Rendering Simple 3D Graphics - Game Development with SlimDX - page 118

You can see that this function contains two blocks of code that are quite similar to
each other. The first one initializes our vertex shader. The downloadable code con-
tains a file called Effects.fx , which is simply a text file containing the code of our
basic shaders.
The first line creates a string variable named vsCompileError . This will receive
any errors that are raised by the next piece of code. As you can see, it is a using
block that calls the ShaderBytecode.CompileFromFile() method to compile
our vertex shader. The returned byte code is the compiled form of our vertex shader.
The CreateFromFile() method takes a handful of parameters, and it also has
several overloads. An overload method is another version of the same function
with a different parameter list.
The first parameter of the CompileFromFile() method is the file containing the
code of the shader we want to compile. The second parameter is the name of the
method in the shader file that contains the code for this shader. The third paramet-
er is the shader model. In this case we used "vs_4_0" , which tells it that we want
to use shader model 4. The fourth parameter is the shader flags we use. We used
ShaderFlags.Debug here. Again, you'd probably want to remove this flag when
your game is done since the debug code will slow down performance. The next two
parameters are a list of shader macros to define during shader compilation and an
interface for handling the include files. These two parameters are set to null as
they are beyond the scope of this chapter. And the final parameter is the psCom-
pileError variable we created above the using block. If there are any errors, they
will be put in this variable.
Inside of this using block we have two lines of code. The first gets the signature for
this shader. Remember that the signature of a shader is just a list of the input and/or
output parameters of that shader. The second line of code creates a VertexShader
object to hold our vertex shader, and stores it in our m_VertexShader variable.
The second block of code in our InitShaders() method is very similar to the first
one. It does the same stuff but for the pixel shader. It compiles our pixel shader and
stores it in our m_PixelShader member variable. You may have noticed that it uses
the same shader file as the vertex shader code at the top of this method. You can
define multiple shaders in a single file, and we've done that here for simplicity.