User Zack Brown | chat.stackexchange.com

CaptainRedmuff

Dec 17, 2020 17:08

Ahh, reeto. Cheers.

CaptainRedmuff

Dec 17, 2020 16:46

I need a drink :D

CaptainRedmuff

Dec 17, 2020 16:45

and the camera origin is just 0,0,0.

CaptainRedmuff

Dec 17, 2020 16:45

float4 origin = scn_frame.viewTransform * float4(0.0, 0.0, 0.0, 1.0);
float4 normal = scn_frame.viewTransform * float4(0.0, 1.0, 0.0, 0.0);
float4 direction = normalize(scn_frame.viewTransform * f.frag);

CaptainRedmuff

Dec 17, 2020 16:45

Then I swadge everything over to view space:

CaptainRedmuff

Dec 17, 2020 16:42

.frag = scn_frame.inverseViewProjectionTransform * position

CaptainRedmuff

Dec 17, 2020 16:42

Fragment position is in world space:

CaptainRedmuff

Dec 17, 2020 16:42

The gridlines are still below the floor plane, or that's how it seems when you rotate the view.

CaptainRedmuff

Dec 17, 2020 16:41

CaptainRedmuff

Dec 17, 2020 16:25

Damnit.

CaptainRedmuff

Dec 17, 2020 16:25

And now I am back where I started :D

CaptainRedmuff

Dec 17, 2020 16:21

Handy ^

CaptainRedmuff

Dec 17, 2020 16:10

So if I use inverseViewTransform for the plane the entire thing flips upside down.

CaptainRedmuff

Dec 17, 2020 16:08

Apologies. Switching coordinate spaces is baking my noodle.

CaptainRedmuff

Dec 17, 2020 16:07

Eeep.

CaptainRedmuff

Dec 17, 2020 16:03

gist.github.com/CaptainRedmuff/b52497e7f6234a03b2de01aca835a2ab

CaptainRedmuff

Dec 17, 2020 16:03

I believe that is what I am doing :|

CaptainRedmuff

Dec 17, 2020 15:58

Ahh, ok. So the inverse view projection is in camera space.

CaptainRedmuff

Dec 17, 2020 15:53

CaptainRedmuff

Dec 17, 2020 15:51

I have an object at the origin and the plane appears to be drawn a few units under it.

CaptainRedmuff

Dec 17, 2020 15:51

Using scn_frame.inverseViewProjectionTransform * position makes the grid less erratic and it looks like it aligns to the floor plane but it is still in the wrong place.

CaptainRedmuff

Dec 17, 2020 15:39

I used the modelViewProjectionTransform to move into camera space so I can do the ray casting.

CaptainRedmuff

Dec 17, 2020 15:34

I am using SceneKit and the matrices are all passed in from metal so they are correct.

CaptainRedmuff

Dec 17, 2020 14:57

The grid appears to be drawn with the right scale and proportions to the camera zoom. Changing the rotation makes the entire thing spin around wildly.

CaptainRedmuff

Dec 17, 2020 14:53

Yes, I have also multiplied the plane normal with the viewMatrix to move it into camera space.

CaptainRedmuff

Dec 17, 2020 14:50

I am certain that the ray casting and intersections are correct but it still is not right.

CaptainRedmuff

Dec 17, 2020 14:49

Thank you for the clarification.

CaptainRedmuff

Dec 17, 2020 14:13

I try to calculate the origin by multiplying it with the viewTransform.

CaptainRedmuff

Dec 17, 2020 14:12

I believe that is what I have already tried.

CaptainRedmuff

Dec 17, 2020 14:08

If I do not know the position of the camera in the shader, how do I determine where the floor is in camera space?

CaptainRedmuff

Dec 17, 2020 14:08

In world space the "floor" is also at 0, 0, 0.

CaptainRedmuff

Dec 17, 2020 14:07

It is my understanding that in camera space, the camera is at 0, 0, 0.

CaptainRedmuff

Dec 17, 2020 13:53

When I rotate the camera, the grid rotates in the opposite direction and does not appear to be aligned with the "floor" plane at all.

CaptainRedmuff

Dec 17, 2020 13:52

I can not for the life of me wrap my head around converting the appropriate parts to/from world/camera space for casting the ray.

CaptainRedmuff

Dec 17, 2020 13:50

Here is a snippet of the main parts ^

CaptainRedmuff

Dec 17, 2020 13:50

gist.github.com/CaptainRedmuff/b52497e7f6234a03b2de01aca835a2ab

CaptainRedmuff

Dec 17, 2020 13:49

Then in the fragment shader I am attempting to cast a ray from the camera onto a floor plane using the vertex position in camera space.

CaptainRedmuff

Dec 17, 2020 13:47

The vertex shader creates a stub with a the position in clip space and also in camera space.

CaptainRedmuff

Dec 17, 2020 13:46

I have made a few changes that are not in that question yet.

CaptainRedmuff

Dec 17, 2020 13:41

I am trying to figure out how to convert the world origin for the floor plane into camera space (as I think that is what I need to do).

CaptainRedmuff

Dec 17, 2020 13:41

Debugging shaders is incredibly difficult :D

CaptainRedmuff

Dec 17, 2020 13:40

It is? Ahh. I will update the question.

CaptainRedmuff

Dec 17, 2020 13:39

I am fairly confident that my ray intersection method is correct.

CaptainRedmuff

Dec 17, 2020 13:38

I am revisiting this question as I felt like I was on the right track but never really got any traction.

CaptainRedmuff

Dec 17, 2020 13:38

3

Q: Infinite world floor grid shader

I am trying to render an infinite world floor grid, similar to this question. My project is using SceneKit with Metal Shading Language but the concepts are no doubt similar between GLSL/HLSL. Here is an example project where I attempt to render a plane as a full screen quad with the grid lines...

CaptainRedmuff

Dec 17, 2020 13:38

Afternoon - anyone free to shoot the breeze about some shaders and ray casting shenanigans?

CaptainRedmuff

Apr 14, 2015 19:18

Sorry for not making myself clearer.

CaptainRedmuff

Apr 14, 2015 19:18

Thank you to everyone for the help.

CaptainRedmuff

Apr 14, 2015 19:18

@OMGtechy Yes.

CaptainRedmuff

Apr 14, 2015 19:17

@OMGtechy No. But it's a push in the right direction which was all I really wanted.

Zack Brown

Game Development