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/*
Copyright (c) 2008 Seneca College
Licenced under the MIT License (http://www.c3dl.org/index.php/mit-license/)
*/
// We need to create our own light structure since we can't access
// the light() function in the 2.0 context.
struct Light
{
vec4 ambient;
vec4 diffuse;
vec4 specular;
vec4 position;
vec3 halfVector;
};
struct Material
{
vec4 emission;
vec4 ambient;
vec4 diffuse;
vec4 specular;
float shininess;
};
//
// vertex attributes
//
attribute vec4 a_vertex;
attribute vec3 a_normal;
attribute vec4 a_texCoord;
// for every model we multiply the projection, view and model matrices
// once to prevent having to do it for every vertex, however we still need
// the view matrix to calculate lighting.
uniform mat4 u_modelViewMatrix;
// we can calculate this once per model to speed up processing done on the js side.
uniform mat4 u_modelViewProjMatrix;
// matrix to transform the vertex normals
uniform mat4 u_normalMatrix;
// custom light structures need to be used since we don't have access to
// light states.
uniform Light u_light;
// material
uniform vec4 u_globalAmbientColor;
uniform Material u_frontMaterial;
uniform Material u_backMaterial;
// passed to fragment shader
varying vec4 v_diffuse, v_ambient;
varying vec3 v_normal, v_lightDir;
varying vec2 v_texCoord;
/*
Given a reference to the ambient and diffuse lighting variables,
this function will calculate how much each component contributes to the scene.
Light light - the light in view space
vec3 normal -
vec4 ambient -
vec4 diffuse -
*/
vec3 directionalLight(inout vec4 ambient, inout vec4 diffuse)
{
ambient += u_light.ambient;
diffuse += u_light.diffuse;
return normalize(vec3(u_light.position));
}
void main()
{
v_normal = normalize(u_normalMatrix * vec4(a_normal, 1)).xyz;
vec4 ambient = vec4(0.0, 0.0, 0.0, 1.0);
vec4 diffuse = vec4(0.0, 0.0, 0.0, 1.0);
vec4 specular = vec4(0.0, 0.0, 0.0, 1.0);
// place the current vertex into view space
// ecPos = eye coordinate position.
vec4 ecPos4 = u_modelViewMatrix * a_vertex;
// the current vertex in eye coordinate space
vec3 ecPos = ecPos4.xyz/ecPos4.w;
v_lightDir = directionalLight(ambient, diffuse);
v_ambient = u_frontMaterial.ambient * ambient;
v_ambient += u_globalAmbientColor * u_frontMaterial.ambient;
v_diffuse = u_frontMaterial.diffuse * diffuse;
gl_Position = u_modelViewProjMatrix * a_vertex;
v_texCoord = a_texCoord.st;
}
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