at_tangent

in vec4 at_tangent;

Valid Programs: all gbuffers/shadow

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The tangent vector in model space. The xyz components store the tangent, and the w component stores the handedness of normal/tangent. The handedness should be used to invert the bitangent in cases where a texture is mirrored and the cross product of the normal and tangent vectors would produce an inverted bitangent vector. For example:

vec3 normal = normalMatrix * vaNormal;
vec3 tangent = normalMatrix * at_tangent.xyz;

vec3 bitangent = cross(tangent, normal) * at_tangent.w;

vec3 normal = gl_NormalMatrix * gl_Normal;
vec3 tangent = gl_NormalMatrix * at_tangent.xyz;

vec3 bitangent = cross(tangent, normal) * at_tangent.w;