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voxel-game/assets/shaders/gui_box.slang

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import "includes/math";
import "includes/structs";
struct Varyings {
float4 positionCS : SV_Position;
nointerpolation uint instance;
float2 positionSSPX;
}
struct GuiBox {
float4 backgroundColor;
float4 borderColor;
float2 positionSSPX;
float2 sizePX;
float borderWidthPX;
float borderRadiusPX;
}
[[vk::binding(0, 0)]] ConstantBuffer<GlobalUniforms> _Global;
[[vk::binding(1, 0)]] StructuredBuffer<GuiBox> _Boxes;
static const float2 VERTICES[4] = {
float2(0, 1),
float2(1, 1),
float2(0, 0),
float2(1, 0),
};
[shader("vertex")]
Varyings vertexMain(uint vertexID : SV_VulkanVertexID, uint instanceID : SV_VulkanInstanceID) {
Varyings out;
let vertex = VERTICES[vertexID];
let box = _Boxes[instanceID];
let positionSSPX = vertex * box.sizePX + box.positionSSPX;
let positionCS = float4(mul(_Global.matrixSSPXtoCS, float3(positionSSPX, 1.0)), 0.0, 1.0);
out.positionCS = positionCS;
out.instance = instanceID;
out.positionSSPX = positionSSPX;
return out;
}
[shader("fragment")]
float4 fragmentMain(Varyings frag) : SV_Target {
let box = _Boxes[frag.instance];
let halfExtentsPX = 0.5 * box.sizePX;
let centerSSPX = box.positionSSPX + halfExtentsPX;
let borderHalfWidthPX = 0.5 * box.borderWidthPX;
let interiorSDF = boxSDF(frag.positionSSPX, centerSSPX, halfExtentsPX, box.borderRadiusPX) + box.borderWidthPX;
float borderSDF = abs(interiorSDF - borderHalfWidthPX) - borderHalfWidthPX;
float interiorCoverage = saturate(-interiorSDF + 0.5) * box.backgroundColor.a;
float borderCoverage = saturate(-borderSDF + 0.5) * box.borderColor.a;
float totalCoverage = interiorCoverage + borderCoverage;
return float4(
interiorCoverage * box.backgroundColor.rgb +
borderCoverage * box.borderColor.rgb,
totalCoverage,
);
}