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/*
* =========================================================================
* colors.h - A header file to define user-defineable color parameters.
* Copyright (c) 2000 Fred M. Erickson
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
* =========================================================================
*/
/*
* This file defines the color scheme for a drawmap-generated map.
* Some limited color information is included in drawmap.h, because it isn't
* intended to be changed and because most drawing functions need it.
* The remainder of the color information is in this file, so that it
* can be collected in one place. The intent is that, if users want to
* experiment with different color schemes, they should be able to do so
* by modifying only this file, and the color map code in drawmap.c.
*
* We begin with a general discussion of the color scheme, and the
* philosophy behind it.
*
* The CIE diagram (not shown here, but readily available from reference sources)
* is a horseshoe-shaped chart that illustrates the range of colors that humans
* can perceive. CMYK printers and computer monitors roughly (but not completely)
* coincide in the portion of the CIE diagram that they occupy. They occupy triangular
* regions (with their respective primary colors at the corners) that encompass
* the center of the diagram, but don't extend to the edges of the chart. Thus,
* neither a monitor nor a printer can generally display all human-viewable colors,
* but rather only the colors that fall within their respective triangular regions.
* The triangular region for a monitor or printer is called its "gamut".
*
* In general, a spiral on the CIE chromaticity diagram is considered
* a good way to encode sequential data. The spiral begins with a relatively
* saturated version of a color and spirals inward to reach less-saturated, whiter
* colors. Since relief maps generally start with a greenish color near sea
* level, the spiral should go something like: green, yellow, orange, red,
* magenta, blue, cyan, lighter green, lighter yellow, ligher orange, lighter
* red, lighter magenta, lighter blue, lighter cyan, white.
*
* After trying the above color sequence, it appears prudent to eliminate blue
* from the rotation, because it makes it look like there are big lakes
* everywhere.
*
* Because the monitor and printer gamuts don't, in general, completely coincide,
* if we want to be able to display and print on a wide variety of hardware,
* fully-saturated colors are not a good idea for the outer portions of the spiral.
* (A fully-saturated color for a monitor, might fall outside of the triangular
* region for a printer.) We will use fully-saturated colors anyway, because they
* look good on a monitor.
*
* For elevations below sea level, it seems reasonable to run
* the spiral backwards through cyan, blue, magenta, and black, as the
* elevations proceed from 0 to the trench bottoms. For now, we aren't going
* to have any really deep depths, so we will just use cyan for any elevations
* below zero.
*
* Since most Americans prefer to deal in feet, we will use 1000-foot
* intervals, which are pretty close to 300-meter intervals. Because the DEM
* data is in meters, and because I prefer metric units, drawmap internally
* uses metric values.
*
* If we just wanted to indicate bands of elevation, the color spiral described
* above would be enough. However, we also want to give some indication of
* the variations in the terrain within each elevation band. This is normally
* done with shaded relief, in which we shade the map as if it were illuminated
* with sunlight from above one of the corners. Thus, for each color in the
* color spiral, we need to define a range of shades that will give some
* indication of light and shadow. We do this by defining color bands.
* Each band represents a single color, with 16 different intensities.
*
* The default colors are defined as follows, where the [R,G,B] values
* represent the most intense shade in each color band:
*
* Feet Color [R,G,B] Meters
* -------------- ---------- ------------- ----------------------
* Below 0 Cyan [ 60,255,255] (center of Earth to 0)
* 0 to 1000 Green [ 60,255, 60] ( 0 to 305)
* 1000 to 2000 Yellow [255,255, 60] ( 305 to 610)
* 2000 to 3000 Orange [255,165, 60] ( 610 to 914)
* 3000 to 4000 Red [255, 60, 60] ( 914 to 1219)
* 4000 to 5000 Magenta [255, 60,255] (1219 to 1524)
* 5000 to 6000 Cyan [ 60,255,255] (1524 to 1829)
* 6000 to 7000 Light Green [165,255,165] (1829 to 2134)
* 7000 to 8000 Light Yellow [255,255,165] (2134 to 2438)
* 8000 to 9000 Light Orange [255,210,165] (2438 to 2743)
* 9000 to 10000 Light Red [255,165,165] (2743 to 3048)
* 10000 to 11000 Light Magenta [255,165,255] (3048 to 3353)
* 11000 to 12000 Light Blue [165,165,255] (3353 to 3658)
* 12000 to 13000 Light Cyan [165,255,255] (3658 to 3962)
* Above 13000 White [255,255,255] (3962 to infinity)
*
* Also provided, below, is a more natural-looking color map. The user can
* select it via a command-line option.
