50 lines
1.1 KiB
Text
50 lines
1.1 KiB
Text
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/* Copyright (c) 2025, Sascha Willems
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*
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* SPDX-License-Identifier: MIT
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*
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*/
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#define HASHSCALE3 float3(443.897, 441.423, 437.195)
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#define STARFREQUENCY 0.01
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// Hash function by Dave Hoskins (https://www.shadertoy.com/view/4djSRW)
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float hash33(float3 p3)
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{
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p3 = frac(p3 * HASHSCALE3);
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p3 += dot(p3, p3.yxz+float3(19.19, 19.19, 19.19));
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return frac((p3.x + p3.y)*p3.z + (p3.x+p3.z)*p3.y + (p3.y+p3.z)*p3.x);
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}
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float3 starField(float3 pos)
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{
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float3 color = float3(0.0, 0.0, 0.0);
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float threshhold = (1.0 - STARFREQUENCY);
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float rnd = hash33(pos);
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if (rnd >= threshhold)
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{
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float starCol = pow((rnd - threshhold) / (1.0 - threshhold), 16.0);
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color += starCol.xxx;
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}
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return color;
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}
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struct VSOutput
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{
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float4 Pos : SV_POSITION;
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float3 UVW;
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};
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[shader("vertex")]
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VSOutput vertexMain(uint VertexIndex: SV_VertexID)
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{
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VSOutput output;
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output.UVW = float3((VertexIndex << 1) & 2, VertexIndex & 2, VertexIndex & 2);
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output.Pos = float4(output.UVW.xy * 2.0f - 1.0f, 0.0f, 1.0f);
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return output;
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}
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[shader("fragment")]
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float4 fragmentMain(VSOutput input)
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{
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return float4(starField(input.UVW), 1.0);
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}
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