POVMAN

Roofing Tiles

2006-07-03T00:32:00.000-07:00

I was after a pattern to represent roof tiles. I've tried the cells pattern before but is was never quite what it wanted. Here's what I came up with...

#include "colors.inc"
camera { location <15,20,-30> look_at <0,0,0>}
light_source{<-50, 100, -50>color White}
background { color <0.25,0.35,0.80> }
#declare myPatt = function(x,y,z){(y - int(y)) - (int(x)/2)};
box{<-10,-10,-10>,<10,10,10>
rotate <45,0,0>
texture {
pigment { function {myPatt(x,y,z)} pigment_map{[0 White][1 Black]}} scale 2 translate <10,0,0>}
}

Pigment Pattern Isosurface

2006-06-16T05:03:00.000-07:00

I was looking through the "functions.inc" file the other night when I noticed that a function can be based on a evaluating a pigment. I knew you could create a pigment based on the object pattern, so...

I thought it might be possible to create an isosurface that evaluates an object pattern pigment.

A quick question on the news groups and the kind people there told me it would be possible but slow.

So I can now build a complex CSG shape, put it in an object pattern pigment, put that in a function and have an isosurface built to my specs.

But!, you ask , why would you do that if it's slow and you have already buit the shape in CSG? The answer is that I could add noise to the pattern. This might work well for a weathered statue. So I'll be giving this a try in the next couple of days, and let you know how it turns out.

Clipping

2006-06-14T00:54:00.000-07:00

Interesting side affect of using the "clipped_by". I had an object thatwas made up of a Cylinder and two spheres, I wanted to chop off the front edge, and on a whim I decided to use the "clipped_by / bounded_by" method discussed in the manual.

Rather than just shearing the front of the object as I expected it cut the object open, exposing the interior of the shape.

The more normal method of using a "difference" does not expose the inside.

This might be worth experimenting with!

Aspect Ratio

2006-06-09T01:02:00.000-07:00

A Little known ( or at least little used ) feature of the camera is the Aspect ratio. I've used this in the past when I've rendered a non-standard size image. If you make and extra wide image you have to widen the aspect ratio or the image gets deformed.

Anyway, last night I actually used the aspect ratio to create an effect rather than avoid one.

I placed the camera close to the nose of a sheep. By playing with the aspect ratio I was able to get one of these "HUGE NOSE" shots you sometimes see on TV. There are other ways to get the same effect by changing the camera type for instance. However as POV-Ray is an ongoing learning experience every idea is a new arrow for your bow.

To change the aspet ratio, include the "up" and "right" settings in your camera block.

up <0,1,0> right <1,0,0>

Clouds Macro

2006-06-02T00:23:00.000-07:00

I'm currently working on a macro to produce clouds. It s not finished yet so I cant post anything but you might find the principal interesting.

Currently I pass the macro a Size,Count, Samples,Seed and Flat-Bottom parameters.

Size is the length of the side of a box in which the could will appear ( the macro returns a box with a cloud in it).

Count is used to produce a blob made with a number of spheres equal to the count. This Blob is then used in an object pattern media statement in the box.

Samples is the number of samples used by the media.

Seed is the random seed value used by macro to place blob elements.

Flat-Bottom if true, is used used to move most of the blob spheres in the bottom third of the box, upwards, in effect flattening the bottom of the cloud.

Overall its going quite well. But sadly as media takes so long to render the macro is going to take a lot of effort to perfect. I will post it when finished.

Tilting the Camera

2006-05-23T00:32:00.000-07:00

POV-Ray by default tries to keep the camera level in the x-z plane, which keeps your images "upright". Well, in the image mentioned in the previous post I wanted a creepy camera angle so I deliberately tilted the camera.

camera { location <4,7,-35> rotate z*5
look_at <0,> }

There you are, nice and simple, a 5 degree tilt on the camera.

Fire

2006-05-22T04:38:00.000-07:00

Well I've just posted my latest image in the news group that included lots of burning flames, look for "My Basement".

http://news.povray.org/povray.binaries.images/

These were done with media, and as media is such a P.I.T.A. I thought I'd post the code here with some info about what its doing. Hopefully anyone reading this will find it helpful.
difference {
sphere { <0,0,0>, 1 }
box { <4,0,4>, <-4,-4,-4> }
hollow
scale <2,20,2>
interior {
media {
intervals 5
samples 5
emission .6
density {
spherical
scale <3,20,3>
warp {
turbulence <.8,.07,.05>
}
density_map {
[0 rgb 0]
[.5 rgb 0]
[.6 rgb Orange]
[.7 color Yellow]
[.8 color Yellow]
[.9 color White]
[1 color White ]
}
}
}
}
texture {
pigment {
Clear
}
}
translate <0,5,0>
}

The Explanation.

