diff --git a/css-transforms-2/Overview.bs b/css-transforms-2/Overview.bs index 5cd222a8837..3b7ee4a0a52 100644 --- a/css-transforms-2/Overview.bs +++ b/css-transforms-2/Overview.bs @@ -122,7 +122,7 @@ Terminology {#terminology} ''rotateY(0)'', ''rotateZ(0)'' and ''matrix3d(1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1)''. - A special case is perspective: ''perspective(infinity)''. + A special case is perspective: ''perspective(none)''. The value of m₃₄ becomes infinitesimal small and the transform function is therefore assumed to be equal to the identity matrix. @@ -983,7 +983,7 @@ In the following 3d transform functions, a <> behaves th :: same as ''rotate3d(0, 1, 0, <angle>)''. : rotateZ() = rotateZ( [ <> | <> ] ) :: same as ''rotate3d(0, 0, 1, <angle>)'', which is a 3d transform equivalent to the 2d transform ''rotate(<angle>)''. -: perspective() = perspective( <> ) +: perspective() = perspective( <> | ''none'' ) :: specifies a perspective projection matrix. This matrix scales points in X and Y based on their Z value, scaling points with positive Z values away from the origin, and those with negative Z values towards the origin. Points on the z=0 plane are unchanged. The parameter represents the distance of the z=0 plane from the viewer. Lower values give a more flattened pyramid and therefore a more pronounced perspective effect. For example, a value of 1000px gives a moderate amount of foreshortening and a value of 200px gives an extreme amount. If the depth value is less than ''1px'', @@ -1378,9 +1378,12 @@ One translation unit on a matrix is equivalent to 1 pixel in the local coordinat

- A perspective projection matrix with the parameter d is equivalent to the matrix: + A perspective projection matrix with the parameter d is equivalent to the matrix: - $$\begin{bmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & -1/d & 1 \end{bmatrix}$$ + $$\begin{bmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & -1/d & 1 \end{bmatrix}$$ + + If the parameter d is ''none'' it is treated as infinity + (and the resulting matrix is the identity matrix).