This is the Mind Melter running on my XBox 360, I didn’t have to touch a single line of code to get it working!

The little dirchie at the top of the screen is me manipulating the colour palette for the plasma texture with the 360 controler.

Still can’t wait to see it on Matt’s big 50inch Plasma TV.

Tonights coding efforts have born much fruit, I managed to finally generate a decent texture to use for base of the shockwave effect and roughly impliment the effect in game.

The in game result is as good as I’d hope, it still needs a thumping sound effect to give it real punch but I think I’m on to a winner.

The first trick to the effect is trying to get your head around the base texture (to the right), I’ve used a the same technique they use for bump and nornal mapping, where the texture map doesn’t hold colour information it stores offsets for the sampling co-ordinates of the background texture.

Red from 0 to 255 stores the X axis offset and Green the Y, the baby poo tan/green in the middle and the outside on the texture is Colour R128 G128 B0 A255 right in the middle, in other words no offset.

First up I tried using photoshop to generate the texture with overlapping gradients, but I couldn’t get the results I was after so I ended up using XNA to generate the texture on screen and saved it out with the handy Save() method of Texture2D.

Here’s the shader I use to apply the offset texture to the back ground texture:

uniform extern float4x4 World : WORLD;
uniform extern float4x4 ViewProj : VIEWPROJECTION;
uniform extern texture backGroundTexture;
uniform extern texture offsetTexture;
uniform extern float textureOffset;


struct VS_OUTPUT
{
    float4 position : POSITION0;
    float4 textureCoordinate : TEXCOORD0;
    float4 P : TEXCOORD1;
};

sampler backGroundSampler = sampler_state
{
    Texture = ;
    MIPFILTER = LINEAR;
    MINFILTER = LINEAR;
    MAGFILTER = LINEAR;    
};

sampler offsetSampler = sampler_state
{
    Texture = ;
    mipfilter = LINEAR;      
};

VS_OUTPUT Transform(
    float4 Pos  : POSITION, 
    float4 Col : COLOR,
    float4 TextureCoordinate : TEXCOORD0
    )
{
    VS_OUTPUT Out = (VS_OUTPUT)0;

    Out.position = mul(Pos, mul(World, ViewProj));
	Out.textureCoordinate = TextureCoordinate; 
	Out.P = Col;

    return Out;
}

float4 ApplyTexture(float2 textureCoordinate : TEXCOORD0, float4 p : TEXCOORD1) : COLOR
{
	float4 bump = tex2D(offsetSampler, textureCoordinate);
	
	float2 perturbation = 0.5f - bump.rg;

	float2 perturbatedTexCoords = textureCoordinate + perturbation / 25.0; // modify this division value for more or less effect

	float4 c = tex2D(backGroundSampler, perturbatedTexCoords);

    return c;
}

technique TransformTechnique
{
    pass P0
    {
        vertexShader = compile vs_1_1 Transform();
        pixelShader  = compile ps_2_0 ApplyTexture();

    }
}