#version 150

in vec4 vertex;
in vec4 normal;
in vec4 uv0;
in vec4 uv1; // pose1pos
in vec4 uv2; // pose1norm
in vec4 uv3; // pose2pos
in vec4 uv4; // pose2norm

// out vec2 oUv;
out vec4 colour;

uniform mat4 worldViewProj;
uniform vec4 anim_t;
uniform vec4 objSpaceLightPos;
uniform vec4 ambient;

// hardware pose animation (with normals)
void main()
{
    // interpolate position
    vec4 posinterp = vec4(vertex.xyz + anim_t.x * uv1.xyz + anim_t.y * uv3.xyz, 1.0);

    // nlerp normal
    // First apply the pose normals (these are actual normals, not offsets)
    vec3 ninterp = anim_t.x * uv2.xyz + anim_t.y * uv4.xyz;

    // Now add back any influence of the original normal
    // This depends on what the cumulative weighting left the normal at, if it's lacking or cancelled out
    //float remainder = 1.0 - min(anim_t.x + anim_t.y, 1.0);
    float remainder = 1.0 - min(length(ninterp), 1.0);
    ninterp = ninterp + (remainder * normal.xyz);
    ninterp = normalize(ninterp);

    gl_Position = worldViewProj * posinterp;
    // oUv = uv0.xy;

    vec3 lightDir = normalize(
        objSpaceLightPos.xyz - (posinterp.xyz * objSpaceLightPos.w));

    // Colour it red to make it easy to identify
    float lit = clamp(dot(lightDir, ninterp), 0.0, 1.0);
    colour = vec4((ambient.rgb + vec3(lit, lit, lit)) * vec3(1.0, 0.0, 0.0), 1.0);
}