From 356f94fc355f36c16e48555d10c2377dff4b7554 Mon Sep 17 00:00:00 2001 From: Travis CI Date: Tue, 17 Mar 2015 22:38:45 +0000 Subject: Gem 096ed6ef786b7a9d6e11a437ff8526619c89a1fd osx/x86_64 built 'coverity_scan:096ed6ef786b7a9d6e11a437ff8526619c89a1fd' for osx/x86_64 --- Gem/manual/Lighting.html | 107 ----------------------------------------------- 1 file changed, 107 deletions(-) delete mode 100644 Gem/manual/Lighting.html (limited to 'Gem/manual/Lighting.html') diff --git a/Gem/manual/Lighting.html b/Gem/manual/Lighting.html deleted file mode 100644 index dcff171..0000000 --- a/Gem/manual/Lighting.html +++ /dev/null @@ -1,107 +0,0 @@ - - - - - - - Lighting - - - -
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-Lighting

-Lighting is an important factor is how we perceive the quality of an image. -For example, without lighting and shading, a sphere would just look like -a circle. GEM provides two types of lights, a local light and world -light. -

OpenGL uses a vertex lighting model. This means that for every -vertex in the scene, the influence of the light is calculated. The -color for the polygon is then modified by the light value of all of the -vertices. This generally produces a very smooth effect, but you will -occasionally run into rendering artifacts, especially if you use local -lights. For example, imagine you have a local light close a large -square. The corners of the square are far away from the light, so -none of them will be lit very brightly, even though the light itself is -very close to the surface of the square. -

It is important to realize that lighting is an expensive operation to -use. The number of polygons that you will be able to render will -be much lower if lighting is turned on. As usual, the complexity -of the scene and the speed of your computer and graphics card will greatly -affect your frame rate. -

GEM has only a maximum of 8 lights at one time. If you try to -create more lights than that, you will get an error message. -

Activate lighting -
[world_light] - A directional light -
[light] - A point light in the world -
Moving lights -

-

-Activate lighting

-Lighting is activated by sending a message to [gemwin]. If you -send "lighting 1", then lighting will be turned on. If you send "lighting -0", then lighting will be turned off. The lighting state is kept -even if you destroy the gemwin. This means that if you close a patch -and open another one, the lighting will still be the same. -

Individual lights can be turned on and off by sending a 1 or 0 to the -left inlet of the light object itself. -

-

-[world_light]

-A [world_light] is a light which exists infintely far away. -This reduces the computation needed, so your patch can run faster, but -it means that all of the light rays are parallel. The [world_light] -is good for objects like the sun and other lighting affects. This -means that translating a [world_light] has no effect, although rotation -does. -

The following patch is 03.lighting/01.world_light.pd. -

-

- -

The [world_light] has one extra inlet. The right inlet accepts -three floats to set the color of the light. A [color] object -would do nothing. In this case, the light is being set to purple. -The [world_light] also accepts a debug message. The debug message -turns on and off a graphical representation of the light in the scene. -The [world_light] looks like a cone. The cone shows the direction -that the light is coming from. Remember that the actual position -of the light does not matter, so geos behind the cone will still be lit. -It is the direction of the light that matters. This is why you can -rotate the light. -

-

-[light]

-A [light] object generates a point light in the world. Because -the light is local to the scene, there is more math to generate the effect -of the light on the vertices. However, unlike a [world_light], -you can translate the [light] object. -

Below is the patch 03.lighting/02.light.pd. -

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- -

The [light] object has a right inlet for the color, just light -the [world_light] object. As this patch shows, the light can -be moved around the scene with both [rotate] and [translate] -objects. If you were to set the translate X value equal to 1.0, then -the sphere would not be lit at all. This is because the light would -be inside of the sphere. When you turn on the debug representation, -it is a sphere with its origin where the light it. The [light] -object does not have any size. It exists as a point source. -

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-Moving lights

-The patch 03.lighting/03.controlLights.pd allows you to move a [light] -and [world_light] object in the same scene to see the difference between -the two objects. -

The patch 03.lighting/04.moveSpheres.pd is an example which moves -two spheres around the world. Turn on and off the individual lights -for a demonstration of a local versus infinite light. -

The patch 03.lighting/05.materials.pd uses the material objects to -selectively control the color of the object. Notice that the diffuse object -sets the "overall" color, while the specular objects sets the bright reflective -area where the light directly shines. -

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[return] -
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