// part of the Irrlicht Engine Shader example.
// These simple Direct3D9 pixel and vertex shaders will be loaded by the shaders
// example. Please note that these example shaders don't do anything really useful. 
// They only demonstrate that shaders can be used in Irrlicht.

//-----------------------------------------------------------------------------
// Global variables
//-----------------------------------------------------------------------------
float4x4 mWorldViewProj;  // World * View * Projection transformation
float4x4 mInvWorld;       // Inverted world matrix
float4x4 mTransWorld;     // Transposed world matrix
float3 mLightPos;         // Light position
float4 mLightColor;       // Light color


// Vertex shader output structure
struct VS_OUTPUT
{
	float4 Position   : POSITION;   // vertex position 
	float4 Diffuse    : COLOR0;     // vertex diffuse color
	float2 TexCoord   : TEXCOORD0;  // tex coords
};


VS_OUTPUT vertexMain( in float4 vPosition : POSITION,
                      in float3 vNormal   : NORMAL,
                      float2 texCoord     : TEXCOORD0 )
{
	VS_OUTPUT Output;

	// transform position to clip space 
	Output.Position = mul(vPosition, mWorldViewProj);
	
	// transform normal 
	float3 normal = mul(vNormal, mInvWorld);
	
	// renormalize normal 
	normal = normalize(normal);
	
	// position in world coodinates
	float3 worldpos = mul(mTransWorld, vPosition);
	
	// calculate light vector, vtxpos - lightpos
	float3 lightVector = worldpos - mLightPos;
	
	// normalize light vector 
	lightVector = normalize(lightVector);
	
	// calculate light color 
	float3 tmp = dot(-lightVector, normal);
	tmp = lit(tmp.x, tmp.y, 1.0);
	
	tmp = mLightColor * tmp.y;
	Output.Diffuse = float4(tmp.x, tmp.y, tmp.z, 0);
	Output.TexCoord = texCoord;
	
	return Output;
}



// Pixel shader output structure
struct PS_OUTPUT
{
    float4 RGBColor : COLOR0;  // Pixel color    
};


sampler2D tex0;
	
PS_OUTPUT pixelMain( float2 TexCoord : TEXCOORD0,
                     float4 Position : POSITION,
                     float4 Diffuse  : COLOR0 ) 
{ 
	PS_OUTPUT Output;

	float4 col = tex2D( tex0, TexCoord );  // sample color map
	
	// multiply with diffuse and do other senseless operations
	Output.RGBColor = Diffuse * col;
	Output.RGBColor *= 4.0;

	return Output;
}

                    "!!ARBvp1.0\n"
                    "OPTION ARB_position_invariant;"
                    "PARAM c0 = { 0, 0, 0, 0 };"
                    "TEMP R0, R1;"
                    "ATTRIB v18 = vertex.normal;"
                    "PARAM s18 = state.light[" << _lightnum << "].position;"
                    "PARAM s16 = state.light[" << _lightnum << "].diffuse;"
                    "PARAM s1 = state.material.diffuse;"
                    "PARAM s631[4] = { state.matrix.modelview.invtrans };"
                    "MOV R0, s1;"
                    "MUL result.color.front.primary, R0, s16;"
                    "DP4 R0.x, s18, s18;"
                    "RSQ R0.x, R0.x;"
                    "MUL R1, R0.x, s18;"
                    "DP4 R0.x, s631[0], v18;"
                    "DP4 R0.y, s631[1], v18;"
                    "DP4 R0.z, s631[2], v18;"
                    "DP4 R0.w, s631[3], v18;"
                    "DP4 R0.x, R1, R0;"
                    "MAX result.texcoord[0].x, c0.x, R0.x;"
                    "END";