RFR: 8234920: Add SpotLight to the selection of 3D light types [v27]

[Kevin Rushforth]

On Tue, 22 Jun 2021 10:28:16 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

>> Nir Lisker has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Updated float constant registers
>
> modules/javafx.graphics/src/main/resources/com/sun/prism/es2/glsl/main.vert line 50:
> 
>> 48: 
>> 49: varying vec4 lightTangentSpacePositions[3];
>> 50: varying vec4 lightTangentSpaceDirections[3];
> 
> `lightTangentSpacePositions` is pre existing variable. I think the name `lightTangentSpacePositions` is misguiding here. We use this variable to hold a point to light vector in tangent space. I think the name should have been something like, `tangentSpacePointToLightVec` or `pointToLightVecInTangentSpace`. Again this is not mandatory for this PR, But it did confuse me a bit while reading.
> 
> The other variable name `lightTangentSpaceDirections` sounds correct, as it holds the lights direction in tangent space, but if we change the existing variable then similarly this variable name should be also be changed.

Since this is preexisting, I probably wouldn't change it as part of this PR, but instead it could be done as part of the future work to support more than 3 lights.

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PR: https://git.openjdk.java.net/jfx/pull/334