Part III in Visual Studio .NET

Generator QR Code in Visual Studio .NET Part III

ColorArg2[0] AlphaOp[0] ColorOp[1] AlphaOp[1]

= = = =

DIFFUSE; DISABLE; DISABLE; DISABLE;

} pass PGlow { // glow shader VertexShader = compile vs_1_1 VSGlow(); PixelShader = NULL; // no texture Texture[0] = NULL; // enable alpha blending AlphaBlendEnable = TRUE; SrcBlend = ONE; DestBlend = ONE; // set up texture stage states to use the diffuse color ColorOp[0] = SELECTARG2; ColorArg2[0] = DIFFUSE; AlphaOp[0] = SELECTARG2; AlphaArg2[0] = DIFFUSE; ColorOp[1] = DISABLE; AlphaOp[1] = DISABLE; } } technique TGlowOnly { pass PGlow { // glow shader VertexShader = compile vs_1_1 VSGlow(); PixelShader = NULL; // no texture Texture[0] = NULL; // enable alpha blending AlphaBlendEnable = TRUE; SrcBlend = ONE; DestBlend = ONE; // set up texture stage states to use the diffuse color ColorOp[0] = SELECTARG2; ColorArg2[0] = DIFFUSE;

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AlphaOp[0] AlphaArg2[0] ColorOp[1] AlphaOp[1] } }

= = = =

SELECTARG2; DIFFUSE; DISABLE; DISABLE;

The glow shader and the texture shader have already been discussed in detail. To see the explanation of the HLSL shader code, view the Glow example in 8. The interesting part of this example in this chapter is the effect code, so we can skip over the global variables, the VSTexture shader, and the VSGlow shader all the way down to the techniques to see how to design a technique that uses more than one vertex shader. The first technique, TGlowAndTexture, contains two passes: PGlow and PTexture. It s arranged like this:

technique TGlowAndTexture { pass PTexture { // shader objects ... ... // texture objects ... // effect state ... } pass PGlow { // shader objects ... // texture objects ... // effect state ... } }

We can almost guess what s going to happen just by reading the names of the techniques and passes. The pass named PTexture will draw a solid textured object, and the pass named PGlow will draw a glow object. By setting the TGlowandTexture technique during render, one of the following three things can happen:

pass PTexture { VertexShader = compile vs_1_1 VSTexture(); PixelShader = NULL; // texture Texture[0] = (Tex0); // sampler states MinFilter[0] = LINEAR; MagFilter[0] = LINEAR; MipFilter[0] = LINEAR; // set up texture stage states for single texture modulated by diffuse ColorOp[0] = MODULATE; ColorArg1[0] = TEXTURE; ColorArg2[0] = DIFFUSE; AlphaOp[0] = DISABLE; ColorOp[1] = DISABLE; AlphaOp[1] = DISABLE; }

The PTexture pass does three things:

Creates a vertex shader object by compiling the VSTexture function. This shader passes texture coordinates to the pipeline to enable the pixel shader to perform texture sampling. Binds the texture in Tex0 to the sampler s0. Texture sampler s0 is specified as Texture[0]. If we wanted to specify sampler s1, we would have specified Texture[1] instead. The index number corresponds to the sampler number. Initializes the multitexture blender. Because this example contains no pixel shader, the texture blending is done with the multitexture blender. The first stage is set up to blend the diffuse color with the texture sample. The second stage is disabled.

The other pass, PGlow, applies the glow. Here s the effect state that must be set to apply the glow:

pass PGlow { // glow shader VertexShader = compile vs_1_1 VSGlow(); PixelShader = NULL;

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// no texture Texture[0] = NULL; // enable alpha blending AlphaBlendEnable = TRUE; SrcBlend = ONE; DestBlend = ONE; // set up texture stage states to use the diffuse color ColorOp[0] = SELECTARG2; ColorArg2[0] = DIFFUSE; AlphaOp[0] = SELECTARG2; AlphaArg2[0] = DIFFUSE; ColorOp[1] = DISABLE; AlphaOp[1] = DISABLE; }

The Glow pass does four things:

Creates a vertex shader object by compiling the VSGlow function. This shader perturbs the position data in the direction of a vertex normal to generate the glow position. It also implements a glow color function that s relative to the camera and is greatest where the vertex normals are nearly at a right angle to the view direction (a vector from the camera to the object). If this is not clear, revisit the Glow sample in 8 for more detail. Disables the multitexture blender. By setting the first texture stage to NULL (with Texture[0] = NULL;), the multitexture blender is disabled. Enables alpha blending in the frame buffer. The solid textured object is in the frame buffer. Alpha blending is used to blend the semitransparent glow color with the texture color. The blending equation is configured by setting the blending render states, SrcBlend and DestBlend. Initializes the multitexture blender. The multitexture blender simply passes the glow color on to the first stage. The second stage is disabled.

The second technique in the effect named TGlowOnly draws the glow. There s no solid textured object; there s only the semitransparent glow. Here s the technique: