diff options
Diffstat (limited to 'doc/specs/vulkan/appendices/VK_NV_clip_space_w_scaling.txt')
| -rw-r--r-- | doc/specs/vulkan/appendices/VK_NV_clip_space_w_scaling.txt | 29 |
1 files changed, 15 insertions, 14 deletions
diff --git a/doc/specs/vulkan/appendices/VK_NV_clip_space_w_scaling.txt b/doc/specs/vulkan/appendices/VK_NV_clip_space_w_scaling.txt index 642b759..416d240 100644 --- a/doc/specs/vulkan/appendices/VK_NV_clip_space_w_scaling.txt +++ b/doc/specs/vulkan/appendices/VK_NV_clip_space_w_scaling.txt @@ -18,27 +18,28 @@ to the final post-processed image. This extension provides a mechanism to render VR scenes at a non-uniform resolution, in particular a resolution that falls linearly from the center towards the edges. -This is achieved by scaling the "w" coordinate of the vertices in the clip -space before perspective divide. -The clip space "w" coordinate of the vertices can: be offset as of a -function of "x" and "y" coordinates as follows: +This is achieved by scaling the [eq]#w# coordinate of the vertices in the +clip space before perspective divide. +The clip space [eq]#w# coordinate of the vertices can: be offset as of a +function of [eq]#x# and [eq]#y# coordinates as follows: - w' = w + Ax + By +[eq]#w' = w + Ax + By# In the intended use case for viewport position scaling, an application should use a set of 4 viewports, one for each of the 4 quadrants of a Cartesian coordinate system. Each viewport is set to the dimension of the image, but is scissored to the quadrant it represents. -The application should specify A and B coefficients of the w-scaling -equation above, that have the same value, but different signs, for each of -the viewports. -The signs of A and B should match the signs of X and Y for the quadrant that -they represent such that the value of "w'" will always be greater than or -equal to the original "w" value for the entire image. -Since the offset to "w", (Ax + By), is always positive and increases with -the absolute values of "x" and "y", the effective resolution will fall off -linearly from the center of the image to its edges. +The application should specify [eq]#A# and [eq]#B# coefficients of the +[eq]#w#-scaling equation above, that have the same value, but different +signs, for each of the viewports. +The signs of [eq]#A# and [eq]#B# should match the signs of [eq]#x# and +[eq]#y# for the quadrant that they represent such that the value of [eq]#w'# +will always be greater than or equal to the original [eq]#w# value for the +entire image. +Since the offset to [eq]#w#, ([eq]#Ax + By#), is always positive, and +increases with the absolute values of [eq]#x# and [eq]#y#, the effective +resolution will fall off linearly from the center of the image to its edges. === New Object Types |