Simple Texture Light

[Brian Beuken]

Here's a simple vertex light shader for you

Code:

  #version 100

  uniform mat4 MVP; // A constant representing the combined model/view/projection matrix.
  uniform mat4 MV;    // A constant representing the combined model/view matrix.
   
  uniform vec4    Ambient; // we will discard this for now, feel free to re add it.
 
  attribute vec2 a_texCoord;
  attribute vec4 a_Position; // Per-vertex position information we will pass in.
  attribute vec3 a_Normal;   // Per-vertex normal information we will pass in.
 
// These will be passed into the fragment shader.
  varying vec2 v_texCoord;    
  varying float v_Colour;    
 

 
  void main()
  {        

      vec4 u_LightPos = vec4(2.0, 5.0, -10.0, 1.0); // The position of a light in world space. should really be a uniform passed but for test, make it a fixed point in space.

     vec4 modelViewVertex = vec4(MV * a_Position);   // Transform the vertex into camera space.
     vec4 modelViewNormal = vec4(MV * vec4( a_Normal,0.0));     // Transform the normal's orientation into camera space.
       u_LightPos =   MV * u_LightPos; // put light in camera space (this could be done on the CPU but leaving it here in case you want to do other things)

    // Get a lighting direction vector from the light to the vertex.
      vec4 lightVector = normalize(u_LightPos - modelViewVertex);

    // pass the output values to the fragment
     v_Colour = max(dot(modelViewNormal, lightVector), 0.05);  // dont allow totally black ie 0.0
      v_texCoord = a_texCoord;                                        

     gl_Position = MVP * a_Position; // usual positon calc
  }

and the frag for it

Code:

    #version 100

uniform sampler2D s_texture;
varying vec2 v_texCoord;
varying float v_Colour;

void main()
{
    gl_FragColor = texture2D( s_texture, v_texCoord )*v_Colour;
    gl_FragColor.a = 1.0;
}