I decided to create the burning flame inside a sphere, but as the flame is sitting in a dish in the final scene I used the difference to cut off the bottom of the sphere.

The Object has to be "hollow" to show the media.

The CSG is stretched vertically so that the flame can be tall. Note stretching the containing CSG will not effect the shape of the media!

Intervals and samples are set fairly low to speed rendering, increase these for final render. If you set these lower then the media becomes blocky, as if its made of layers. (YUK!)

emission is set to .6 so that the flames will be transparent, if set to 1 then the flame would appear solid.

The pattern dor the density is "spherical" basicly the overall shape I want is a stretched sphere so that from above the flame is round, and from the side, taller than it is wide.

The sphereical pattern is then stretched up and down to make the flame taller rather than a round ball.

The Warp is used to turbulate the pattern. Without this the media would appear as a perfect ball, that had been stretched by the scale statement above.

The density map is the trick. This defines the colors used in the flame. Density 1 represents the center of the pattern (sphere) and density 0 is outside the ball. Note here the useage of the "rgb 0", this is effectively no color, that is transparent. This is used to prevent the flames reaching the edge of the containg CSG. the flames would be cut off by the edge of CSG, so this needs to be prevented. Alternatively you could scale the pattern down.

Missile Source Code

2006-05-12T00:36:00.000-07:00

I've recently donw a scene of a missile in flight. I've posted the SDL below, but knowing this Blog software it wont be formatted correctly, but there you go. You can get a better copy of the SDL over at the POV-Ray news groups, link on the right. There are a few interesting points I can raise about the resulting code, but I'll mention these in later posts ( if I remember )

To Note (note to self) my first ever use of light_group and object pattern media.

#include "colors.inc"
#include "glass.inc"
#include "stars.inc"
#include "shapes.inc"
#include "functions.inc"
#declare showFire = true;
#declare showSmoke = true;
camera {
// location <0,0,-25>// look_at <10,>
location <-40,-25,-25> look_at <0,>
// location <0,20,-1>// look_at <0,>
}
global_settings {max_trace_level 12 }
light_source { <-500, 2000, -500> color White
//area_light <50,0,0>,<0,0,50> 3,3
//jitter
//adaptive 1 media_interaction on media_attenuation on }
background { color <0.25,0.35,0.80> }
light_group {
union {
// sensor
box { <0,>, <-.1, -.2, -.2>
texture { pigment { leopard scale <20,.01,.01> pigment_map { [0 Orange*1.2] [.099 Orange*1.2] [.1 Black] [1 Black] } } finish { specular .1 roughness .001 ambient 0 } } } // glass sphere sphere { <0,0,0>,.4 scale <.7,1,1> interior{ ior 1.4 } texture { pigment { //Clear rgbt <0.858824,0.576471,0.439216,.9> } finish { specular .5 roughness .1 reflection { 0..5 } ambient 0 } } } // missile body union { cone { <0,0,0>,.5, <3,0,0>,1 } cylinder{ <3,0,0>, <9,0,0>,1 } cone { <9,0,0>,1, <13.5,0,0>,1.4 } cylinder{ <13.5,0,0>, <20,0,0>,1.4 } cone { <20,0,0>,1.4, <21.5,0,0>,1 } #declare r1 = 0; #while(r1 <>,<1,0>,<1,.8> rotate <-90,0,0> translate <4,1,0> rotate scale 1 } #declare r1 = r1 + 1; #end #declare r1 = 0; #while(r1 <>,<5,0>,<5.2,.8>,<4.9,1.8>,<2,1.8> rotate <-90,0,0> translate <14,1.4,0> rotate scale 1 } #declare r1 = r1 + 1; #end texture { pigment { White *1.5 }//*1.5 finish { specular .2 roughness 0.001 ambient 0 } normal { bumps scale .0001 bump_size .01 } } } translate <-21.5,0,0> rotate <30,0,0> }
#if(showSmoke = true)// smoke oject #declare pObject = union { cone { <2,0,0>,0, <15,0,0>,2 } cylinder{ <15,0,0>, <1000,0,0>,2 } };
//smoke trail cylinder { <2,0,0> <1000,0,0>, 4 hollow interior { media { intervals 5 //5 higher slows it up and gives smoother images samples 5 //5 lower = more blocky method 3 absorption 0.2 scattering { 1,color Gray25 extinction .4//1.2 //amount of above color subtracted as it passes through, darkens the cloud } density { pigment_pattern { object {pObject}} // pattern of the media warp { turbulence <.5,1,1> } color_map { [0 rgb 0] [.45 rgb 0] [.5 rgb 1] [1 rgb 1] } } } } texture { pigment { Clear } } }#end
#if(showFire = true)//jet exhaustdifference { sphere { <0,0,0>, 1 } box { <0,4,4>, <-4,-4,-4> } hollow scale <40,2,2> interior { media { intervals 5 //5 higher slows it up and gives smoother images samples 5 //5 lower = more blocky emission .3 //1 brightness of glowing media density { spherical scale <50,3,3> warp { turbulence <.8,.07,.05> } density_map { [0 rgb 0] [.6 rgb 0] [.7 color Yellow] [.8 color Yellow] [.9 color White] [1 color White] } } } } texture { pigment { Clear } } }
//cloud scape#end
light_source { <0,> color White*.1 media_interaction off media_attenuation on }global_lights on}// end of light_group