*
* Thus ends the discussion of philosophy. We now go on to define the specifics
* of how the color table is encoded.
*/
/*
* This is the master color table for maps generated by drawmap.
*
* It is designed so that you can easily change the color scheme if you want to.
*
* The SUN rasterfile color map provides 256 RGB colors. We divide them
* into 16 color bands. This table defines how the SUN color map is filled
* with colors.
*
* Except for band 14, which is currently unused, and band 15, which is
* reserved for some special colors, the bands each represent a range of
* elevations. Within each band, there is a range of intensities for a given
* color, with each intensity representing a different steepness of terrain
* within that range of elevations.
*
* The first entry in each row of the table is an index into the SUN color map.
* Currently, these are simply spaced by 16 colors. (They are defined in
* drawmap.h.) Don't mess with them unless you really understand how the
* drawmap code works.
*
* The second entry in each row is a maximum elevation for that
* color band (in meters). For example, color band 6 is used to for coloring
* terrain that has elevations greater than the maximum elevation for color
* band 5, but less than or equal to the maximum elevation for color band 6.
* By default, color band 6 is Light Green. The red, green, and blue values
* for color band 6 are set so that the first color in that color band is
* Light Green. The remaining 15 colors in that color band are derived from
* the initial entry by simply dimming them more and more until the last color
* in the band is black.
*
* All of color bands 0 through 13 work in the same way. Color band
* 14 is totally unused, and is available for experimentation. Color
* band 15 is really not a band of colors at all, but rather just a collection
* of individually-defined colors for special uses. The colors in that
* band are bright primary colors and the like, intended for applications such as
* coloring streams bright blue and roads bright red. Changing any of
* the numbers, in color_tab, for color band 15 is a waste of time, because
* they aren't currently used. The color band 15 entry is included for
* completeness, and in case we some day want to truly use all 16 color bands
* for elevation shading. The colors for band 15 are actually defined by the
* "brights" array, further on in this file.
*
* Elevations 0 and HIGHEST_ELEVATION get some special handling. In
* particular, since elevations below 0 are rare, we simply re-use the CYAN
* from band 5 when we color a sub-sea-level point. HIGHEST_ELEVATION is
* in the mid-stratosphere to ensure that there are no land features higher
* than it is. We use HIGHEST_ELEVATION as a special flag, to set regions
* of the map to white by giving them an elevation of exactly HIGHEST_ELEVATION.
* Thus, any regions of the map for which the user does not provide DEM data,
* are initialized to HIGHEST_ELEVATION and end up as simple white background.
*
* By default, the elevations are selected so that each color band
* represents a 1000-foot range of elevations. You can change the
* elevations as you wish, as long as you follow these rules:
*
* (1) The elevation for color band 0 should always be greater than zero.
* (2) The elevation for the last valid color band (normally band 13,
* but could be band 14 if you choose to use it) must be set to
* HIGHEST_ELEVATION. (If you do choose to use band 14, you will
* need to make some simple changes in the drawmap code.)
* (3) The elevations must be arranged in ascending order.
* (4) Remember that elevations below 0 re-use the CYAN color band
* from band 5. See to it that C_INDEX_SEA_? (defined below) is set to the
* same value as the C_INDEX_? value for a CYAN color band. (Or choose
* some other color band appropriate for sub-sea-level terrain.)
*
* You can also change the default colors, by changing their red, green, and blue
* components. The default color scheme is not very "natural" since it is based on
* the CIE spiral described above.
*
* There are actually four color tables defined:
* One very-garish one based on the spiral, another more natural one that includes the colors
* typically associated with the vegetation and rocks at various altitudes,
* a neutral one that is intended to look natural without being very obtrusive, and
* one that is reminiscent of maps in school textbooks and is sort of midway between
* the spiral and the natural.
*
* The -n option selects between the tables.
*
* Of course, "naturalness" is highly subjective, and your preferred colors may be different.
