Normal mapping for Codea

-- normal maping

function setup()
    m = mesh()
    m.shader = shader("Documents:NormalMaping")
    m.shader.Resolution = vec2(1.0,1.0)
    m.shader.LightPos = vec3(0,0,0.075)
    m.shader.LightColor = vec4(0.94,0.77,0.17,2.0)
    m.shader.AmbientColor = vec4(0.6,0.6,1.0,0.5)
    m.shader.Falloff = vec3(0.4,2.0,10.0)
    m.shader.s_multitex = "Dropbox:bricks_indented_texture_9181161_NRM" --rgb normal map
    m.shader.tex = "Dropbox:bricks_indented_texture_9181161_COLOR" --color map
    m:addRect(300,300,1000,1000)
    tchx=0
    tchy=0
end


function draw()
    m.shader.LightPos = vec3(tchx/WIDTH,tchy/HEIGHT,0.075)
    m:draw()
end

function touched(touch)
    if touch.state == BEGAN
    or touch.state == MOVING then
        tchx=touch.x+50
        tchy=touch.y+50
    end
end



[[[[[[[[[[[[Shader]]]]]]]]]]]]]]]

--------vertex shader---------

attribute vec4 position;
attribute vec4 color;
attribute vec2 texCoord;

varying vec2 vTexCoord;
varying vec4 vColor;

uniform sampler2D s_multitex;

uniform mat4 modelViewProjection;

void main()
{
    vec4 object_space_pos = vec4(position.x,position.y,position.z,1.0);
    gl_Position = modelViewProjection * position;

    vColor = color;
    vTexCoord = texCoord;
}



---------Fragment shader------------

//Default precision qualifier
precision highp float;

varying vec2 vTexCoord;
varying vec4 vColor;

uniform sampler2D tex;

uniform lowp sampler2D s_multitex;

uniform vec2 Resolution;
uniform vec3 LightPos;
uniform vec4 LightColor;
uniform vec4 AmbientColor;
uniform vec3 Falloff;

void main()
{
    vec4 DiffuseColor = texture2D(tex,vTexCoord);
    vec3 NormalMap = texture2D(s_multitex,vTexCoord).rgb;
    NormalMap.g = 1.0 - NormalMap.g;
    vec3 LightDir = vec3(LightPos.xy-(vTexCoord.xy/Resolution.xy),LightPos.z);
    LightDir.x *= Resolution.x/Resolution.y;
    float D = length(LightDir);
    vec3 N = normalize(NormalMap*2.0-1.0);
    vec3 L = normalize(LightDir);
    vec3 Diffuse = (LightColor.rgb * LightColor.a) * max(dot(N,L), 0.0);
    vec3 Ambient = AmbientColor.rgb * AmbientColor.a;
    float Attenuation = 1.0 / (Falloff.x + (Falloff.y*D) + (Falloff.z*D*D));
    vec3 Intensity = Ambient + Diffuse * Attenuation;
    vec3 FinalColor = DiffuseColor.rgb * Intensity;
    gl_FragColor = vColor * vec4(FinalColor,DiffuseColor.a);
}