F//-----------------------------------------------------------------------------
// Name: SphereMap Direct3D Sample
//
// Copyright (c) 1998-2001 Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
Description
===========
The SphereMap sample demonstrates an enviroment-mapping technique called
sphere-mapping. Environment-mapping is a technique in which the environment
surrounding a 3D object (such as the lights, etc.) are put into a texture
map, so that the object can have complex lighting effects without expensive
lighting calculations.
Note that not all cards support all features for all the various environment
mapping techniques (such as cubemapping and projected textures). For more
information on environment mapping, cubemapping, and projected textures,
refer to the DirectX SDK documentation.
Path
====
Source: DXSDK\Samples\Multimedia\D3D\EnvMapping\SphereMap
Executable: DXSDK\Samples\Multimedia\D3D\Bin
User's Guide
============
The following keys are implemented. The dropdown menus can be used for the
same controls.
<Enter> Starts and stops the scene
<Space> Advances the scene by a small increment
<F2> Prompts user to select a new rendering device or display mode
<Alt+Enter> Toggles between fullscreen and windowed modes
<Esc> Exits the app.
Programming Notes
=================
Sphere-mapping uses a precomputed (at model time) texture map which contains
the entire environment as reflected by a chrome sphere. The idea is to
consider each vertex, compute it's normal, find where the normal matches up
on the chrome sphere, and then assign that texture coordinate to the vertex.
The math involves computations for each vertex for every frame. This sample
uses a vertex shader to perform these calculations. Basically, the vertex
shader computes a camera-space reflection vector, given the camera position,
vertex position, and vertex normal. Then, it computes the half-angle vector
between the reflection vector, and the view direction. This vector can then
be scaled and offset by 0.5 to index into the spheremap texture.
This sample makes use of common DirectX code (consisting of helper functions,
etc.) that is shared with other samples on the DirectX SDK. All common
headers and source code can be found in the following directory:
DXSDK\Samples\Multimedia\Common
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