union { plane { y, 260 texture { finish {ambient 0 diffuse 0.7} pigment { bozo turbulence 1.00 translate 200*y color_map { [0.5, rgb 1 transmit 1.0] [1.0, rgb 1 transmit 0.6] } scale 0.125 } scale 1500 } } plane {y, 240} texture { finish {ambient 0 diffuse 0.7} pigment { bozo turbulence 0.35 translate 300*y color_map { [0.5, rgb 1 transmit 1.0] [0.8, rgb 1 transmit 0.5] } scale 10 warp {turbulence 0.7} scale 1/10 scale 0.125 } scale 2500 } texture { finish {ambient 0 diffuse 0.5} pigment { bozo turbulence 0.35 translate 400*y color_map { [0.5, rgb 1 transmit 1.0] [0.8, rgb 1 transmit 0.4] } scale 10 warp {turbulence 0.7} scale 1/10 scale 0.125 } scale 2500 } hollow double_illuminate //scale 1/200 no_shadow translate <0,0,100> rotate <40,0,-20>}
//end of scene

...just as I figured a disordered mess.

SOTW Released and SDL-Switch

2006-05-08T00:41:00.000-07:00

Well, its here at last. Spaceship Of The Week has been released. I've posted the macros over in the POV-Ray news groups, and also a few samples. Although, thanks to A goof up with Outlook Express, I think I may well have posted the images twice, cane really be sure at this point.

An interesting point to note is I goofed at one point withan SDL Switch Statement and forgot to put a "#break" at the end of a "#range" statement and the code simple dropped straight through to the next "#range", meaning the code in both sections ran. I hadn't expected that!

Thats something I'll be using in future.

SOTW Light Surprise

2006-04-27T04:47:00.000-07:00

OK so I have up to three area lights randomly rotated around the Space Ship. Last night I change the random seed value, havn't done that for a few renders, and suddenly all the light sources are on the far side of Space Ship.

The nearside of is not lit. I realised what had happend about 10 rows into the render and was about to stop it rendering...

... when I had to let the dog out. So I come back and the render is finshed. WOW! Fantstic effect, all of the structures on the Ships surface are back lit with no forward detail shown.

The moral of the story, I guess, is dont stop renders that you can leave. The result might be unexpectedly good.

SOTW Continues

2006-04-25T05:28:00.000-07:00

Man Oh Man. I've discovered that completely random textures are resulting in awful, terrible, in fact rubbish results, when applied to space ships. I think I'm goige to have to come up with a few set "finish" statements, a few patterns, and a few pigments and randomly apply these.

It seems to be a case of expectation. What you expect to see on a spaceship effects your interpretation. So the Yellow and Purple leopard pigment with stretched agate normal is out, and the slick gray cells pattern is in.

SOTW Continues

2006-04-20T04:59:00.000-07:00

The SOTW project is going on. Huge props and thanks to the guys on the POV-Ray news groups who pointed me at the Reorient_Trans function which can be found in one of the standard includes.

I needed the function to position various Widgets on the Hull surface. I was using the Trace function to fire rays at the hull from random directions which was giving me the location of the hull-ray intersection. So I was able to translate my Widgets to the location.

Unfortunatley my Widgets where not rotated perpendicular to the hull surface and the result was awful!

The simple wonderfull answer was to use the fourth parameter on the trace function, store this into a variable and then pass it to the Reorient_Trans function, which gave me the rotation I needed.

