# Python How To¶

Often you just need a "pointer" to an example that shows you how to do something.

Here are some snippets and examples that highlight interesting features that may help you:

## Callback¶

CallBack Setting up a callback with client data. Two different methods are demonstrated.

## Camera¶

CameraModel1 Illustrate camera movement around the focal point.
CameraModel2 camera movement centered at the camera position.
CameraPosition Get the camera position while moving the image.
ShareCamera Use the same camera for all renderers.

## Coloring¶

ShareCamera Store background colors in a vector for later extraction of the red, green and blue components.

## Glyphing¶

InteractorStyleTrackballCamera Here points are represented as glyphs.
PointToGlyph How to represent points as glyphs.

## Image¶

WriteImage Write out an image of various types.

## Polydata¶

ReadPolyData This snippet works for most PolyData.

## Random¶

If you want to ensure that the same random points/colors are used in C++ and other languages then it is best to use vtkMinimalStandardRandomSequence.

HighlightWithSilhouette Here we use randomly positioned spheres with random colors. A vtkLookupTable is filled with random colors.

## Render Windows¶

Model Multiple render windows.

## Searching for relevant examples?¶

SelectExamples Given a VTK Class and a language, select the matching examples.

## StructuredDataset¶

How to visualise the information in a structured dataset. All these examples use the combustor dataset.

CombustorIsosurface Generate an isosurface of constant flow density.
CutStructuredGrid Cut through structured grid with plane. The cut plane is shown solid shaded. A computational plane of constant k value is shown in wireframe for comparison. The colors correspond to flow density. Cutting surfaces are not necessarily planes: implicit functions such as spheres, cylinders, and quadrics can also be used.
ProbeCombustor Probing data in a combustor. Probes are regular arrays of 50 by 50 points that are then passed through a contouring filter.
PseudoVolumeRendering Here we use 100 cut planes, each with an opacity of 0.05. They are then rendered back-to-front to simulate volume rendering.
Rainbow Using different vtkLookupTables.
StreamLines Seed streamlines with vectors from a structured grid.
StreamlinesWithLineWidget Interact with the streamlines in the combustor dataset.
VelocityProfile Warping the geometry of three planes to show flow momentum.
WarpCombustor Carpet plots of combustor flow energy in a structured grid. Colors and plane displacement represent energy values.

## Transforms¶

Frog This code uses a general way of specifying transformations that can permute image and other geometric data in order to maintain proper orientation regardless of the acquisition order. See the class SliceOrder.