*/
struct color_tab {
unsigned char c_index; // index into the color map for the start of this color band [0-255]
long max_elevation; // maximum elevation for this color band (in meters)
unsigned char red; // red component of the color for this color band [0 - 255]
unsigned char green; // green component of the color for this color band [0 - 255]
unsigned char blue; // blue component of the color for this color band [0 - 255]
};
struct color_tab color_tab_neutral[16] = {
C_INDEX_0, 305, 190, 255, 175, // LIGHT GREEN
C_INDEX_1, 610, 190, 244, 174, // interpolated
C_INDEX_2, 914, 190, 233, 174, // interpolated
C_INDEX_3, 1219, 190, 222, 173, // interpolated
C_INDEX_4, 1524, 190, 211, 172, // interpolated
C_INDEX_5, 1829, 190, 200, 170, // OLIVE GREEN
C_INDEX_6, 2134, 185, 187, 165, // interpolated
C_INDEX_7, 2438, 180, 174, 160, // interpolated
C_INDEX_8, 2743, 175, 162, 155, // interpolated
C_INDEX_9, 3048, 170, 150, 150, // BROWN
C_INDEX_10, 3353, 160, 160, 160, // interpolated
C_INDEX_11, 3658, 190, 190, 190, // interpolated
C_INDEX_12, 3962, 220, 220, 220, // interpolated
C_INDEX_13, HIGHEST_ELEVATION, 255, 255, 255, // WHITE
C_INDEX_14, HIGHEST_ELEVATION /* stratosphere */, 0, 0, 0, // currently unused
C_INDEX_15, -1 /* */, 0, 0, 0, // This line is filler --- the entries here are unused
};
#define C_INDEX_SEA_NEUTRAL C_INDEX_10
struct color_tab color_tab_natural[16] = {
C_INDEX_0, 305, 190, 255, 175, // LIGHT GREEN
C_INDEX_1, 610, 195, 237, 165, // GRAYISH GREEN
C_INDEX_2, 914, 200, 210, 156, // GREENISH ORANGE
C_INDEX_3, 1219, 205, 194, 147, // OLIVE
C_INDEX_4, 1524, 210, 178, 138, // OLIVE ORANGE
C_INDEX_5, 1829, 215, 162, 129, // LIGHT ORANGE
C_INDEX_6, 2134, 220, 145, 120, // RED ORANGE
C_INDEX_7, 2438, 207, 150, 135, // RUST
C_INDEX_8, 2743, 193, 155, 150, // DULL BROWN
C_INDEX_9, 3048, 179, 160, 165, // LIGHT MAGENTA
C_INDEX_10, 3353, 165, 165, 180, // GRAY
C_INDEX_11, 3658, 210, 210, 255, // LIGHT CYAN
C_INDEX_12, 3962, 232, 232, 255, // LIGHTER CYAN
C_INDEX_13, HIGHEST_ELEVATION, 255, 255, 255, // WHITE
C_INDEX_14, HIGHEST_ELEVATION /* stratosphere */, 0, 0, 0, // currently unused
C_INDEX_15, -1 /* */, 0, 0, 0, // This line is filler --- the entries here are unused
};
#define C_INDEX_SEA_NATURAL C_INDEX_10
struct color_tab color_tab_textbook[16] = {
C_INDEX_0, 305, 60, 255, 60, // GREEN
C_INDEX_1, 610, 150, 255, 30, // YELLOWISH GREEN
C_INDEX_2, 914, 200, 255, 0, // GREENISH YELLOW
C_INDEX_3, 1219, 218, 225, 20, // OLIVE
C_INDEX_4, 1524, 237, 205, 40, // LIGHT ORANGE
C_INDEX_5, 1829, 255, 185, 60, // ORANGE
C_INDEX_6, 2134, 255, 145, 95, // RUST
C_INDEX_7, 2438, 255, 125, 115, // RED ORANGE
C_INDEX_8, 2743, 225, 138, 150, // LIGHT MAGENTA
C_INDEX_9, 3048, 195, 152, 150, // BROWNISH MAGENTA
C_INDEX_10, 3353, 165, 165, 180, // GRAY
C_INDEX_11, 3658, 210, 210, 255, // LIGHT CYAN
C_INDEX_12, 3962, 232, 232, 255, // LIGHTER CYAN
C_INDEX_13, HIGHEST_ELEVATION, 255, 255, 255, // WHITE