Thanks you guys!

A Dirty Wall

2006-04-19T03:31:00.000-07:00

Not a real tutorial but a guide, or something like that.

Anyway the sad thing is that the medium of Blogging has not caught up with POV-Ray SDL formatting I like to use ( lots of tabs ) so sadly all my nicely laid out code has had to be compressed and streamlined to fit on the blog. Sad.

The code below shows the process I followed recently when I wanted to make the bottom of a wall, dirty. You know, when all the splash and muck splats along the bottom of a wall.

This scene shows the basic stages of texturing the wall. If you render the scene as is, then change the value allocated to "stage" from 1 to 2 and render again you'll see what change I made. You change the value of thru the range 1 to 9, as I've included 9 main stages in building the texture. I've included comments in the code so that you can see what I've changed and why.

#include "colors.inc"

camera{location <0,1.2,-5>look_at<0,1,0>}
light_source {<-50,100,-50>color White}
background { color <0.25,0.35,0.80> }
plane {y, -1 pigment{color rgb <0.7,0.5,0.3>}}
#declare stage = 1; //change from 1 through 9

// basic brick texture to start with
#if(stage=1)
#declare wallTexture = texture {pigment {brick}};
#end

// shrink the brick pattern as its too big
#if(stage=2)
#declare wallTexture = texture {pigment {brick scale .2}};
#end

// add in the second texture that will be the mud/dirt
#if(stage=3)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {pigment {marble // parralel lines of colour
pigment_map {
[0 Clear] // transparent
[1 Black] // muddy color}}};
#end

#if(stage=4)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {
pigment {
marble rotate <0,0,90>// rotate pattern so it lines up with floor
pigment_map {[0 Clear][1 Black]}}};
#end

#if(stage=5)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {pigment {
marble rotate <0,0,90>
scale 5 // enlarge the pattern
pigment_map {[0 Clear][1 Black]}}};
#end

#if(stage=6)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {
pigment {
marble
rotate <0,0,90>
scale 5
translate <0,1.4,0> //translate the pattern so densest part is on the floor
pigment_map {
[0 Clear]
[1 Black]}}};
#end

#if(stage=7)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {
pigment {
marble
rotate <0,0,90>
scale 5
translate <0,1.4,0>
pigment_map {
[0 Clear]
[.6 Clear]// extend Clear area
[.9 Black] // extend the solid part
[1 Black]}}};
#end

#if(stage=8)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {
pigment {
marble
rotate <0,0,90>
scale 5
translate <0,1.4,0>
warp{turbulence <0,.5,0> } // turbulate the pattern
pigment_map {
[0 Clear]
[.6 Clear]
[.9 Black]
[1 Black]}}};
#end

#if(stage=9)
#declare wallTexture = texture {pigment {brick scale .2}}
texture {
pigment {
marble
rotate <0,0,90>
scale 5
translate <0,1.4,0>
warp{turbulence <0,.5,0> }
warp{turbulence <1,0,1> } // additional turbulence 'cos I had to tinker
pigment_map {
[0 Clear]
[.6 Clear]
[.9 Black]
[1 Black]}}};
#end

box {<-2,-1,0>,<2,2,.1>texture { wallTexture }}

SOTW Current Project

2006-04-12T04:59:00.000-07:00

Well I've just started a new project. I'm calling it Spaceship Of The Week. I'm taking my lead from the now classic Landscape Of The Week that was flying around the Message Boards a few months back.

The LOTW was a set of macros that took a random seed value and produced a random landscape, complete with sky, trees and rocks. The end results were fantastic.

I recently knocked up a sci-fi "Lodge ship" which used random features to decorate a cylinder, including windows, lights, radio masts, and misc' blocks of unknown purpose. Each of these items was crafted to my specific needs in this case. But I was inspired to see what I could do with it.

So I started with an SDL file called "SOTW". This includes a light, camer a couple of standard includes.

Next I created another include that I've called SOTWSpace. This returns a huge hollow sphere populated with a random selection from the "stars.inc" include that comes with POV-Ray, I intend to add a few more options to this file later.

Next I created another include called "SOTWHull" which returns a random basic shape for the ships hull. This is what I'm working on at the moment. So far it selectes a random primative, which it then rotated, scaled and sheared a random number of times.

Sadly the results so far are far from good. I keep getting shapes that are too thin for my liking. I need to modifiy the weighting of the random transformations to prevent it returning extreems.

