (there is no reverse operation yet).
	* Undo should work in trunk an latest 0.92.x.		* Undo should work in trunk an latest 0.92.x.

Tavmjong: /* Smoothing */

2016-11-08T14:31:03Z

Smoothing

← Older revision		Revision as of 14:31, 8 November 2016
Line 78:		Line 78:

	Smoothing is implemented currently in Inkscape by splitting each 'normal' patch into an eight by eight array of patches where the corner nodes of each sub-patch are set using interpolation and then rendering the sub-patches with normal mesh patches. There is some evidence that this is how smoothing is implemented in Illustrator and CorelDraw.		Smoothing is implemented currently in Inkscape by splitting each 'normal' patch into an eight by eight array of patches where the corner nodes of each sub-patch are set using interpolation and then rendering the sub-patches with normal mesh patches. There is some evidence that this is how smoothing is implemented in Illustrator and CorelDraw.

			== Syntax ==

			The SVG 2 mesh syntax has evolved:

			*<meshGradient> → <mesh> → <meshgradient>
			*<meshRow> → <meshrow>
			*<meshPatch> → <meshpatch>

			The main change was made to avoid using CamelCase which would require browsers to manually adjust their parsers (which are normally case insensitive). <mesh> was changed to <meshgradient> in order that <mesh> can be used for a shape that automatically generates a path that takes the shape of the mesh gradient outline. The latest 0.92.x and trunk should be able to read meshes generated with older syntax. One can also manually update drawings by editing them in a plain text editor.

Tavmjong at 14:08, 8 November 2016

2016-11-08T14:08:15Z

← Older revision		Revision as of 14:08, 8 November 2016
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	This page documents Inkscape's ~~experimental~~ implementation of SVG 2 mesh gradients. Please don't hesitate to improve this page (or even the mesh code!).		This page documents Inkscape's implementation of SVG 2 mesh gradients. Please don't hesitate to improve this page (or even the mesh code!).


	'''WARNING: Mesh SVG syntax is subject to change.'''		'''WARNING: Mesh SVG syntax is subject to change. Mesh support in browsers is not certain'''

			For web use, one can replace a mesh by a bitmap using Edit->Create bitmap copy. For print, export to PDF supports meshes.

			Undo should now work in trunk and the latest 0.92.x builds.

	== Enable ==		== Enable ==
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	To create a mesh:		To create a mesh:

			Either:
	# Change to Mesh tool.		# Change to Mesh tool.
	# Select mesh type (normal, conical).		# Select mesh type (normal, conical).
Line 27:		Line 32:
	# Select object to add mesh.		# Select object to add mesh.
	# Click-drag inside object.		# Click-drag inside object.

			Or:
			# Select object to add mesh.
			# Select mesh icon in Fill and Stroke dialog (Fill or Stroke tab).
			#* If an object does not have a mesh fill, a new default mesh will be created using the stored values from the Mesh-tool tool-bar.
			#* Choose pre-existing mesh from drop-down menu.

			== Choose ==

			One can reuse an existing mesh via selecting a mesh from the drop-down menu in the Fill and Stroke dialog when the mesh icon is selected. The mesh will be sized to the bounding box of the object (geometric box for fill, visual box for stroke). Note: A copy of the mesh is created.

	== Edit ==		== Edit ==
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	** Square: Tensor handles (see below on how to enable/disable).		** Square: Tensor handles (see below on how to enable/disable).
	* Double click on path to divide row/column by two at that point (there is no reverse operation yet).		* Double click on path to divide row/column by two at that point (there is no reverse operation yet).
	* Undo not ~~fully implemented~~.		* Undo should work in trunk an latest 0.92.x.
			* Meshes do not resize automatically when a shape is resized. Meshes can be resized to the bounding box of a shape using the resize button in the Mesh-tool tool-bar (geometric box for fill, visual box for stroke).

	== Corner Operations ==		== Corner Operations ==
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	;Ctrl-A: Select all corner nodes.		;Ctrl-A: Select all corner nodes.

	;Alt-B: Toggle selected patch sides between linear and curve. (Select both corner nodes of side to select side.)		;Alt-B: Toggle selected patch sides between linear and curve. (Select both corner nodes of side to select side.) (Also available via button in menu bar.)

			;Alt-C: Attempt to convert selected sides into elliptical arcs by changing the length of the Bezier handles. (Also available via button in menu bar.)

			;Alt-K: Sample colors underneath mesh at corner nodes. For nodes at edge of mesh, move sample point inside mesh. (Also available via button in menu bar. Useful for vectorizing a photo.)

