Use color correction postprocess in map viewer

[kristiker]

Is your feature request related to a problem? Please describe.

Maps use a global postprocess file (vpost resource) that has a Color Lookup Table in it.

Describe the solution you'd like

Here is the pixel shader

// SPIR-V source (2980), SPVC_BACKEND_GLSL reflection with SPIRV-Cross by KhronosGroup
// Source 2 Viewer 7.0.0.0 - https://valveresourceformat.github.io

#version 460

struct globals
{
    float g_flColorCorrectionDefaultWeight;
    vec4 g_vViewFadeColor;
    float g_flFadeMode;
};

layout(set = 0, binding = 90) uniform texture2D g_tColorBuffer;
layout(set = 0, binding = 93) uniform texture3D g_tColorCorrection;

layout(location = 0) in vec2 PositionPs;
layout(location = 0) out vec4 vColor;

void main()
{
    vec4 vColorBuffer = textureLod(sampler2D(g_tColorBuffer, _5465), PositionPs, 0.0);
    vec3 vColorLinear = vColorBuffer.rgb;
    vec3 _25074 = mix(vColorLinear, mix(g_vViewFadeColor.xyz, g_vViewFadeColor.xyz * vColorLinear, vec3(g_flFadeMode)), vec3(g_vViewFadeColor.w));
    
    vec3 vColorGamma = SrgbLinearToGamma(_25074);

    vec3 vSampleCoord = (saturate(vColorGamma) * (31/32)) + vec3(1/(32*2));

    vColor.rgb = mix(texture(sampler3D(g_tColorCorrection, _3600), vSampleCoord).rgb, vColorGamma, vec3(g_flColorCorrectionDefaultWeight));

    vColor.rgb = SrgbGammaToLinear(vColor.rgb);
    vColor.a = vColorBuffer.a;
}

Color buffer is now avaliable as MainFrameBuffer.Color in the GLSceneViewer class. Replace GL.BlitFramebuffer with a postprocess shader invocation (fullscreen triangle pass).

The lut data can be retrieved from this

ValveResourceFormat/ValveResourceFormat/Resource/ResourceTypes/PostProcessing.cs

Lines 61 to 65 in e16dbe4

	public int GetColorCorrectionLUTDimension()
	=> Data.GetProperty<int>("m_nColorCorrectionVolumeDim");
	public byte[] GetColorCorrectionLUT()
	=> Data.GetProperty<byte[]>("m_colorCorrectionVolumeData");

Upload as RGBA8888 Tex3D with 32 slices.

Describe alternatives you've considered

No response