I could justify the extreem hull shapes by saying anying it viable without atmosphere, but you know, some things just dont look right. even when they are.

I've a long way to go yet, I'll try and kep you "Posted". Any suggestions for this set of macros will be gladly read...

Tip 18

2006-04-10T04:52:00.000-07:00

This ones a no-brainer to old POVers but it's something I did this weekend and I thought I mention it here.

I was rendering a scene with many chess pawns in it but wanted one to stand out. I didn't want to change the scene lighting by spotlighting the pawn in question. Instead I used a simple and sometimes subtle ambient setting on the pawn in question.

All of the other pawns had an ambient of zero, but I gave this pawn an ambient of 0.2 .

The result was slight "enhancing" of the one pawn. Not too much, not too obvious, but enough to draw the eye, which is what I wanted.

Oh the frustration...

2006-04-04T04:49:00.000-07:00

Ok, so I'm doing a space ship. Its a large space ship, so I want to give it a focal point. Fine, no problem. Suddenly the Starfield background stars disapear. Perhaps I'm not destined. Oh hang on. Maybe if I build a CSG lens in front of the camera I can get the same effect without all of the star loss...

Should have studied optics at college.

Podcast by POVers

2006-03-30T03:37:00.000-08:00

Dont let me mislead you with the title of this post. The Podcast I'm talking about is not about POV-Ray, its about table top gaming. ( Gaming in the "Monopoly" sence, not the "betting" sence). It just happens to be produced by two people who use POV-Ray. The Podcasts web page even has a rendered image as its banner.

http://www.roll2d6.com/

Tip 17 A Cheat

2006-03-27T04:14:00.000-08:00

It's OK to cheat POV-ray, it doesn't mind.
What I'm getting at is that sometimes it takes too long to model a "thing". The time it would take to model is just not worth it.

You want an example?

Well... I was modeling a spaceship and I needed a series of lights on posts to circumnavigate to hull. The Post was a simple cone and I wanted the light to be a Red Glass sphere on top of the cone.

Now I could have spent time putting a light in a clear sphere and playing with the texture of the sphere until it glowed red.

Frankly the size of the object did not warrant the effort that would have taken.

So I made the sphere have a plain Red pigment with a .5 ambient setting that makes it look alight and stuck a point light above the sphere to get the illumination. Incidentally I had top include "no_shadow" in the sphere's definition so that I didn't get a shadow underneath the sphere fom the light above it.

Plain and simple, I cheated. It worked. It looks good. Who'll know?!

Tip 16 Coloured Fog

2006-03-22T05:14:00.000-08:00

A number of times I've tried to add "atmospheric media" to a scene to give it some , well, atmosphere, this is slow when it comes to rendering.

A quick alternative is to use the "fog" object. There is a lot that can be said about fog, and I probably will some day. But for now, just consider this. If you use a coloured fog rather than the standard gray-white, can you add an unusual/special feel to your image.

For example, a week yellow fog can add the golden feel you get on a sunny afternoon, or a blue one can add that twilight feel.

Tip 15 KIS

2006-03-07T05:50:00.000-08:00

OK, heres a real quicky. Is it close to the camera? No? Well forget the detail. Keep It Simple.

When an object if far from the camera, dont bother modeling all of the details, you probably wont be able to see all of them. Also keep in mind the time it takes to render complex textures. It sometimes pays to keep distant textures simple.

There is artistic merit in this as well, because if its in the distance it's not likely to be the focus of the scene and too much detail will distract the eye.

Tip 14 Clear going black.

2006-02-16T05:01:00.000-08:00

A common problem we all hit at some point, is that we create a scene with lots of Clear/Glass objects.

Well thats not the real problem. the problem is that sometimes these render with some or all of the objects turned black. It's a nasty black, not shades of black, just plain horrid black.

The common cause is that the max_trace setting is not high enough.

What happens is that each time a ray passes through one of these objects it splits. So to prevent a scene from taking forever to render the maximum number of "splits" on any one ray is quite limited. If you up the value of "max_trace" you'll start to see the black disapear.

Tip 12a Filling in the Blanks

2006-02-15T05:07:00.000-08:00

Hi. This is 12a because that other number is a bit unlucky.

The Tip today, is to use a "fill" light. A Fill light is not some POV-Ray object but rather a concept for lighting scenes. Still and Video people know all about Fill lights.

Basicly a fill light is (usually a dim and unfocused light that adds depth to a scene. If it's done properly then you generally dont even know its there.

A Fill light is often set to the side or rear of the "subject". It gives definition and depth to background. Sometimes it gives definition to the "subject" with a low level of back-lighting.

