**diff options**

Diffstat (limited to 'doc/specs/vulkan/appendices')

3 files changed, 44 insertions, 42 deletions

diff --git a/doc/specs/vulkan/appendices/VK_EXT_blend_operation_advanced.txt b/doc/specs/vulkan/appendices/VK_EXT_blend_operation_advanced.txt index f6b9701..5244152 100644 --- a/doc/specs/vulkan/appendices/VK_EXT_blend_operation_advanced.txt +++ b/doc/specs/vulkan/appendices/VK_EXT_blend_operation_advanced.txt @@ -53,9 +53,9 @@ according to the pname:srcPremultiplied and pname:dstPremultiplied members of slink:VkPipelineColorBlendAdvancedStateCreateInfoEXT. If a color is considered non-premultiplied, the (R,G,B) color components are multiplied by the alpha component prior to blending. -For non-premultiplied color components in the range eq#[0,1]#, the +For non-premultiplied color components in the range [eq]#[0,1]#, the corresponding premultiplied color component would have values in the range -eq#[0 {times} A, 1 {times} A]#. +[eq]#[0 {times} A, 1 {times} A]#. Many of these advanced blending equations are formulated where the result of blending source and destination colors with partial coverage have three 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 diff --git a/doc/specs/vulkan/appendices/VK_NV_viewport_swizzle.txt b/doc/specs/vulkan/appendices/VK_NV_viewport_swizzle.txt index f299f00..e55a05d 100644 --- a/doc/specs/vulkan/appendices/VK_NV_viewport_swizzle.txt +++ b/doc/specs/vulkan/appendices/VK_NV_viewport_swizzle.txt @@ -20,10 +20,10 @@ single-pass cubemap rendering (broadcasting a primitive to multiple faces and reorienting the vertex position for each face) and voxel rasterization. The per-viewport component remapping and negation provided by the swizzle allows application code to re-orient three-dimensional geometry with a view -along any of the X, Y, or Z axes. -If a perspective projection and depth buffering is required, 1/W buffering -should be used, as described in the single-pass cubemap rendering example in the "Issues" section below. +along any of the *X*, *Y*, or *Z* axes. +If a perspective projection and depth buffering is required, [eq]#1/W# +buffering should be used, as described in the single-pass cubemap rendering example in === New Object Types @@ -74,8 +74,8 @@ rendering to a cubemap. In this example, the application would attach a cubemap texture to a layered FBO where the six cube faces are treated as layers. Vertices are sent through the vertex shader without applying a projection -matrix, where the gl_Position output is (x,y,z,1) and the center of the -cubemap is at (0,0,0). +matrix, where the code:gl_Position output is [eq]#(x,y,z,1)# and the center +of the cubemap is at [eq]#(0,0,0)#. With unextended Vulkan, one could have a conventional instanced geometry shader that looks something like the following: @@ -184,39 +184,40 @@ not need to be modified as part of this coordinate transformation. Note that while the rotate() operation in the regular geometry shader above could include an arbitrary post-rotation projection matrix, the viewport swizzle does not support arbitrary math. -To get proper projection, 1/W buffering should be used. +To get proper projection, [eq]#1/W# buffering should be used. To do this: 1. -Program the viewport swizzles to move the pre-projection W eye coordinate -(typically 1.0) into the Z coordinate of the swizzle output and the eye -coordinate component used for depth into the W coordinate. -For example, the viewport corresponding to the +Z face might use a swizzle -of (+X, -Y, +W, +Z). -The Z normalized device coordinate computed after swizzling would then be -z'/w' = 1/Z_eye. +Program the viewport swizzles to move the pre-projection [eq]#W# eye +coordinate (typically 1.0) into the [eq]#Z# coordinate of the swizzle output +and the eye coordinate component used for depth into the [eq]#W# coordinate. +For example, the viewport corresponding to the [eq]#+Z# face might use a +swizzle of [eq]#(+X, -Y, +W, +Z)#. +The [eq]#Z# normalized device coordinate computed after swizzling would then +be [eq]#z'/w' = 1/Z~eye~#. 2. On NVIDIA implementations supporting floating-point depth buffers with -values outside [0,1], prevent unwanted near plane clipping by enabling +values outside [eq]#[0,1]#, prevent unwanted near plane clipping by enabling DEPTH_CLAMP. Ensure that the depth clamp doesn't mess up depth testing by programming the -depth range to very large values, such as minDepthBounds=-z, -maxDepthBounds=+z), where z == 2^127. -It should be possible to use IEEE infinity encodings also (0xFF800000 for --INF, 0x7F800000 for +INF). +depth range to very large values, such as [eq]#pname:minDepthBounds=-z#, +[eq]#pname:maxDepthBounds=+z#, where [eq]#z = 2^127^#. +It should be possible to use IEEE infinity encodings also (`0xFF800000` for +`-INF`, `0x7F800000` for `+INF`). Even when near/far clipping is disabled, primitives extending behind the eye -will still be clipped because one or more vertices will have a negative W -coordinate and fail X/Y clipping tests. +will still be clipped because one or more vertices will have a negative +[eq]#W# coordinate and fail [eq]#X#/[eq]#Y# clipping tests. -On other implementations, scale X, Y, and Z eye coordinates so that vertices -on the near plane have a post-swizzle W coordinate of 1.0. -For example, if the near plane is at Z_eye = 1/256, scale X, Y, and Z by -256. +On other implementations, scale [eq]#X#, [eq]#Y#, and [eq]#Z# eye +coordinates so that vertices on the near plane have a post-swizzle [eq]#W# +coordinate of 1.0. +For example, if the near plane is at [eq]#Z~eye~ = 1/256#, scale [eq]#X#, +[eq]#Y#, and [eq]#Z# by 256. 3. -Adjust depth testing to reflect the fact that 1/W values are large near the -eye and small away from the eye. +Adjust depth testing to reflect the fact that [eq]#1/W# values are large +near the eye and small away from the eye. Clear the depth buffer to zero (infinitely far away) and use a depth test of GREATER instead of LESS. |