我仍在从事一个图像处理项目，该项目利用 HLSL 着色器添加 Photoshop 式过滤器，如投影、斜角等。现在我正在寻找一种在 HLSL 中实现外发光效果的方法。
我目前正在尝试以下想法：
1）缩放当前纹理以创建发光（参数：glowSize，设置轮廓的大小）
2) 水平模糊
3）模糊垂直，将模糊颜色更改为发光颜色并在顶部添加原始纹理
我正在使用以下多通道 HLSL 着色器来渲染发光：
float4 PS_Scale(VS_OUTPUT IN) : COLOR0
{
float2 tex = IN.texture0;
float2 scaleCenter = float2(0.5f, 0.5f);
float2 scaleTex = (tex - scaleCenter) * glowSize + scaleCenter;
return tex2D(foreground, scaleTex);
}
float4 PS_GlowH(VS_OUTPUT IN) : COLOR0
{
float2 Tex = IN.texture0;
float4 sum = float4(0.0, 0.0, 0.0, 0.0);
sum += tex2D(secondForeground, float2(Tex.x - 4.0*blur, Tex.y))*0.05;
sum += tex2D(secondForeground, float2(Tex.x - 3.0*blur, Tex.y))*0.09;
sum += tex2D(secondForeground, float2(Tex.x - 2.0*blur, Tex.y))*0.12;
sum += tex2D(secondForeground, float2(Tex.x - blur, Tex.y))*0.15;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y))*0.16;
sum += tex2D(secondForeground, float2(Tex.x + blur, Tex.y))*0.15;
sum += tex2D(secondForeground, float2(Tex.x + 2.0*blur, Tex.y))*0.12;
sum += tex2D(secondForeground, float2(Tex.x + 3.0*blur, Tex.y))*0.09;
sum += tex2D(secondForeground, float2(Tex.x + 4.0*blur, Tex.y))*0.05;
return sum;
}
float4 PS_GlowV(VS_OUTPUT IN) : COLOR0
{
float2 Tex = IN.texture0;
float4 sum = float4(0.0, 0.0, 0.0, 0.0);
sum += tex2D(secondForeground, float2(Tex.x, Tex.y - 4.0*blur))*0.05;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y - 3.0*blur))*0.09;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y - 2.0*blur))*0.12;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y - blur))*0.15;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y))*0.16;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y + blur))*0.15;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y + 2.0*blur))*0.12;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y + 3.0*blur))*0.09;
sum += tex2D(secondForeground, float2(Tex.x, Tex.y + 4.0*blur))*0.05;
float4 result = sum * opacity;
result.rgb = float3(glowColor.r, glowColor.g, glowColor.b) / 255.0f;
float4 src = tex2D(foreground, IN.texture0.xy);
return result * (1-src.a) + src;
}
使用椭圆等简单形状时，此代码的结果看起来不错，但在文本上应用着色器时不起作用：
很明显，缩放存在问题。我不知道如何缩放原始纹理以将其用作轮廓。这甚至可能吗？任何其他想法如何在 HLSL 中实现外部发光或轮廓过滤器？
先感谢您。