Below is my standard fill "light_source", I call it "the Daniel Prust", as he was the guy who gave it to me. I've used the Daniel Prust in so many scenes I consider it a standard.

light_source { <-70, 20, -15> color rgb <0.2,> shadowless }

Tip 12 Realism with area_light.

2006-02-14T05:41:00.000-08:00

There is a simple tip for adding realism to your scene.

Use "area_light"!!!!!!!!

This alone will not make a scene real. but when you've finished modeling and the textures are just right, hit the whole thing with area_light.

Make all your "light_source"s into what I call "High Def" area lights, that is to say using big numbers in the array of lights. My final renders usually end with 25 x 25 area_light's. This gives you some good strong shadows, and pen umbra, with very little chance of the specking effect you can get with lower numbers.

There are a whole bunch of "realism" tips, of which this is only one. But every little helps...

Tip 11 Fading your lights

2006-02-13T04:53:00.000-08:00

When you set up a scene, I would recommend that you always ensure that you set the fade_distance and fade_power on your light_source(s) when nearing completion.

As a rule, unless you only light source is the Sun you should do this. Why? because it gives the scene a feeling of depth and realism.

Even if the Sun is your light_source, and the scene is set in a room, adding a fade to the light still adds that little-something to the amount of reflected light.

If you havn't used the fade settings, stick a light_source next to a plane and you'll see the effects easily.

Tip 10 Include files

2006-02-10T04:37:00.000-08:00

Okay, heres a tip for the man who going to be poving for a long time. When you finish an object, say a chair or a mug, or a spaceship create an include file for it.

For instance if you have a "mug" save just the code to create the mug into a file called "mug.inc".

Now you can use that include file in any future scene easily by using the "#include" syntax.

Rather than just copy the outer most "union" or "merge" or "difference" into the include file, declare it as a variable so that you can call it with the "object" syntax.

So in your include file...

#declare povmanMUG = union { blar blat blud };

... and then in you new scene you would put...

object { povmanMUG }

Now theres one little thing you might want to keep in mind.

Declare any textures for the object you in the include file as well. That way you dont have to look through all of your pov files scanning for "that texture you used 3 months ago".

Tip 9 Media and Hollow

2006-02-09T05:09:00.000-08:00

A quick tip for you, if you intend to use media in a scene.

I dont know how many scenes I've made where I've tried to use media and spent a frustrating length of time wondering why my media does not appear when rendering.

Invariably there is one cause.

Something in the scene is not declared as "hollow".

So the tip is, if you use media, make every object "hollow", especially any "plane" objects, and save yourself some heart-ache.

Tip 8 Optioning Scene Elements

2006-02-08T00:40:00.000-08:00

When I'm developing a scene I sometimes find that particular elementssuch as an Isosurface, some media or even a light source are causing the render time to increase significantly.

If I'm not actually working on that slow bit of the scene, I turnit off, so that its not being rendered every time I try and tinker with something else.

I've put an example below. In this mini scene I have a light source that can optionally turn on or off its area_light settings. This has a huge impact on the render time.

The important bit here is"#declare showAreaLights = no;" which I use to turn off the area_lights settings. Render the scene, then change the "no" to "yes" and render again, you'll see the huge speed difference.

If you look at the SDL you'll see that I have put an "#if"statement in the middle of the light_source declaration that only includes the area_light details if the value of "showAreaLights" is set to "yes".

In a big scene I might easily have 20 various things that I can turn on or off.

A common thing I do is have a set of development light sources that I turn on while tinkering with a scene so that I can see everything from every angle, awhich I then turn off during final rendering.

#include "colors.inc"
#include "glass.inc"
#include "stars.inc"
#include "shapes.inc"
#declare showAreaLights = no;
camera {location <0,1,-5> look_at <0,0,0>}
background { color <0.25,0.35,0.80> }
plane {y, -1 pigment { color rgb <0.7,0.5,0.3> }}
sphere { <0,.5,0>,1.5 texture { pigment { Red } normal { agate scale .2 } finish { ambient 0 specular .1}} }

light_source { <-50, 100, -50> color White
#if(showAreaLights = yes)
area_light <3,0,0>,<0,0,3>,25,25
#end}

You can use the same principal to turn on or off complex textures, or to hide slow isosurfaces.

The possibilities are endless...

Tip 7 Place By Pattern

2006-02-07T00:42:00.000-08:00

A trick that can be used to place objects in a scene is to use "place by pattern". This sort of thing can be used for placing trees across a landscape, or spaceships in space.

