153 lines
4.2 KiB
GLSL
153 lines
4.2 KiB
GLSL
// Implementation based on:
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// "The Best Darn Grid Shader (Yet)", Medium, Oct 2023
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// Ben Golus
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// https://bgolus.medium.com/the-best-darn-grid-shader-yet-727f9278b9d8#3e73
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#define USE_FORWARD true;
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#include "./Flax/Common.hlsl"
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META_CB_BEGIN(0, Data)
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float4x4 ViewProjectionMatrix;
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float4 GridColor;
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float3 ViewPos;
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float Far;
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float3 ViewOrigin;
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float GridSize;
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META_CB_END
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// Geometry data passed to the vertex shader
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struct ModelInput
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{
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float3 Position : POSITION;
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};
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// Interpolants passed from the vertex shader
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struct VertexOutput
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{
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float4 Position : SV_Position;
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float2 TexCoord : TEXCOORD0;
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float3 WorldPosition : TEXCOORD1;
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};
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// Interpolants passed to the pixel shader
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struct PixelInput
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{
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float4 Position : SV_Position;
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noperspective float2 TexCoord : TEXCOORD0;
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float3 WorldPosition : TEXCOORD1;
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};
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// Vertex shader function for grid rendering
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META_VS(true, FEATURE_LEVEL_ES2)
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META_VS_IN_ELEMENT(POSITION, 0, R32G32B32_FLOAT, 0, ALIGN, PER_VERTEX, 0, true)
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META_VS_IN_ELEMENT(TEXCOORD, 0, R16G16_FLOAT, 1, ALIGN, PER_VERTEX, 0, true)
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VertexOutput VS_Grid(ModelInput input)
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{
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VertexOutput output;
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output.WorldPosition = input.Position.xyz + ViewOrigin;
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float3 geoPosition = input.Position.xyz - float3(0, ViewOrigin.y, 0);
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output.Position = mul(float4(geoPosition, 1), ViewProjectionMatrix);
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return output;
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}
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float invLerp(float from, float to, float value)
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{
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return (value - from) / (to - from);
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}
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float remap(float origFrom, float origTo, float targetFrom, float targetTo, float value)
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{
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float rel = invLerp(origFrom, origTo, value);
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return lerp(targetFrom, targetTo, rel);
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}
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float ddLength(float a)
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{
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return length(float2(ddx(a), ddy(a)));
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}
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float GetLine(float pos, float scale, float thickness)
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{
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float lineWidth = thickness;
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float coord = (pos * 0.01) * scale;
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float2 uvDDXY = float2(ddx(coord), ddy(coord));
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float deriv = float(length(uvDDXY.xy));
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float drawWidth = clamp(lineWidth, deriv, 0.5);
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float lineAA = deriv * 1.5;
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float gridUV = abs(coord);
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float grid2 = smoothstep(drawWidth + lineAA, drawWidth - lineAA, gridUV);
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grid2 *= saturate(lineWidth / drawWidth);
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grid2 = lerp(grid2, lineWidth, saturate(deriv * 2.0 - 1.0));
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float grid = lerp(grid2, 1.0, grid2);
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return grid;
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}
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float GetGrid(float3 pos, float scale, float thickness)
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{
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float lineWidth = thickness;
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float2 coord = (pos.xz * 0.01) * scale;
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float4 uvDDXY = float4(ddx(coord), ddy(coord));
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float2 deriv = float2(length(uvDDXY.xz), length(uvDDXY.yw));
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float2 drawWidth = clamp(lineWidth, deriv, 0.5);
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float2 lineAA = deriv * 1.5;
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float2 gridUV = 1.0 - abs(frac(coord) * 2.0 - 1.0);
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float2 grid2 = smoothstep(drawWidth + lineAA, drawWidth - lineAA, gridUV);
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grid2 *= saturate(lineWidth / drawWidth);
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grid2 = lerp(grid2, lineWidth, saturate(deriv * 2.0 - 1.0));
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float grid = lerp(grid2.x, 1.0, grid2.y);
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return grid;
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}
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float4 GetColor(float3 pos, float scale)
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{
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float dist = 1 - saturate(distance(float3(ViewPos.x, 0, ViewPos.z), pos) / GridSize);
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// Line width
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float g1LW = 0.01;
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// Major line Z
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float l1 = GetLine(pos.x, 1, g1LW * 2);
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// Major line X
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float l2 = GetLine(pos.z, 1, g1LW);
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// Main grid
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float g1 = GetGrid(pos, 1, g1LW * 0.8);
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float g2 = GetGrid(pos, 2, g1LW * 0.4);
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float g3 = GetGrid(pos, 0.1, g1LW * 2);
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float camFadeLarge = clamp(invLerp(2500, 4000, abs(ViewPos.y)),0, g3);
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g3 *= camFadeLarge;
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float g4 = GetGrid(pos, 10, g1LW);
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float camFadeTiny = clamp(invLerp(150, 100, abs(ViewPos.y)), 0, g4);
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g4 *= camFadeTiny;
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float grid = 0;
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grid = max(l1, l2);
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grid = max(grid, g1);
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grid = max(grid, g2);
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grid = max(grid, g3);
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grid = max(grid, g4);
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float4 color = grid * GridColor;
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color = lerp(color, float4(1,0,0,1), l2);
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color = lerp(color, float4(0,0,1,1), l1);
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color *= dist;
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color *= 1 - saturate(length(pos) - 600000); // Fade out when far from origin (60km)
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return color;
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}
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// Pixel shader function for grid rendering
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META_PS(true, FEATURE_LEVEL_ES2)
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float4 PS_Grid(PixelInput input) : SV_Target
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{
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float4 color = GetColor(input.WorldPosition, 1);
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return color;
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}
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