Blinn Phong Shading: Theory and Implementation [Shaders Monthly #4] 

Many times before I got stuck with radiance and BRDF math, but this video finally allowed me to understand it. This is the best video on lighting computations on RU-vid. Big thank you!

Hi professor! Thank you so much for making this very high quality resources publicly available. I'm studying PBR rendering at the moment and found your videos through a RU-vid search. Yours is the best resource I was able to find that involves both math/theory and code/implementation. ^_^ I got confused by the meaning of theta, and definitions of and relations between irradiance and radiance. AFAIU, on slide 14 when you explain irradiance, around t=18:55, theta is the angle between the incoming light direction and the surface normal. Again in slide 14, when you explain radiance, around t=20:30, theta is the angle between the outgoing/reflected light direction (view direction) and the surface normal. you say that's why we multiple dA with cos(theta), to get the projected area. Again in slide 14, when you explain the relationship from incoming radiance to irradiance, around t=22:18, theta again becomes the angle of incidence. oh! I think I got it now! In the third case we are talking about the incoming radiance, but in the second case we were talking about outgoing radiance. We always use theta, but meaning of theta changes depending on whether the radiance we are interested in is incoming or outgoing wrt surface. Lol, it took me a few days to finally grasp this and that happened while I was writing this question. :-) I'm glad I posed the question. Still gonna leave my comment here in case anyone else got confused about the same concepts. One tiny bit confusing aspect that was left in my mind is that, the outgoing radiance, the essential quantity that we are calculating in our shaders, by definition has a cos(theta_prime) in it. (called it prime to distinguish it from angle of incidence). However, AFAIU, by definition, BRDF handles the "projected area" for that case... I mean, the integral to calculate L_o(v) is kind of a transformation of irradiance from l-space to v-space via the BRDF kernel, and by definition, the direction v is into our eye/camera. so, theta_prime is always 90. At least, this is how I'm going to sooth my mind. :-)

Wonderful video, I found it very insightful and I enjoy you sharing knowledge like this. I'm 13 years old and for the longest time have been studying computer graphics beyond the artistic 3D interfaces. Learning the different types of shading: Blinn, Phong, Blinn-Phong, PhongE, and Anisotropic has been so mind opening. The things someone sees in blender and Octane, and then the deep history behind it allows you to fully appreciate the time and effort the goes into making that concept and proofing it. That's why I love your channel ;), you're too underrated and more people need to look into stuff like this.

Thanks!! I am trying to make all lession you do here in Touchdesigner!! Your composer is the best web madness i ever saw. Thanks for what you share. You made me a better artist . ❤

You deserve more views and likes friend! Awesome content!!! Thank you very much!

While I don't write code for shaders, I do spend quite a bit of time rendering. It really puts into perspective what high end 3d packages do behind the scenes. Thank you!

Wonderfull videos, thank you

Thank you, wonderful video.

Thank you

This is an awesome video series thank you so much at 7:05 you said that use of three primary colors has something to do with the fact that we have 3 cones where can we get more info on this topic? i though that we use RGB model mostly for technical reasons (im guessing its easier/better to produce red green and blue diode screens than lets say cymk) is there really a link of some kind between how our cones work and how rgb models are defined?

Hi, very nice video! I just have a simple question, the output value of the fragment shader is RGB color or linear radiance？Because I saw that the `outColor` ball light was called `rgb2lin`, but when coloring the object, `lin2rgb` was also called, so I was confused？

Such a great video! Anyway, could you provide the literature references (i.e. book or journal article) that explain the Phong model equation in this video? Because I saw in several paper the equation slightly different. Thank you!

I've a second question, thanks for calculating these radiation quantities for point light! Are you going to do the same for directional lights, later in the course? Because I'm having difficulty in wrapping my head around visualizing radiant intensity of a directional light (i.e. a light model that does not have position, and it's direction is constant through space, a good approximation of sunlight on earth's surface) because I can't surround its source via spherical shell.