I thinh to keep in mind is that all POV-Ray patterns are 3D, you just normally see tem in 2D as it is plastered across various objects. So the theory is we can chack the value of a pettern at any point in the 3D coordinate system.

The scene below was my first experiment in place by pattern and demonstrates it quite nicely. Note : the Green and White plane is only for reference so that you can "see" the pattern being tested. The scene does not test the texture on the plane, but it does use the same pattern.

#include "colors.inc"
#include "functions.inc"
camera { location <0,> look_at <0,> }
light_source {<-200, 1000, -400> White}

// a scaling value for the pattern
#declare patternScale = 10;

// a plane to show the pattern being used to place the objects
plane {y, -.00001 texture {
pigment {agate scale patternScale pigment_map { [0 White] [.8 White] [1 Green]}}}}

// testing an area in the x-z plane from -40 to +40 for both co-ords, so set up
// two loops one for X and one for z. We will test every .5 units
#declare myx = -40;
#while(myx<=40)
#declare myz = -40;
#while(myz <= 40)
// This if tests the value returned by the pattern function. Note that
// pattern functions return a value between 0 and 1 ( the value of the pigment map)
#if(f_agate(myx/patternScale,0,myz/patternScale) > .95)
// ... and puts in a red sphere , 2 units above the plane, if the value is over .95
sphere {,.2 texture { pigment {Red }}}
#end
#declare myz = myz +.5;
#end
#declare myx=myx+.5;
#end

Tip 6 Create Loads of Objects

2006-02-06T00:43:00.000-08:00

Sometimes when you want to put a lot of objects in a scenesuch as tiles on a wall, you can copy your single tileover and over again and manually edit the co-ordinates of each. But man oh man, thats a lot of work.

POV-Ray gives us a much better way, and thats the "#while"statement. Render the following...

#include "colors.inc"
camera {location <-4,4,-5>look_at <0,0,>}
light_source{<-50, 100, -50> color White }
background { color <0.25,0.35,0.80> }
plane {y, -1 pigment { color rgb <0.7,0.5,0.3>}}
#declare xpos = -10;
#while(xpos <> box { <0,1,0>,<.9,0,.2> texture { pigment { Red } } translate }
#declare xpos = xpos+1;
#end

The bottom half of this scene is the clever bit. "#while" is a programing loop, that in this case produces 20 boxes in a line.

This little loop saves you having to manually create 20 boxes and edit the position of each. If your want to know how all this stuff works you need to read the Help relating to "#while" but heres the basics.

This SDL uses xpos to translate each box into position. The "#while" moves the value of xpos from -10 up to 10. And for each value of xpos, it creates a "box".

You can Nest "#while" loops ( Thats putting one #while inside another ) which means you can quickly build up vast numbers of objects for very little typing. Render the following to see even more boxes.

#include "colors.inc"
camera {location <-4,4,-5>
look_at <0,0,0>}
light_source{<-50, 100, -50> color White }
background { color <0.25,0.35,0.80> }
plane {y, -1 pigment { color rgb <0.7,0.5,0.3>}}
#declare xpos = -10;
#while(xpos <>
#declare zpos = 0;
#while(zpos < 10)
box { <0,1,0>,<.9,0,.2> texture { pigment { Red } } translate }
#declare zpos = zpos+1;
#end
#declare xpos = xpos+1;
#end

Tip 5 Rending Sizes

2006-02-03T01:57:00.000-08:00

Sometimes you need to render an image at a non-standard image size. For instance you might want a really small image say, 25 by 25 pixels or a short but wide image 800 by 120. You could spend a lot of time moving cameras and rendering huge scenes that you only want to see a part of, but there is an easier way.

If you look in the following folder on your machine...

C:\Program Files\POV-Ray for Windows v3.6\renderer

... you'll see a file called "quickres.ini". This file has a list of all of the standard rendering sizes.

Add the following snippet ( the text between the hashes but not the hashes)
########################

[25x25, No AA]
Width=25
Height=25
Antialias=Off

[800x120, No AA]
Width=800
Height=120
Antialias=Off

[25x25, AA 0.3]
Width=25
Height=25
Antialias=On
Antialias_Threshold=0.3

[800x120, AA 0.3]
Width=800
Height=120
Antialias=On
Antialias_Threshold=0.3

#########################

Save the file. You have just added four new options to the standard list of rendering sizes, start POV-Ray and have a look.

