#32 Support for Vulkan NDC.

[Anonymous]

Originally created by: cheako

https://matthewwellings.com/blog/the-new-vulkan-coordinate-system/

define GLM_DEPTH_ZERO_TO_ONE

define GLM_FORCE_LEFT_HANDED

[Anonymous]

Originally posted by: recp

It would be great to have that feature!

Actually it is in TODOs but since I'm not working on Vulkan yet, I can't test it. Currently I'm working on a render engine (http://github.com/recp/gk) which is based on OpenGL. In the future I'll implement Vulkan API, I can't work on it until that time.

If anyone want to implement it before me, it would be appreciated. Otherwise I will postpone this until I implemented Vulkan in my render engine.

[Anonymous]

Originally posted by: cheako

From my research this should adjust OpenGL NDC to Vulkan NDC.

  mat4 oglproj;
  glm_perspective_default((float)extent.width / (float)extent.height, oglproj);
  /* This is for Vulkan, cglm is for OpenGL. */
  glm_mat4_mul((mat4){{1.0f, 0.0f, 0.0f, 0.0f},
                      {0.0f, -1.0f, 0.0f, 0.0f},
                      {0.0f, 0.0f, 0.5f, 0.5f},
                      {0.0f, 0.0f, 0.0f, 1.0f}},
               oglproj, projection);

[Anonymous]

Originally posted by: recp

Excellent! But in the future we should provide OPTION macro as your first proposal like glm e.g. GLM_DEPTH_ZERO_TO_ONE, GLM_FORCE_LEFT_HANDED

My main concern is this requires extra CPU cycles and memory :-S also makes codes more complex, I don't think someone would want to extra matrix multiplication

Actually I don't need to Vulkan to implement ZER_TO_ONE check this answer:
https://stackoverflow.com/a/21841924/2676533

Traditional OpenGL behavior is:
glClipControl (GL_LOWER_LEFT, GL_NEGATIVE_ONE_TO_ONE);

Direct3D behavior can be achieved through:
glClipControl (GL_UPPER_LEFT, GL_ZERO_TO_ONE); // Y-axis is inverted in D3D

I may try to change my render engine's NDC by glClipControl to implement Vulkan NDC later. Hope glClipControl is doing what I'm thinking.

Since there are a lot of things to do in importer, renderer and cglm... I can't give a deadline for NDC configurations :( but I'll start working on it. I created a branch called ndc, maybe we should start implement Vulkan NDC asap. I will push Vulkan NDC related stuff to this branch. If you or/and others want to help to implementation (by codes, by comments, by reviews, especially testing it...), it would boost the process.