Perspective Surface Chart

Vvidget Code > Dictionary > Perspective Surface Chart

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

Rectilinear Perspective Surface Chart

A perspective surface chart is a sequence of transformed scalars positioned on a regular x-y grid and given z-values that are the value of those scalars. Then those values are used to interpolate a surface over the regular grid. Finally, a color can be applied to the surface to represent a different dimension. The specifics are determined by the template configuration which is a Vvidget Builder document. The Vvidget Builder manual explains those issues in more detail.

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 surface"];

[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:@"5"];

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

[constructor VC_append_key:"grid_x_maximum" string_value:@"5.0"];

[constructor VC_append_key:"grid_y_length" string_value:@"5"];

[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:"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:@"1.0 2.0 3.0 4.0 5.0 1.1 2.1 3.1 4.1 5.1 1.2 2.2 3.8 4.2 5.2 1.3 2.3 3.3 4.3 5.3 1.4 2.4 3.4 4.4 5.0"];



/* 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 dictionary key and value pairs:

Chart Specific Entries
Key	Value Description
chart_type¹	The string perspective surface, indicating a Perspective Surface 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.
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 z-values of the grid matrix. 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_Surface_Chart	Forms the static attributes for the chart.

Grid Definition

The value for the key data_values is a list of numbers (a string representation) each number delimited by a blank which is mapped onto a regular grid in the normal way in an x-contiguous fashion. That is, lets say there are "n" z-values:

z₁ z₂ z₃ ... z_n

On a grid with definitions and relationships:

n_x The number of z-values in the x-direction (the value of the key grid_x_length)

n_y The number of z-values in the y-direction (the value of the key grid_y_length)

n Must equal n_x n_y

x_min The value of the key grid_x_minimum

x_max The value of the key grid_x_maximum

y_min The value of the key grid_y_minimum

y_max The value of the key grid_y_maximum

Δx = (x_max - x_min)/(n_x - 1)

Δy = (y_max - y_min)/(n_y - 1)

i The index of the i-th element in the list of z-values (starting at 1)

j The index of the j-th z-value in the x-direction (starting at 1)

k The index of the k-th z-value in the y-direction (starting at 1)

i = (k-1) n_y + j

then for the z-value z_j,k (which is z_i = z_{(k-1) n_y + j}) the x and y values are defined as:

x_j = x_min + Δx (j - 1)

y_k = y_min + Δy (k - 1)

to form the triplet (3D point): {x_j, y_k, z_j,k}

which is to say that "successive z-values are ordered in a x-contiguous way on a regular grid in the x and y direction" and the units in the x and y direction are specified by separate parameters (x_min, x_max, y_min, y_max).

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n_x	The number of z-values in the x-direction (the value of the key grid_x_length)
n_y	The number of z-values in the y-direction (the value of the key grid_y_length)
n	Must equal n_x n_y
x_min	The value of the key grid_x_minimum
x_max	The value of the key grid_x_maximum
y_min	The value of the key grid_y_minimum
y_max	The value of the key grid_y_maximum
Δx	= (x_max - x_min)/(n_x - 1)
Δy	= (y_max - y_min)/(n_y - 1)
i	The index of the i-th element in the list of z-values (starting at 1)
j	The index of the j-th z-value in the x-direction (starting at 1)
k	The index of the k-th z-value in the y-direction (starting at 1)
i	= (k-1) n_y + j