Now its worth noting that when you change the width/height ratio of these render sizes it usually becomes neccesary to also alter the camera. If you dont change the camera you get some very distorted images.

I've included a sample camera setting below that I use when rendering the 800 by 120 image. The "up" and "right" are a bit of a mystery to me at the moment ( I really must Read The Flippin Manual), but they appear to specify relative perspective ratios.

Now if that sounds like gobbeldegook, I'm sorry. But you'll see the effects easier than I can explain them. Render an 800 by 120 image without the "up" and "right", and then again with them, you'll see whats going on.

It would also be worth trying a few more renders and fiddeling with the numbers!!!

I should also note that when rendering the 25 by 25 images it wasn't neccessary to change the camera settings.

camera { perspective location <0,0,-4> look_at <0,0,0> up<0,.35,0> right<2.33,0,0> }

Tip 4 Macro's

2006-02-02T00:43:00.000-08:00

Tip 4 : Macros, use 'em! I use macros extensively. The reasonis straight forward, I find they save me time. They allow meto alter things between renders from a single place.
For instance. If I'm modeling a Window, I'll make a macro with the ability to set how much the window is open.

Below is a simple scene that uses a macro. Read on and I'll explain all...

#include "colors.inc"
camera {location <-1,3,-5>
look_at <0,0,0>}
light_source {<-50, 100, -50> color White}
background { color <0.25,0.35,0.80>}
plane {y,-1 pigment{color rgb <0.7,0.5,0.3>}}

#macro getShape(tubeLength,ballSize)
union {
cylinder { <(tubeLength/2)*-1,0,0>, ,.2 }
sphere { <0,0,0>,ballSize }
texture { pigment { Red } }
}
#end

object { getShape(2,.5) }
object { getShape(8,.5) translate <0,0,5>}
object { getShape(4,1.5) translate <0,0,10>}

Render the scene, you see three objects that are all variations ona theme. Each of those objects is displayed via the macro which is being called from the "object" lines at the bottom.

The macro is begins with "#macro" and ends with "#end".

If you rendered the scene youll see the shape varies cylinder lengthand sphere size.

The "object" definitions at the bottom each pass differn't length and size numbers to the macro. This means I can easily generate multiple versions of the same shape.

How do I use this capability in real scenes?

Often when trying to get a scene just-right, you want to tinker with various positions ofobjects, or object sizes, or even textures.

A Door macro could alter the angle at which the door is ajar.
A Wheel macro could define the amount of air in the tyre.
A Pen macro could define the ink colour.
A Roman Column macro could define the column height.
A Light macro could define the "fade_distance" of the "light_source".

A macro can contain just about any SDL code, it does not have to return just one object, such as the union in the example above. It can also call other "object"s that are themselves macros.

It's a cool feature of SDL and worth considering, when you start your next scene.

Tip 3 Your own Scene Templates

2006-02-01T00:38:00.000-08:00

Here's another installment of my POV life. I havn't just discovered this or anything, but its a good tip that all POVvers should know.

Tip 3 : If like me you start a large number of scenes, you really dont want to be typing in the basic stuff like [ #include "colors.inc"] every time. That would be real boring. So you may already have discovered the "Insert" menu, and even the Scene Templates there.

Well, I never liked any of those scene templates, they all seem to contain a whole bunch of comments that I dont need or want. Or have wacky camera settings. Me, I like a background color, a plane, a point light, a camera looking at <0,0,0> and a couple of includes in my fresh scenes. So, whats the tip...

Create your own scene template(s). This simply a "txt" file that you can create with notepad. Then copy the "txt" file into ...

C:\Program Files\POV-Ray for Windows v3.6\Insert Menu\00 - Scene templates

A new option will then appear on the "insert / scene templates" menu. The name of the menu item will match the name of your file.

Here's one of my template files...

#include "colors.inc"
#include "shapes.inc"
camera { location <0,1,-5> look_at <0,>}
light_source { <-50, 100, -50> color White }
background { color <0.25,0.35,0.80> }
plane { y, -1 pigment { color rgb <0.7,0.5,0.3> }}

Getting Started... Tips 1 & 2

2006-01-31T05:40:00.000-08:00

Hi, I'm just starting this POV-Ray blog so that I can share any scene tips and useability features I discover during my ongoing love affair with POV-Ray.

Tip 1 : Use POV-Ray, its free, which is the only qualifier you need.

Tip 2: Stick "http://news.povray.org/" into your browser and scoot on over to the news groups. The commune over there is active and extreemly helpful. Props to the server host for just being great!