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************************************************************************** ************************************************************************** LIQUID SPRAY INCLUDE FILE FOR PERSISTENCE OF VISION 3.x ************************************************************************** ************************************************************************** Created by Chris Colefax, 23 May 1997 1.0 INSTALLATION 2.0 QUICK START 3.0 OPTIONS 3.1 BASIC OPTIONS 3.1.1 spray_location 3.1.2 spray_direction 3.1.3 spray_strength 3.2 TIME OPTIONS 3.2.1 spray_loop 3.2.2 spray_start 3.2.3 spray_stop 3.2.4 spray_start_time 3.2.5 spray_stop_time 3.3 PARTICLE OPTIONS 3.3.1 particle_count 3.3.2 particle_life 3.3.3 particle_size 3.3.4 particle_stretch 3.3.5 particle_dist 3.3.6 particle_sep 3.3.7 evaporate 3.4 NOZZLE OPTIONS 3.4.1 nozzle_spin 3.4.2 nozzle_angle 3.4.3 nozzle_width 3.5 BLOB OPTIONS 3.5.1 use_blob 3.5.2 blob_threshold 3.5.3 components_only 3.6 ENVIRONMENT OPTIONS 3.6.1 spray_gravity 3.6.2 spray_sky 3.6.3 wind 3.7 GROUND PLANE OPTIONS 3.7.1 ground_plane 3.7.2 ground_dist 3.7.3 ground_reflection 3.7.4 max_bounces 3.7.5 ground_friction 3.7.6 puddle_thickness 3.7.7 puddle_scale 3.8 TEXTURE OPTIONS 3.8.1 spray_texture 3.8.2 spray_color_map 3.8.3 use_color_map 3.8.4 color_map_triangle 3.8.5 color_map_frequency 3.9 TURBULENCE OPTIONS 3.9.1 spray_turb 3.9.2 scale_turb 3.9.3 vel_turb 3.9.4 angle_turb 3.9.5 spin_turb 3.9.6 color_turb 3.9.7 wind_turb 3.9.8 spray_seed 3.10 OTHER OPTIONS 3.10.1 spray_clock 3.10.2 time_scale 3.10.3 flow_rate 4.0 COPYRIGHT AND LEGAL INFORMATION 5.0 CONTACTING THE AUTHOR ************************************************************************** 1.0 INSTALLATION ************************************************************************** Copy the two INC files (Spray.inc and SprayG.inc) to one of the directories (folders) in your POVRay library path. Normally this is the INCLUDE sub-directory of the directory where you installed POVRay, so if you installed POVRay in C:\POVRAY you should copy the files to C:\POVRAY\INCLUDE. On a Windows 95 system, this is probably something like: C:\Program Files\POV-Ray for Windows\Include On UNIX and similar systems, where filenames are case-sensitive, you may have to rename the include files to Spray.inc and SprayG.inc, with uppercase and lowercase as shown. This will enable you to render the sample files without modification. 2.0 QUICK START ************************************************************************** The Liquid Spray include file allows you to generate a whole range of spray-type particle objects, such as fountains, hoses, waterfalls, etc. It will even generate fireworks! There are many options you can use to affect the way the spray is generated; to use any of these you simply add the following line to your POVRay scene file: #declare [variable-name] = [value] substituting the desired variable name and value where appropriate. After you have declared all the options you want to use, you add the following line to your POVRay scene file: #include "Spray.inc" The Liquid Spray include file will then automatically create the spray object for you. Although you don't have to use any of the options (the include file will use defaults if you don't specify a variable), you will want to use the options listed below to ensure you get the sort of spray object that you want. 3.0 OPTIONS ************************************************************************** 3.1 BASIC OPTIONS ****************** The variables in this section control the basic features of the liquid spray, and should generally be the first variables you declare. 3.1.1 spray_location ********************* This vector specifies the point from where the spray object originates, ie. the point where the spray particles first appear. The default value for spray_location is <0, 0, 0> 3.1.2 spray_direction ********************** This vector specifies the direction of the spray object, ie. the initial direction of the spray particles. The default value for spray_direction is <0, 1, 0> 3.1.3 spray_strength ********************* This number specifies the strength of the spray object, ie. the initial speed of the spray particles. The default value for spray_strength is the length of the spray_direction. 3.2 TIME OPTIONS ***************** The following variables control how the spray object is animated (in relation to POVRay's clock variable). 3.2.1 spray_loop ***************** This true / false variable specifies whether or not to generate a perpetually looping spray object (for cyclic animations). If spray_loop is true, then the spray object will be visible throughout the animation, and it will have a constant spray_strength. If spray_loop is false, you can use the following options to control how the spray object is turned on or off: 3.2.2 spray_start ****************** This number specifies the time to turn on the spray object, eg. if you use spray_start = .5 then the spray will turn on halfway through the animation (presuming the animation clock goes from 0 to 1). The default value for spray_start is 0 3.2.3 spray_stop ***************** This number specifies the time to turn off the spray object, eg. if you use spray_stop = .5 then the spray will turn off halfway through the animation. The default value for spray_stop is 1 3.2.4 spray_start_time *********************** This numbers specifies the time it takes for the spray to reach full strength, eg. if you use spray_start = .1 and spray_start_time = .3 then the spray object will reach full strength at .4 The default value for spray_start_time is 0 3.2.5 spray_stop_time ********************** This numbers specifies the time it takes for the spray to turn off, eg. if you use spray_stop = .7 and spray_stop_time = .2 then the spray object will start to run down at .5, and be fully stopped by .7 The default value for spray_stop_time is 0 3.3 PARTICLE OPTIONS ********************* Each spray object contains a number of particles. You can use the options in this section to specify the characteristics of these particles. 