A word about the shader files:

The shaders that effect this model are stored in the files:

• DefaultEffects.fx    -- contains the techniques and shaders that perform per vertex and per pixel lighting on the model.


• common_Functions.fxh -- contains common routines that are called from the shaders in DefaultEffects.fx.


• ViewingTangentSpace.fx -- contains the shaders for viewing the tangent space.


• LightEffects.fx -- contains shaders for viewing the light source.


• MiscEffects.fx -- contains miscellaneous shaders. Currently only the menu shaders exist in this file.

All the cool effects are in DefaultEffects.fx.  The techniques are at the bottom of the file.  They pass in uniform values into the different shaders.  These uniform values tell the compiler that these parameters are constant for this technique.  This allows the compiler to perform dead code removal and optimize the shaders for us.

Feel free to add new shaders or new techniques.  You can add them without having to recompile the app.  You can write you shaders into DefaultEffects.fx and hit the "r" key to reload the shader files.  If you add new techniques, you will see them automatically added into the help menu.

Matrix Skinning:

Matrix Skinning is the act of animating a vertex over time given a known set of matrices and a known set of blend weights assigned to those matrices.  The model shown here has 39 bones and an animation cycle of 13 frames.

Each frame the application re-computes the blending matrices for each vertex by linearly interpolating between the matrices needed for the two frames the animation is currently between.  So, if, based on time, the app is asked to render the model as if it were at frame 9.75 it would blend the matrices for frame 9 and frame 10 in the app before passing these matrices to the vertex shader.

The skinning happens as part of the vertex shader and is defined in two functions in common_Functions.fxh.:

• SkinPoint(...) -- this function skins a vertex (float 4) by the four skinning matrices.


• SkinVector( ... ) -- this function skins a vector (float 3) by the four skinning matrices.

Bump Mapping:

This application also shows how to compute tangent space from a models vertex position, normal, and texture coordinates.  The tangent space is passed into vertex shader as part of the vertex stream.  For more information on the form of tangent space computation we used, see Game Programming Gems, 2000, Charles River Media, ISBN-1-58450-049-2.

The vertex shader transforms the tangent space vectors into world space and passes them down to the pixel shader.

The pixel shader takes the tangent space vectors and uses them as a basis to transform the normal read in from the bump map into world space.  This allows us to perform our N dot L computation in world space to achieve bump mapping.

VertexBlend Controls:

• Left Drag to rotate object
• Right Drag to translate object in plane of screen
• Middle Drag to translate object perpendicular to screen
• [A] - Toggles animation.
• [W] - Toggles viewing wire frame.
• [T] - Toggles viewing tangent space.
• [D] - Dumps a screen shot.
• [R] - Reloads shaders.
• [+/-] - Increases or decreases animation speed.
• [I/M] - Increases or decreases Depth Bias (for wire frame).
• [O/J] - Increases or decreases Z Slope Scale (for wire frame).
• Up/Down Arrows - Previous/Next Shader.
• Alt+[ENTER] - Toggles between fullscreen and windowed modes .
• [TAB] - Next Object.
• [SPACE] - Toggles help menu.
• [ESC] - Quit

Requirements

• Radeon 9700 series products
• DirectX runtime