//attribute float gl_Vertex;          // Sprite center world position
//attribute float gl_MultiTexCoord0;  // Luminosity
//attribute vec2  gl_Color;           // Color index, vertex id

uniform sampler1D ColorMap;
uniform sampler2D Texture;
uniform vec4      Param;
uniform mat4x4    oldModelViewMatrix;

#ifdef _VERTEX_

out vec3 TexCoord;
out vec3 ColBright;

void main()
{
       TexCoord.x = mod(floor(gl_Color.y * 4.0), 2.0);
       TexCoord.y = mod(floor(gl_Color.y * 2.0), 2.0);

       vec4 viewPosN = gl_ModelViewMatrix * gl_Vertex;
       vec4 viewPosO = oldModelViewMatrix * gl_Vertex;
       vec4 viewPos;
       if (TexCoord.x == 0.0) viewPos = viewPosN;
       else                   viewPos = viewPosO;

       float Dist2 = dot(viewPos.xyz, viewPos.xyz);
       float mag = Param.x * exp(gl_MultiTexCoord0.x) / Dist2;

       ColBright.x = gl_Color.x;
       ColBright.y = clamp(Param.w*(mag - Param.y), 0.0, 1.0);
       ColBright.z = mag;

       if (mag > 1.0)  mag = 1.0 + log(mag);
       float spriteSize = Param.z * sqrt(Dist2 * mag);

       vec2 Offset = 1.0 - TexCoord.xy * 2.0;
       vec3 Ray = viewPosN.xyz - viewPosO.xyz;

       //if ((dot(Ray, Ray) <= 1e-6) || (abs(viewPosN.z - viewPosO.z) <= 1e-4))
       if (dot(Ray, Ray) <= 1e-6)
       {
           viewPos.xy += Offset * spriteSize;
           TexCoord.z = 0.0;
       }
       else
       {
           //float RayLen = 0.5 * length(viewPosN.xy - viewPosO.xy) / ((1.0 + abs(viewPosN.z - viewPosO.z)) * spriteSize);
           float RayLen = 0.5 * length(viewPosN.xy - viewPosO.xy);

           spriteSize /= RayLen + 1.0;
           //spriteSize /= RayLen*RayLen + 1.0;
           TexCoord.z = RayLen / (RayLen + 1.0);

           /*if (dot(Ray, viewPosN.xyz) <= 1e-3)
           {
               viewPos.xy += Offset * spriteSize;
               TexCoord.z = 0.0;
           }
           else*/
           {
               vec3 Tangent = normalize(cross(Ray, viewPosN.xyz));
               mat2x2 Mat = mat2x2(Tangent.y, -Tangent.x, Tangent.x, Tangent.y);
               viewPos.xy += (Mat * Offset) * spriteSize;
           }
       }

       gl_Position = gl_ProjectionMatrix * viewPos;
}

#else

in vec3 TexCoord;
in vec3 ColBright;

void main()
{
       vec2 texCoord;
       texCoord.y = TexCoord.y;
       if (abs(2.0 * TexCoord.x - 1.0) < TexCoord.z)
           texCoord.x = 0.5;
       else
       {
           if (TexCoord.x > 0.5)
               texCoord.x = (TexCoord.x - TexCoord.z) / (1.0 - TexCoord.z);
           else
               texCoord.x = TexCoord.x / (1.0 - TexCoord.z);
       }

       vec4 Color = texture1D(ColorMap, ColBright.x);

       //////////////////////
       // new code nere //
       //////////////////////

       float DesaturateThreshold = 2.0;
       float Gray = dot(Color.rgb, vec3(0.3, 0.59, 0.11));
       Color.rgb = mix(vec3(Gray), Color.rgb, pow(clamp(ColBright.z / DesaturateThreshold, 0.0, 1.0), 3));

       ////////////////////////
       // end of new code //
       ////////////////////////

       gl_FragColor.rgb = ColBright.y * Color.rgb * texture2D(Texture, texCoord).rgb;
       //gl_FragColor.a = ColBright.y;
       gl_FragColor.a = 0.0;
}

#endif