C_INDEX_14, HIGHEST_ELEVATION /* stratosphere */, 0, 0, 0, // currently unused
C_INDEX_15, -1 /* */, 0, 0, 0, // This line is filler --- the entries here are unused
};
#define C_INDEX_SEA_TEXTBOOK C_INDEX_10
struct color_tab color_tab_spiral[16] = {
C_INDEX_0, 305 /* 1000 feet */, 60, 255, 60, // GREEN
C_INDEX_1, 610 /* 2000 feet */, 255, 255, 60, // YELLOW
C_INDEX_2, 914 /* 3000 feet */, 255, 165, 60, // ORANGE
C_INDEX_3, 1219 /* 4000 feet */, 255, 60, 60, // RED
C_INDEX_4, 1524 /* 5000 feet */, 255, 60, 255, // MAGENTA
C_INDEX_5, 1829 /* 6000 feet */, 60, 255, 255, // CYAN
C_INDEX_6, 2134 /* 7000 feet */, 165, 255, 165, // LIGHT GREEN
C_INDEX_7, 2438 /* 8000 feet */, 255, 255, 165, // LIGHT YELLOW
C_INDEX_8, 2743 /* 9000 feet */, 255, 210, 165, // LIGHT ORANGE
C_INDEX_9, 3048 /* 10000 feet */, 255, 165, 165, // LIGHT RED
C_INDEX_10, 3353 /* 11000 feet */, 255, 165, 255, // LIGHT MAGENTA
C_INDEX_11, 3658 /* 12000 feet */, 165, 165, 255, // LIGHT BLUE
C_INDEX_12, 3962 /* 13000 feet */, 165, 255, 255, // LIGHT CYAN
C_INDEX_13, HIGHEST_ELEVATION /* stratosphere */, 255, 255, 255, // WHITE
C_INDEX_14, HIGHEST_ELEVATION /* stratosphere */, 0, 0, 0, // currently unused
C_INDEX_15, -1 /* */, 0, 0, 0, // This line is filler --- the entries here are unused
};
#define C_INDEX_SEA_SPIRAL C_INDEX_11
/*
* Set the following parameter to the total number of color bands you have defined.
* It is a good idea if all tables have the same number of valid bands,
* but not strictly necessary if you are careful and know what you are
* doing. Note, in particular, the places in the code where MAX_VALID_BANDS is used.
*/
#define MAX_VALID_BANDS 14
#define NUM_COLOR_TABS 4 // Set this to the total number of color tables you have defined.
/*
* These are the SUN rasterfile color map values for various individual
* colors. These colors occupy the slots in color band 15, as described above.
*/
struct brights {
unsigned char c_index; // index into the color map for this color [C_INDEX_15 - 255]
unsigned char red; // red component of the color for this color band [0 - 255]
unsigned char green; // green component of the color for this color band [0 - 255]
unsigned char blue; // blue component of the color for this color band [0 - 255]
} brights[16] = {
C_INDEX_15, 210, 15, 30, // BRIGHT RED
C_INDEX_15 + 1, 50, 210, 50, // BRIGHT GREEN
C_INDEX_15 + 2, 40, 60, 190, // BRIGHT BLUE
C_INDEX_15 + 3, 0, 0, 0, // BLACK
C_INDEX_15 + 4, 120, 120, 120, // GRAY
C_INDEX_15 + 5, 255, 210, 165, // LIGHT ORANGE
C_INDEX_15 + 6, 255, 255, 255, // WHITE
C_INDEX_15 + 7, 0, 0, 0, // unused
C_INDEX_15 + 8, 0, 0, 0, // unused
C_INDEX_15 + 9, 0, 0, 0, // unused
C_INDEX_15 + 10, 0, 0, 0, // unused
C_INDEX_15 + 11, 0, 0, 0, // unused
C_INDEX_15 + 12, 0, 0, 0, // unused
C_INDEX_15 + 13, 0, 0, 0, // unused
C_INDEX_15 + 14, 0, 0, 0, // unused
C_INDEX_15 + 15, 0, 0, 0, // unused
};
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