3.3.1 particle_count ********************* This number specifies the number of particles used to create the spray object. If spray_loop is true, then the spray object will always contain the same number of particles. If spray_loop is false, then the number of particles will change as the spray is turned on and off. The default value for particle_count is 100 3.3.2 particle_life ******************** This number specifies how long each particle is alive, eg. if you use particle_life = 1.5, then each particle will disappear after 1.5 units of time. If spray_loop is true, then the spray object will be automatically adjusted so it always loops correctly. The default value for particle_life is 1 3.3.3 particle_size ******************** This number specifies the size (in POV units) of each spray particle. It is actually the radius of the spheres or blob components that make up the spray object. The default value for particle_size is 1 3.3.4 particle_stretch *********************** This number specifies how much to stretch the spray particles by. Numbers larger than one make the particle thinner and torpedo shaped, giving the effect of movement. Numbers smaller than one make the particles look like discs (not recommended). The default value for particle_stretch is 1 (ie. no stretch) 3.3.5 particle_dist ******************** This option can be used to generate a mixture of larger and smaller particles, rather than all the particles being the same size. The number used specifies the size distribution of the particles, ie. the ratio of small particles to large particles: 1 - equal numbers of small and large particles 0 - all large particles between 0 and 1 - more large particles than small particles larger than 1 - more small particles than large particles The default value for particle_dist is 1 3.3.6 particle_sep ******************* This option can be used to separate the smaller particles from the larger particles, giving the effect of a fine spray surrounding the main spray object. It has no effect if particle_dist is 0. Setting particle_sep to 0 specifies no separation between the differently sized particles, while numbers larger than 0 increase the separation. The default value for particle_sep is 0 3.3.7 evaporate **************** This number specifies the rate of evaporation of the particles. Setting this option to 0 specifies no evaporation, while numbers larger than 0 will cause the particles to grow smaller until they disappear at the end of their lives (see particle_life above). The larger the number, the faster the particles disappear. The default value for evaporate is false (0) 3.4 NOZZLE OPTIONS ******************* The following options control the characteristics of the spray nozzle: 3.4.1 nozzle_spin ****************** This option specifies the number of spins the nozzle makes per unit of time. Setting nozzle_spin to 0 will stop the nozzle from spinning. Negative numbers can be used to spin the nozzle in the opposite direction. The default value for nozzle_spin is 1 3.4.2 nozzle_angle ******************* This option specifies the angle (in degrees) of the spray nozzle. If you think of the spray object as a cone, with its apex at spray_location, this number is the angle at the apex of the cone (similar to the radius option in POVRay's spotlight). The default value for nozzle_angle is 20 3.4.3 nozzle_width ******************* This option can be used to widen the nozzle, for waterfalls and other similar spray objects. The default value for nozzle_width is 0 3.5 BLOB OPTIONS ***************** Normally the spray object is generated as a union of spheres. You can use the following options to generate the spray object as a blob object instead: 3.5.1 use_blob *************** Setting this option to true will cause the spray object to be generated as a blob. The default value for use_blob is false 3.5.2 blob_threshold ********************* This number specifies the threshold of the blob used to create the spray object (see the POVRay docs for more information on blob thresholds). The default value for blob_threshold is .5 3.5.3 components_only ********************** This option can be used to generate blob components only, rather than a complete blob object. This is useful when you want to combine the liquid spray blob with another blob (so the components interact). You will have to place the include statement inside the blob {} object, and apply textures manually. For an example of this, see the sample scenes that came with the Liquid Spray include file. The default value for components_only is false 3.6 ENVIRONMENT OPTIONS ************************ The following options can be used to alter the environment in which the spray object is created: 3.6.1 spray_gravity ******************** This number specifies the strength of the gravity force applied to the spray particles. Only positive numbers are accepted; the gravity force is always in an opposite direction to the spray_sky vector. The default value for spray_gravity is 9.8 3.6.2 spray_sky **************** This specifies the direction vector that points in the up direction. It works in a similar way to the sky keyword in the POVRay camera, and it useful when using a different coordinate system (eg. use spray_sky = z if the z-axis points upwards). This vector determines the direction of the gravity (opposite to the sky, of course) and is also used as the normal of the ground plane, if one is specified (see section 3.7). The default value for spray_sky is <0, 1, 0> 3.6.3 wind *********** You can use the wind option to blow the spray particles in a particular direction. The direction of the wind vector is the direction in which the wind blows, and the size of the wind vector determines the strength of the wind force. The default value for wind is <0, 0, 0> (no wind) 3.7 GROUND PLANE OPTIONS ************************* The Liquid Spray include file has the ability to add a ground plane to the scene. If a spray particle hits this ground plane it can automatically splash off it or it can form puddles on the plane. Note that the Liquid Spray include file will not actually create a ground plane object for you, giving you the option to use any sort of object you like to represent the ground. 3.7.1 ground_plane ******************* This is a true/false value that indicates whether a ground plane is present or not. The default value for ground_plane is false 3.7.2 ground_dist ****************** This specifies the distance of the ground from the origin, and is the same as the distance value as specified in the plane object. Note that the normal direction of the plane is always the same as spray_sky. The default value for ground_dist is 0 3.7.3 ground_reflection ************************ This specifies the amount of energy a spray particle retains after splashing off the ground plane. Setting ground_reflection to 1 means that the particle retains all its energy, and will bounce back to the same height each time it splashes. Setting ground_reflection to 0 means that the particle retains none of it's energy after hitting the plane, and therefore it forms a puddle. Values in between 0 and 1 will cause the particle to splash less high each time it hits the plane, eventually coming to a stop. The default value for ground_reflection is .8 3.7.4 max_bounces ****************** This option specifies the maximum number of times a spray particle will splash off the ground plane before forming a puddle. The default value for max_bounces is 1 3.7.5 ground_friction ********************** After a spray particle stops splashing it will form a puddle which slides along the ground. The ground_friction options specifies how quickly the spray particle stops moving after it forms a puddle. Setting this option to 0 causes the particle to stop as soon as it hits the ground. Setting this option to 1 causes the particle to slide along without stopping. Numbers in between 0 and 1 bring the particle to a gradual stop. The default value for ground_friction is .5 3.7.6 puddle_thickness *********************** This number specifies how thick the puddles formed by the spray particle will be. Setting this option to 1 means that the puddles are as thick as original particles, while smaller numbers make the puddles thinner (and wider). The default value for puddle_thickness is .3 3.7.7 puddle_scale ******************* You can use this option to artificially alter the size of the puddles, eg. puddle_scale = 2 will make the puddles twice as large as normal. This is most useful when using blobs (see section 3.5 above), as thin blobs can sometimes cause rendering problems. The default value for puddle_scale is 1 (no change in puddle size) 3.8 TEXTURE OPTIONS ******************** The following options can be used to change the texture and colour of the spray object and its particles: 3.8.1 spray_texture ******************** This specifies the texture used for the spray object. You can use the name of a predefined texture, eg: #declare spray_texture = MyTexture, or you can specify a complete texture within a texture {} statement. By default a plain blue texture is used. 3.8.2 spray_color_map ********************** You can use this option to change the color of the spray object over time. This option should be declared as a standard color_map, eg: #declare spray_color_map = color_map {[0 rgb <1, 1, 1>] [1 rgb <0, 0, 0>]} This will cause the spray to gradually change from white at the beginning of the animation, to black at the end of the animation. 3.8.3 use_color_map ******************** You can set this option to false to turn OFF the color_map if you are creating multiple spray objects and have already declared spray_color_map, which you no longer want to use. 3.8.4 color_map_triangle ************************* Setting this option to true will cause the color_map to go from 0 to 1, and back to 0 (just like using the triangle_map pigment option). This is the default if spray_loop is true; otherwise, the default value for color_map_triangle is false. 3.8.5 color_map_frequency ************************** Normally the first color of the spray_color_map is used at the beginning of the spray, and the last color is used at the end of the spray. You can change this option to have the color_map repeat itself more than once through the life of the spray object, using color_map_frequency = 5 will make the color_map loop through 5 times. 3.9 TURBULENCE OPTIONS *********************** The options is this section can be used to add randomness to certain aspects of the spray object. You can use these options to make the spray object more (or less) realistic. 