def BlinnPhong_specular(incident_vector, view_vector, surface_norm, shininess_exponent):
""" Return the Blinn-Phong specular intensity for a given light reflection into a viewpoint on a surface with a shininess factor.
Source adapted from: http://ruh.li/GraphicsPhongBlinnPhong.html
Ref: Blinn, James F. (1977): Models of light reflection for computer synthesized pictures
"""
specularIntensity = 0.0
""" Should the view_vector be negated? I see it is in various places.
"""
#view_vector = -view_vector
if (np.dot(incident_vector, surface_norm) > 0.0):
halfwayVector = normalize(incident_vector + view_vector)
specTmp = max(np.dot(surface_norm, halfwayVector), 0.0)
specularIntensity = pow(specTmp, shininess_exponent)
return specularIntensity
def BlinnPhong_specular(incident_vector, view_vector, surface_norm, shininess_exponent, intensity=1.0):
""" Return the Blinn-Phong specular intensity for a given light reflection into a viewpoint on a surface with a shininess factor.
Source adapted from: http://ruh.li/GraphicsPhongBlinnPhong.html
Ref: Blinn, James F. (1977): Models of light reflection for computer synthesized pictures
"""
specularIntensity = 0.0
""" Should the view_vector be negated? I see it is in various places.
"""
#view_vector = -view_vector
if (np.dot(incident_vector, surface_norm) > 0.0):
halfwayVector = normalize(incident_vector + view_vector)
specTmp = max(np.dot(surface_norm, halfwayVector), 0.0)
specularIntensity = pow(specTmp, shininess_exponent)
return float(intensity * specularIntensity)
def Lambert_diffuse( incident_vector, surface_norm, intensity ):
"""
Calculate lambert's cosine law of diffuse reflectance.
Cosine and dot product will yield equivalence, under condition:
- https://en.wikipedia.org/wiki/Dot_product#Equivalence_of_the_definitions
Source adapted from: http://pyopengl.sourceforge.net/context/tutorials/shader_5.html
"With our normal and our directional light, we can apply Lambert's law to calculate the
diffuse component multiplier for any given vertex. Lambert's law looks for the cosine
of the two vectors (the Normal and the Light Location vector), which is calculated by
taking the dot product of the two (normalized) vectors."
"""
normalized_incident_vec = normalize(incident_vector)
return float(intensity * max( 0.0, np.dot(surface_norm , normalized_incident_vec) ))
def Lambert_diffuse( incident_vector, surface_norm ):
"""
Adapted from source: http://pyopengl.sourceforge.net/context/tutorials/shader_5.html
"""
normalized_incident_vec = normalize(incident_vector)
return max( 0.0, np.dot(surface_norm , normalized_incident_vec) )
