Perspective Volume Chart

Vvidget Code > Dictionary > Perspective Volume Chart

This section explains how to form a dictionary for a Perspective Volume Chart such as this:

Rectilinear Perspective Volume Chart

A perspective volume chart is a sequence of transformed scalars positioned on a regular 3D grid. Those scalars are mapped to a color using a color mapping. The specifics are determined by the template configuration which is a Vvidget Builder document. The Vvidget Builder manual explains those issues in more detail. If the color mapping coefficients are opaque then the volume appears solid. If it contains a transparent component then you can see into the volume and perhaps the volume will appear complex especially if the color map is setup correctly to make certain regions transparent and others opaque.

For more data exploration and layout the graph can be exported to Vvidget Builder where it can be rotated in realtime.

An example code fragment illustration follows:


/* Start of Illustration Code Fragment */



[constructor VC_append_key:"chart_type" string_value:@"perspective volume"];

[constructor VC_append_key:"chart_subtype" string_value:@"linear"];

[constructor VC_append_key:"chart_format_type" string_value:@"default"];

[constructor VC_append_key:"title" string_value:@"My Title"];

[constructor VC_append_key:"x_title" string_value:@"My X Title"];

[constructor VC_append_key:"y_title" string_value:@"My Y Title"];

[constructor VC_append_key:"z_title" string_value:@"My Z Title"];

[constructor VC_append_key:"grid_x_length" string_value:@"2"];

[constructor VC_append_key:"grid_x_minimum" string_value:@"1.0"];

[constructor VC_append_key:"grid_x_maximum" string_value:@"3.0"];

[constructor VC_append_key:"grid_y_length" string_value:@"2"];

[constructor VC_append_key:"grid_y_minimum" string_value:@"1.0"];

[constructor VC_append_key:"grid_y_maximum" string_value:@"3.0"];

[constructor VC_append_key:"grid_z_length" string_value:@"2"];

[constructor VC_append_key:"grid_z_minimum" string_value:@"1.0"];

[constructor VC_append_key:"grid_z_maximum" string_value:@"3.0"];

[constructor VC_append_key:"color_map_1_type" string_value:@"1"];

[constructor VC_append_key:"color_map_2_type" string_value:@"1"];

[constructor VC_append_key:"color_map_1_length" string_value:@"32"];

[constructor VC_append_key:"color_map_2_length" string_value:@"32"];

[constructor VC_append_key:"color_map_rgb_11" string_value:@"FF0000FF"];

[constructor VC_append_key:"color_map_rgb_12" string_value:@"FFFFFFFF"];

[constructor VC_append_key:"color_map_rgb_21" string_value:@"FFFFFFFF"];

[constructor VC_append_key:"color_map_rgb_22" string_value:@"0000FFFF"];

[constructor VC_append_key:"data_values" string_value:@"0.0 0.2 0.3 0.4 0.5 0.6 0.7 0.1"];



/* End of Illustration Code Fragment */

The code fragment above can be inserted into the illustration code section of the Illustration project for an immediate running Cocoa application. For additional information consult the Illustration section.

The following table defines the input string key and value pairs:

Chart Specific Entries
Key	Value Description
chart_type¹	The string perspective volume, indicating a Perspective Volume Chart.
chart_subtype¹	The string linear.
chart_format_type¹	The string default.
title	The main title of the graph. If this key is not present then the template's title is used.
x_title	The x title of the graph. If this key is not present then the template's x-title is used.
y_title	The y title of the graph. If this key is not present then the template's y-title is used.
z_title	The z title of the graph. If this key is not present then the template's z-title is used.
grid_x_length	The number of grid cells in the x-direction.
grid_x_minimum	The minimum x-value of the grid.
grid_x_maximum	The maximum x-value of the grid.
grid_y_length	The number of grid cells in the y-direction.
grid_y_minimum	The minimum y-value of the grid.
grid_y_maximum	The maximum y-value of the grid.
grid_z_length	The number of grid cells in the z-direction.
grid_z_minimum	The minimum z-value of the grid.
grid_z_maximum	The maximum z-value of the grid.
color_map_1_type	The color mapping type (0, 1, 2, 3).
color_map_1_length	Number of colors in map 1.
color_map_rgb_11	Beginning color of the color mapping.
color_map_rgb_12	Ending color of the color mapping.
color_map_2_type	The color mapping type (0, 1, 2, 3).
color_map_2_length	Number of colors in map 2.
color_map_rgb_21	Beginning color of the color mapping.
color_map_rgb_22	Ending color of the color mapping.
templates	A custom Templates directory.
data_values	A white space delimited list of values representing the density-values of the grid matrix. A density value is a value between zero and one inclusive. See Data Oriented keys for additional information and keys.

¹ Do not include this key value pair in the Interface Builder Plugin Inspector input string. It is included for you automatically.

If you incorporate this functionality into your own application then please consult Cocoa Programming. If you incorporate this functionality into CLI scripts then please consult Script Programming.

You can also modify the following Templates:

Template Document Names
Template	Description
PVST_Perspective_Volume_Chart	Forms the static attributes for the chart.

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