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Added support for linear and pixel art scaling for palettized textures

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This commit is contained in:
Sam Lantinga
2025-10-04 14:16:02 -07:00
parent e1fde46a6a
commit 134b47730b
43 changed files with 11348 additions and 7598 deletions
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65
src/render/gpu/shaders/texture_advanced.frag.hlsl
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@@ -43,10 +43,12 @@ static const float TEXTURETYPE_RGB = 1;
static const float TEXTURETYPE_RGB_PIXELART = 2;
static const float TEXTURETYPE_RGBA = 3;
static const float TEXTURETYPE_RGBA_PIXELART = 4;
static const float TEXTURETYPE_PALETTE = 5;
static const float TEXTURETYPE_NV12 = 6;
static const float TEXTURETYPE_NV21 = 7;
static const float TEXTURETYPE_YUV = 8;
static const float TEXTURETYPE_PALETTE_NEAREST = 5;
static const float TEXTURETYPE_PALETTE_LINEAR = 6;
static const float TEXTURETYPE_PALETTE_PIXELART = 7;
static const float TEXTURETYPE_NV12 = 8;
static const float TEXTURETYPE_NV21 = 9;
static const float TEXTURETYPE_YUV = 10;
static const float INPUTTYPE_UNSPECIFIED = 0;
static const float INPUTTYPE_SRGB = 1;
@@ -122,21 +124,48 @@ float3 ApplyTonemap(float3 v)
return v;
}
float2 GetPixelArtUV(PSInput input)
float4 SamplePaletteNearest(float2 uv)
{
float index = texture0.Sample(sampler0, uv).r * 255;
return texture1.Sample(sampler1, float2((index + 0.5) / 256, 0.5));
}
// Implementation with thanks from bgolus:
// https://discussions.unity.com/t/how-to-make-data-shader-support-bilinear-trilinear/598639/8
float4 SamplePaletteLinear(float2 uv)
{
// scale & offset uvs to integer values at texel centers
float2 uv_texels = uv * texel_size.zw + 0.5;
// get uvs for the center of the 4 surrounding texels by flooring
float4 uv_min_max = float4((floor(uv_texels) - 0.5) * texel_size.xy, (floor(uv_texels) + 0.5) * texel_size.xy);
// blend factor
float2 uv_frac = frac(uv_texels);
// sample all 4 texels
float4 texelA = SamplePaletteNearest(uv_min_max.xy);
float4 texelB = SamplePaletteNearest(uv_min_max.xw);
float4 texelC = SamplePaletteNearest(uv_min_max.zy);
float4 texelD = SamplePaletteNearest(uv_min_max.zw);
// bilinear interpolation
return lerp(lerp(texelA, texelB, uv_frac.y), lerp(texelC, texelD, uv_frac.y), uv_frac.x);
}
float2 GetPixelArtUV(float2 uv)
{
// box filter size in texel units
float2 boxSize = clamp(fwidth(input.v_uv) * texel_size.zw, 1e-5, 1);
float2 boxSize = clamp(fwidth(uv) * texel_size.zw, 1e-5, 1);
// scale uv by texture size to get texel coordinate
float2 tx = input.v_uv * texel_size.zw - 0.5 * boxSize;
float2 tx = uv * texel_size.zw - 0.5 * boxSize;
// compute offset for pixel-sized box filter
float2 txOffset = smoothstep(1 - boxSize, 1, frac(tx));
// compute bilinear sample uv coordinates
float2 uv = (floor(tx) + 0.5 + txOffset) * texel_size.xy;
return uv;
return (floor(tx) + 0.5 + txOffset) * texel_size.xy;
}
float4 GetInputColor(PSInput input)
@@ -148,16 +177,20 @@ float4 GetInputColor(PSInput input)
} else if (texture_type == TEXTURETYPE_RGBA) {
rgba = texture0.Sample(sampler0, input.v_uv);
} else if (texture_type == TEXTURETYPE_RGBA_PIXELART) {
float2 uv = GetPixelArtUV(input);
float2 uv = GetPixelArtUV(input.v_uv);
rgba = texture0.SampleGrad(sampler0, uv, ddx(input.v_uv), ddy(input.v_uv));
} else if (texture_type == TEXTURETYPE_RGB) {
rgba = float4(texture0.Sample(sampler0, input.v_uv).rgb, 1.0);
} else if (texture_type == TEXTURETYPE_RGB_PIXELART) {
float2 uv = GetPixelArtUV(input);
float2 uv = GetPixelArtUV(input.v_uv);
rgba = float4(texture0.SampleGrad(sampler0, uv, ddx(input.v_uv), ddy(input.v_uv)).rgb, 1.0);
} else if (texture_type == TEXTURETYPE_PALETTE) {
float index = texture0.Sample(sampler0, input.v_uv).r * 255;
rgba = texture1.Sample(sampler1, float2((index + 0.5) / 256, 0.5));
} else if (texture_type == TEXTURETYPE_PALETTE_NEAREST) {
rgba = SamplePaletteNearest(input.v_uv);
} else if (texture_type == TEXTURETYPE_PALETTE_LINEAR) {
rgba = SamplePaletteLinear(input.v_uv);
} else if (texture_type == TEXTURETYPE_PALETTE_PIXELART) {
float2 uv = GetPixelArtUV(input.v_uv);
rgba = SamplePaletteLinear(uv);
} else if (texture_type == TEXTURETYPE_NV12) {
float3 yuv;
yuv.x = texture0.Sample(sampler0, input.v_uv).r;
@@ -193,7 +226,7 @@ float4 GetInputColor(PSInput input)
// Error!
rgba.r = 1.0;
rgba.g = 0.0;
rgba.b = 0.0;
rgba.b = 1.0;
rgba.a = 1.0;
}
return rgba;