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OpenGL (1.2 - 2.0) Code Samples - Page 13
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Solid Node BSP
Tree Compiler |
| One method of speeding up a
game engine is to use a BSP-Tree (Binary-Space
Partitioning Tree) to subdivide and sort
your game's world geometry.
This is done by dividing up, sorting,
and storing polys in a BSP Tree in a such
as way as to denote their relationship to
one another (i.e. being in front of or in
back of another poly). Once the BSP tree
is compiled or built, the engine can quickly
decide whether or not it should render certain
polys based on the view’s current location
within the world.
For example, the BSP compiler in this
sample demonstrates how early game programmers,
who didn't have hardware accelerated z-buffers,
used a simple solid-node style BSP tree
to sort their scene polys into a back-to-front
order for proper rendering. The sample also
demonstrates how a BSP Tree can be used
for collision detection by identifying whether
or not a unobstructed line-of sight can
be established between two 3D points.
Unfortunately, the code doesn't go into
a lot of BSP Tree theory or teach the basics,
so if you're new to the concept of a BSP
Tree, check out this cool little
Java Applet for a real-time demonstration
of how they work.
This sample is based on one of the BSP
demos that came with the
"Advanced 3D BSP, PVS and CSG Techniques"
course offered at
GameInstitute.com. If you're truly interested
in learning about BSP trees and how they're
used in games, this course is the best by
far and I highly recommend it.
Check out the DirectX9
source code page for the Direct3D equivalent
of this sample.
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Simple Introduction to
the NovodeX Physics SDK |
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This sample demonstrates how to use the
NovodeX
Physics SDK by simply creating and dropping
boxes on to a plane that represents the
ground. Check out the
DirectX9 source
code page for the Direct3D equivalent of
this sample.
Relevant Keywords: NxPhysicsSDK, NxScene,
NxVec3, ErrorStream, NxCreatePhysicsSDK,
setMaterialAtIndex, createScene, shapes.pushBack,
createActor, NX_BROADPHASE_COHERENT, release,
releaseScene, NxBodyDesc, NxBoxShapeDesc,
NxActorDesc, createActor, userData, getNbActors,
getActors, getGlobalPose, getColumnMajor44,
flushStream, and fetchResults.
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How to use
the Tokamak SDK to Create a Rope or Chain
using Ball-Joints |
| This sample demonstrates how
to use the
Tokamak Physics SDK to create a chain
or rope like object by using small collision
cubes joined by ball-joints. For demonstration
purposes, the chain is dropped onto a platform,
which doesn’t quite catch all of it. This
allows the chain to hang off and swing about.
For fun, you can use the F1 key to lift
up on the chain's last segment by applying
some velocity to it. Check out the
DirectX9 source
code page for the Direct3D equivalent of
this sample.
Relevant Keywords: neSimulator, neRigidBody,
neAnimatedBody, neSimulatorSizeInfo, neBoxInertiaTensor,
neJoint, neGeometry, CreateSimulator, CreateRigidBody,
AddGeometry, SetBoxSize, CollideConnected,
UpdateBoundingInfo, SetInertiaTensor, SetMass,
SetJointFrameWorld, SetType, SetEpsilon,
SetIteration, Enable, and GetTransform.
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How to
use the Tokamak SDK to Create a Stack of
Blocks
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This sample demonstrates how to use the
Tokamak Physics SDK to create a stack
of blocks which can be knocked over. For
demonstration purposes, you can use the
F1 key to lift up and drop the bottom block,
which will obviously disturb the stack.
You can also use the F2 key to tilt the
blue platform and dump the blocks over the
side. Check out the
DirectX9 source code page for the Direct3D
equivalent of this sample.
Relevant Keywords: neSimulator, neRigidBody,
neAnimatedBody, neSimulatorSizeInfo, neBoxInertiaTensor,
neJoint, neGeometry, CreateSimulator, CreateRigidBody,
AddGeometry, SetBoxSize, UpdateBoundingInfo,
SetInertiaTensor, SetMass, Enable, SetRotation
and GetTransform.
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Multi-Texture Blending With Cg |
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This sample demonstrates how to
use a Cg fragment shader to blend three
textures together by passing the desired
contribution of each texture into the
shader via the vertex's color.
Techniques like this are becoming very
popular in terrain rendering engines
which need to blend dramatically
different textures such as rock and
grass together with out creating a
noticeable edge. For example, with three
textures consisting of stone, grass, and
sand you can render a mountain that
blends in patches of grass and sand at
its base.
Relevant Keywords: glActiveTextureARB,
glMultiTexCoord2fARB,
glClientActiveTextureARB, cgGLIsProfileSupported,
cgCreateContext, cgCreateProgramFromFile,
cgGLLoadProgram, cgGetNamedParameter, cgGLSetStateMatrixParameter,
cgGLSetParameter4fv, cgGLBindProgram, cgGLEnableProfile,
cgGLDisableProfile, cgDestroyProgram, cgDestroyContext,
cgGLSetTextureParameter,
cgGLDisableTextureParameter, CGprofile, CGcontext, CGprogram, CGparameter,
CG_PROFILE_ARBFP1, CG_PROFILE_FP30,
CG_PROFILE_FP20, CG_SOURCE, CG_GL_MODELVIEW_PROJECTION_MATRIX,
CG_GL_MATRIX_IDENTITY, GL_TEXTURE0_ARB,
GL_TEXTURE1_ARB, GL_TEXTURE2_ARB, POSITION, COLOR0,
main, float4, float3, uniform, float4x4, mul, in, and out.
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