	~~;Alt-C~~: ~~Attempt to convert selected sides into elliptical arcs by changing the length of the Bezier handles.~~		Experimental features:

	;Alt-G: Toggle on/off tensor points for selected patches. (Select all four corner nodes of a patch to select patch.)		;Alt-G: Toggle on/off tensor points for selected patches. (Select all four corner nodes of a patch to select patch.) Tensor points are not part of SVG 2 meshes.

	;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful.		;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful and is probably not so useful now there is bicubic smoothing.

	~~;Alt-K: Sample colors underneath mesh at corner nodes. For nodes at edge of mesh, move sample point inside mesh. (Useful for vectorizing a photo.)~~

	== Smoothing ==		== Smoothing ==
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	Coons Mesh Patches use bilinear interpolation for the color profile. This leads to abrupt changes in the derivatives of the colors at patch boundaries which the human eye is very sensitive (see [https://en.wikipedia.org/wiki/Mach_bands Mach Banding]).		Coons Mesh Patches use bilinear interpolation for the color profile. This leads to abrupt changes in the derivatives of the colors at patch boundaries which the human eye is very sensitive (see [https://en.wikipedia.org/wiki/Mach_bands Mach Banding]).

	~~Experimental smoothing is included in trunk. Smoothing is not part of~~ the ~~SVG 2 standard (yet). Two different types of~~ smoothing ~~are implemented:~~		To smooth the boundaries, select "Bicubic" smoothing. This uses
			[https://en.wikipedia.org/wiki/Bicubic_interpolation Bicubic Interpolation].
	* [https://en.wikipedia.~~org/wiki/Cubic_Hermite_spline Cubic Hermite Splines]~~
	* [https://en.wikipedia.org/wiki/Bicubic_interpolation Bicubic Interpolation]

	~~Cubic Hermite splines does the interpolation in one direction at a time. Bicubic interpolation does the interpolation in both directions at the same time adding in cross-derivative terms.~~

	Smoothing is implemented by splitting each 'normal' patch into an eight by eight array of patches where the corner nodes of each sub-patch are set using interpolation and then rendering the sub-patches with normal mesh patches. There is some evidence that this is how smoothing is implemented in Illustrator.


	~~Smoothing type:~~

	* None
	* Default: Same as Smooth7.
	* Cubic Hermite Splines
	** Smooth1: Derivatives zero at patch boundaries.
	** Smooth2: Catmul-Rom calculation of derivatives. Along edge double first/last point.
	** Smooth3: Catmul-Rom calculation of derivatives. Along edge reflect around first/last point.
	** Smooth4: Catmul-Rom calculation of derivatives. Parabolic profile for edge patches.
	** Smooth5: Same as Smooth4 but attempt to ensure local minima/maxima remain on patch boundaries.
	* Bicubic interpolation
	** Smooth6: Catmul-Rom calculation of derivatives. Along edge reflect around first/last point.
	** Smooth7: Catmul-Rom calculation of derivatives. Parabolic profile for edge patches. Attemtp to ensure local minima/maxima remain on patch boundaries.

	~~Next step~~ is ~~to replace Catmul~~-~~Rom derivative calculations by finite difference methods~~.		Smoothing is implemented currently in Inkscape by splitting each 'normal' patch into an eight by eight array of patches where the corner nodes of each sub-patch are set using interpolation and then rendering the sub-patches with normal mesh patches. There is some evidence that this is how smoothing is implemented in Illustrator and CorelDraw.

Tavmjong: /* Corner Operations */

2015-02-02T15:38:03Z

Corner Operations

← Older revision		Revision as of 15:38, 2 February 2015
Line 41:		Line 41:
	;Ctrl-A: Select all corner nodes.		;Ctrl-A: Select all corner nodes.

	;~~Ctrl~~-B: Toggle selected patch sides between linear and curve. (Select both corner nodes of side to select side.)		;Alt-B: Toggle selected patch sides between linear and curve. (Select both corner nodes of side to select side.)

	;~~Ctrl~~-C: Attempt to convert selected sides into elliptical arcs by changing the length of the Bezier handles.		;Alt-C: Attempt to convert selected sides into elliptical arcs by changing the length of the Bezier handles.

	;~~Ctrl~~-G: Toggle on/off tensor points for selected patches. (Select all four corner nodes of a patch to select patch.)		;Alt-G: Toggle on/off tensor points for selected patches. (Select all four corner nodes of a patch to select patch.)

	;~~Ctrl~~-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful.		;Alt-J: Attempt to smooth color transition around a corner by changing length of Bezier handles. This needs lots of work to make it truly useful.

	;~~Ctrl~~-K: Sample colors underneath mesh at corner nodes. For nodes at edge of mesh, move sample point inside mesh.		;Alt-K: Sample colors underneath mesh at corner nodes. For nodes at edge of mesh, move sample point inside mesh. (Useful for vectorizing a photo.)

	== Smoothing ==		== Smoothing ==