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OB - Brick shader by MrDutchy
//
// Vertex shader for procedural bricks
//
// Authors: Dave Baldwin, Steve Koren, Randi Rost
//          based on a shader by Darwyn Peachey
//
// Copyright (c) 2002-2004 3Dlabs Inc. Ltd. 
//
// See 3Dlabs-License.txt for license information
//

uniform vec3 LightPosition;

const float SpecularContribution = 0.3;
const float DiffuseContribution  = 1.0 - SpecularContribution;

varying float LightIntensity;
varying vec2  MCposition;

void main(void)
{
    vec3 ecPosition = vec3 (gl_ModelViewMatrix * gl_Vertex);
    vec3 tnorm      = normalize(gl_NormalMatrix * gl_Normal);
    vec3 lightVec   = normalize(LightPosition - ecPosition);
    vec3 reflectVec = reflect(-lightVec, tnorm);
    vec3 viewVec    = normalize(-ecPosition);
    float diffuse   = max(dot(lightVec, tnorm), 0.0);
    float spec      = 0.0;

    if (diffuse > 0.0)
    {
        spec = max(dot(reflectVec, viewVec), 0.0);
        spec = pow(spec, 16.0);
    }

    LightIntensity  = DiffuseContribution * diffuse +
                      SpecularContribution * spec;

    MCposition      = gl_Vertex.xy;
    gl_Position     = ftransform();
}

//
// Fragment shader for procedural bricks
//
// Authors: Dave Baldwin, Steve Koren, Randi Rost
//          based on a shader by Darwyn Peachey
//
// Copyright (c) 2002-2004 3Dlabs Inc. Ltd. 
//
// See 3Dlabs-License.txt for license information
//

uniform vec3  BrickColor, MortarColor;
uniform vec2  BrickSize;
uniform vec2  BrickPct;

varying vec2  MCposition;
varying float LightIntensity;

void main(void)
{
    vec3  color;
    vec2  position, useBrick;
    
    position = MCposition / BrickSize;

    if (fract(position.y * 0.5) > 0.5)
        position.x += 0.5;

    position = fract(position);

    useBrick = step(position, BrickPct);

    color  = mix(MortarColor, BrickColor, useBrick.x * useBrick.y);
    color *= LightIntensity;
    gl_FragColor = vec4 (color, 1.0);
}