3.9.1 spray_turb *************** This option controls the overall amount of turbulence added to the spray object. Good values range from 0 (no turbulence) to 1 (lots of turbulence), but any value can be used. Changing this value will add equal turbulence to all aspects of the spray object. If you wish to adjust the turbulence of individual areas of the spray object you can use the following parameters. (Note that all the individual turbulence options are multiplied by spray_turb to find the final turbulence, so you will have to make sure that spray_turb is not 0 before using the other turbulence options). The default value for spray_turb is 0 3.9.2 scale_turb ***************** This option controls the amount of turbulence added to the scaling of the spray particles. It is specified as a factor of the particle size, eg. scale_turb = .5 will give particles scaled up to 50% larger or smaller than normal. 3.9.3 vel_turb *************** This option controls the amount of turbulence added to the velocity of the particles. It is specified as a factor of the particle velocity, eg. vel_turb = .3 will give particles with velocities up to 30% more or less than normal. 3.9.4 angle_turb ***************** This option controls the amount of turbulence added to the nozzle angle. It is specified as a fraction of the nozzle_angle option, eg. angle_turb = .4 will give particles with nozzle angles up to 40% more or less than normal. 3.9.5 spin_turb **************** This option controls the amount of turbulence added to the nozzle spin. It is specified as a fraction of 360 degrees, eg. spin_turb = .1 will give particles that spin up to 36 degrees away from normal. 3.9.6 color_turb ***************** This option controls the amount of turbulence added to the color_map. color_turb = 1 means that colors will be picked randomly from the spray_color_map to color each particle. 3.9.7 wind_turb **************** This option controls the amount of turbulence added to the wind direction. It is specified as a fraction of 360 degrees, eg. wind_turb = .2 will give particles that are blown up to 72 degrees away from normal. 3.9.8 spray_seed ***************** This option specifies that random number seed used when adding turbulence to the spray object. Normally this is 0, but any integer value can be used. 3.10 OTHER OPTIONS ******************* 3.10.1 spray_clock ******************* This option specifies the clock value you want to use to generate the spray object. By default this is equal to POVRay's internal clock, so you shouldn't normally have to use this option. However, there are a number of interesting effects you can achieve by using the spray_clock. If you use spray_clock = .6, you will get a still scene of the spray object, as it would look at .6 units of time. You can also use functions of the internal clock, eg: #declare spray_clock = 1 - clock will give you a spray object that animates backwards. 3.10.2 time_scale ****************** This option behaves differently, depending on the spray_loop option. If spray_loop is true, then time_scale changes the time taken for the spray object to complete one loop, eg. time_scale = 3 will make the spray object loop three times per unit of time, rather than once. If spray_loop is false, then time_scale gives the effect of increasing (if you use a number larger than 1) or decreasing (if you use a number smaller than 1) the speed of the spray_particles. However, it has no effect on the spray_start, spray_stop, spray_start_time, or spray_stop_time options. The default value for time_scale is 1 3.10.3 flow_rate ***************** This option can be used to change the flow rate of the spray object, where 0 is off and 1 is full strength. Numbers between 0 and 1 give less than full strength, while numbers larger than 1 give more than full strength. Normally if you want to turn the spray object on or off you will use the options listed in section 3.2. However, you can use the flow_rate option to create different effects, eg: #declare flow_rate = sin(clock * 4 * pi) * .5 + 1 will give an oscillating spray object. 4.0 COPYRIGHT AND LEGAL INFORMATION ************************************************************************** The Liquid Spray Include File, including Spray.inc, SprayG.inc, all documentation, and associated sample POV files are Copyright 1997 by Chris Colefax. Full permission is granted to the user to modify any or all of the files for his/her own use. If modified versions are to be distributed the user should make clear the modifications that have been made by him/herself. The Liquid Spray Include File may be bundled with or without other software on CD-ROM collections, Bulletin Board systems and other file archives, providing that all associated files, including documentation and samples, are included. I would also request that persons intending to distribute the Liquid Spray Include File in this manner or otherwise would first contact me (see below for contact information) to ensure that they are in possession of the latest version. 5.0 CONTACTING THE AUTHOR ************************************************************************** If you wish to contact me with bug reports, bug fixes, criticisms, comments, suggested improvements, questions, etc. you can reach me by email at: ccolefax@geocities.com or by regular mail at: Chris Colefax PO Box 110 Kuranda, Queensland Australia 4872 ************************************************************************** POV-Ray(tm) and Persistence of Vision(tm) are registered trademarks of the POV-Ray Team(tm)