Hi

Iâ€™m new to hlsl shaders and I recently made a pixel shader for a pixel font. I first draw the game text to a full screen rendertarget and then apply the pixel shader. It looks like this:

**before**

**after**

The shader is fairly heavy because of the multiple outlines (still a bit better than drawing the text 30+ times with drawstring to recreate the same effect) , **so Iâ€™m curious if I can optimize this shader to be faster.**

This is the shader: (**edit**)

`#if OPENGL #define SV_POSITION POSITION #define VS_SHADERMODEL vs_3_0 #define PS_SHADERMODEL ps_3_0 #else #define VS_SHADERMODEL vs_4_0_level_9_1 #define PS_SHADERMODEL ps_4_0_level_9_1 #endif`

`float2 texelSize; int shadow; Texture2D SpriteTexture;`

`sampler2D SpriteTextureSampler = sampler_state { Texture = <SpriteTexture>; };`

`struct VertexShaderOutput { float4 Color : COLOR0; float2 TextureCoordinates : TEXCOORD0; };`

`float4 MainPS(VertexShaderOutput input) : COLOR { float4 color = tex2D(SpriteTextureSampler, input.TextureCoordinates) * input.Color;`

`if (!color.a) { float2 offsetX = float2(texelSize.x, 0); float2 offsetY = float2(0, texelSize.y); float alpha = color.a;`

`alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY - offsetX).a);`

`if (alpha) { return float4(1, 1, 1, alpha); }`

`alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetX + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetY).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetY - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetY + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetX + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY + offsetX + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetY + offsetX + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY + offsetX + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY + offsetY - offsetX - offsetX).a);`

`if (alpha) { return float4(0.18f, 0.18f, 0.18f, alpha); }`

`if (shadow == 1) { alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetX - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetY).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates + offsetY - offsetX - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetX - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetY - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetY + offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetX - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetY - offsetX - offsetX).a); alpha = max(alpha, tex2D(SpriteTextureSampler, input.TextureCoordinates - offsetY - offsetY - offsetY - offsetX - offsetX - offsetX).a);`

`if (alpha) { return float4(0.09f, 0.09f, 0.09f, alpha); } }`

}

return color;

}

`technique SpriteDrawing { pass P0 { PixelShader = compile PS_SHADERMODEL MainPS(); } };`

Iâ€™m simply testing if a pixel is in a certain range of an outline and give it the corresponding color. One pixel in the shader does not correspond to one pixel in the font. Thatâ€™s why I have the for loops.

Thanks in advance.