Projection Matrices in OpenGL

Thank you to the following Patreon supporters:
- Dominic Pace
- Kevin Gregory Agwaze
- Sébastien Bervoets
- Tobias Humig
- Peter Siegmund
- Kerem Demirer

Gear I use:
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[cykablyat]

A few years late but for anyone still watching this, javidx9 has an amazing series where he tackles the graphics pipeline in depth through the use of a console and the power of the CPU.It provides a far more intuitive view over what is actually going on under the hood.

[ryanmeyers]

The minute I changed my projection matrix to no longer be centered at 0 my triangles were getting drawn in totally bizarre ways... took me half an hour to remember that matrix multiplication order matters and I was multiplying backwards in my vertex shader!

[jrpk]

The conversion of orthographic projection matrix values from relative to pixel really help explained this concept for me. The quick math demonstration at the end was perfect. Wish I could like the video twice.

[rajasbondale]

I like how he is also explaining how things far away look smaller. I mean he's just not excluding anyone with different skill levels.
Love you

[nikoszervo]

Well before these series it was extremely difficult to learn graphics API'S from the Internet. For some reason there are no good tutorials out there about that stuff even that programming is actually one of the easiest topics to learn through the internet. Very good job! Keep going! (We also can't wait for the Game Engine

[finnbuhse]

Just so everyone knows, he didn't mention that matrix multiplication is NOT commutative, and has to be matrix * vec4

[BlackJar]

Implementing your own projection matrix is very useful; it makes it easy to get the inverse. Getting the inverse very handy for shooting a ray though an arbitrary point on the screen (e.g., to find what's under a mouse pointer).

[skrolikowski]

More theory please. You can find thousands of videos already of people just coding without explanation.

[Micha-mjvg]

If your vertex positions got messed up but everything seems to be alright, it could be bacause of your shader program.
instead of
gl_Position = position * u_MVP;
write
gl_Position = u_MVP * position ;
as the matrix multiplication is NOT communicative ( mat_1 * mat_2 != mat_2 * mat_1 )

[nerijusvilcinskas]

This is exactly what I needed in order to understand how to convert SDL2 renderer stuff to OpenGL in my game, thank you so much! Projection Matrices FTW

[nox]

Another GREAT Technical Video Cherno! Much appreciated. More theory with practical application is the BEST teaching style. Theory BEFORE application is necessary for real understand, memory recall, and better applications development.

[vertigo]

I know some people below dont like the mostly talking and few coding, but I find that style to be the best. It was how my programming teachers in college taught. Basically in the 1 hour 15 minutes of course time it would be on just one topic. 45 minutes of the class to talk about logic and syntax.. do's and don'ts. History of the topic, current status, why its good, etc.. then we would have 30 minutes on the computers to play with the code.

You know what you're doing. You know the code and theory.. so you know how complex it is.. If you feel you should do it this way to make sure everyone gets it then thats probably the best way. After all you know more about this stuff then we do.

[BichoPragmatico]

you also have to use orthographic projection when implementing shadow mapping from a sun-like light source (outdoor scene), As "sun rays are parallel "

[dmasterify]

Love the theory Mr. Cherno. You ave done a great explanation of OpenGL.

Like I didn't know that GLU was the one that loaded all those function pointers. I was always confused as to how I could just call these OpenGL functions without loading them from the DLL first. Note GLU has extra functions such as GluPerspective(...).


I learnt what the hell are shaders in modern graphics libraries. I learnt about vertex shaders and fragment shaders.

I learnt that by using gl buffers you could store memory directly into the GPU. And shaders allow you to write callback functions that run on the GPU.

[violenceisfun]

6:25 reminds me of that episode of Father Ted where he's trying to explain the difference between a small sheep and a far away sheep

[timothyvandyke]

I'm very thankful for all this explanation of how things work. I finally have a grasp of what's happening when I type code!

[AxElKo]

I've been looking for this, good video. Thank you

[not_halls]

the emotionally motivating music at the start damn

[vrysk]

Would like to see an application of the concepts you've gone over, maybe in rendering a basic first person scene, but it's certainly useful to get the theory in a well-packed video too! Maybe another series?

[jairoacosta]

damn man, you saved me from pulling my hair out (edit: once again). thanks.