cScale.fx

/*
    Simple texture coordinate scaling shader using vertex shaders

    BSD 3-Clause License

    Copyright (c) 2022, Paul Dang <brimson.net@gmail.com>
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are met:

    1. Redistributions of source code must retain the above copyright notice, this
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    2. Redistributions in binary form must reproduce the above copyright notice,
    this list of conditions and the following disclaimer in the documentation
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    3. Neither the name of the copyright holder nor the names of its
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    this software without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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    OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

uniform float2 _Scale <
    ui_label = "Scale";
    ui_type = "drag";
    ui_step = 0.001;
> = 1.0;

uniform float2 _Offset <
    ui_label = "Center";
    ui_type = "drag";
    ui_step = 0.001;
> = float2(0.0, 0.0);

#ifndef ENABLE_POINT_SAMPLING
    #define ENABLE_POINT_SAMPLING 0
#endif

texture2D Render_Color : COLOR;

sampler2D Sample_Color
{
    Texture = Render_Color;
    AddressU = MIRROR;
    AddressV = MIRROR;
    #if ENABLE_POINT_SAMPLING
        MagFilter = POINT;
        MinFilter = POINT;
        MipFilter = POINT;
    #else
        MagFilter = LINEAR;
        MinFilter = LINEAR;
        MipFilter = LINEAR;
    #endif
    #if BUFFER_COLOR_BIT_DEPTH == 8
        SRGBTexture = TRUE;
    #endif
};

void Scale_VS(in uint ID : SV_VERTEXID, out float4 Position : SV_POSITION, out float2 TexCoord : TEXCOORD0)
{
    TexCoord.x = (ID == 2) ? 2.0 : 0.0;
    TexCoord.y = (ID == 1) ? 2.0 : 0.0;
    Position = float4(TexCoord * float2(2.0, -2.0) + float2(-1.0, 1.0), 0.0, 1.0);

    // Scale texture coordinates from [0, 1] to [-1, 1] range
    TexCoord = TexCoord * 2.0 - 1.0;
    // Scale and offset in [-1, 1] range
    TexCoord = TexCoord * _Scale + _Offset;
    // Scale texture coordinates from [-1, 1] to [0, 1] range
    TexCoord = TexCoord * 0.5 + 0.5;
}

void Scale_PS(in float4 Position : SV_POSITION, in float2 TexCoord : TEXCOORD0, out float4 OutputColor0 : SV_TARGET0)
{
    OutputColor0 = tex2D(Sample_Color, TexCoord);
}

technique cScale
{
    pass
    {
        VertexShader = Scale_VS;
        PixelShader = Scale_PS;
        #if BUFFER_COLOR_BIT_DEPTH == 8
            SRGBWriteEnable = TRUE;
        #endif
    }
}