Add Color Parameter Type float4 to .hlsl and User Input

[EricBanker12]

Expected behavior 预期的功能

Expected Behavior:

• .hlsl effects can have //!PARAMETER for color with type float4
• Users can pick color from a ColorPicker to set parameter value.

//!PARAMETER
//!LABEL Color 0
//!RED 1.0
//!GREEN 1.0
//!BLUE 1.0
//!ALPHA 1.0
float4 Color_0;

Currently, shaders with color input must split color into many float parameters. Additionally, users must configure color using multiple sliders with no color preview.

For example, in my Shaders-for-Magpie repository, Nostolgia.hlsl, which emulates 8-bit color, requires 48 float sliders with no color preview to set up a custom 8-bit color palette.

I tried to add this functionality myself, but I got stuck. I could not understand how values are passed to shader to create float4.

Alternative behavior (optional) 近似的功能（可选）

Alternative Behavior:

• .hlsl effects can have //!PARAMETER for color with 4 consecutive type float.
• Users can pick color from a ColorPicker to set parameter values.

//!PARAMETER
//!LABEL Color 0
//!RED 1.0
//!GREEN 1.0
//!BLUE 1.0
//!ALPHA 1.0
float Color_0_Red, Color_0_Green, Color_0_Blue, Color_0_Alpha;

Alternative:

//!PARAMETER
//!LABEL Color 0
//!DEFAULT 1.0
//!COLOR 0
float Color_0_Red;

//!PARAMETER
//!LABEL Color 0
//!DEFAULT 1.0
//!COLOR 1
float Color_0_GREEN;

//!PARAMETER
//!LABEL Color 0
//!DEFAULT 1.0
//!COLOR 2
float Color_0_Blue;

//!PARAMETER
//!LABEL Color 0
//!DEFAULT 1.0
//!COLOR 3
float Color_0_Alpha;

[Blinue]

This feature is fantastic and will also benefit existing effects like ImageAdjustment. I'm currently working on MagpieFX Version 4, where this functionality will be included.

The syntax for Magpie's effects is still unstable at the moment. Until the first official release (which won't be too far off), I won't be able to maintain compatibility with older versions. Please take note of this.