This, here, is some cheap, horrible bloom as a full-screen shader. And by "cheap," I mean, "you get what you pay for." Which isn't very much, these days.

The top image is a scene without the bloom. The middle image is a scene with the bloom described below. The bottom image is with the ds division removed.

Code:

---

// Bloom test:
material mat_bloom_2 {
	effect = "
		sampler2D g_samSrcColor;
		float ds;
		float4 Color;

		float4 MyShader( float2 Tex : TEXCOORD0 ) : COLOR0 {
			Color = tex2D( g_samSrcColor, Tex.xy);

			// Go four pixels out and blend them to this one:
			for(ds=1; ds<4; ds++) {
				Color += pow( tex2D( g_samSrcColor, float2(Tex.x-ds*0.002, Tex.y)), 3.0f)/ds;
				Color += pow( tex2D( g_samSrcColor, float2(Tex.x+ds*0.002, Tex.y)), 3.0f)/ds;
				Color += pow( tex2D( g_samSrcColor, float2(Tex.x, Tex.y-ds*0.002)), 3.0f)/ds;
				Color += pow( tex2D( g_samSrcColor, float2(Tex.x, Tex.y+ds*0.002)), 3.0f)/ds;
			}

			return Color;
		}

		// Just one pass:
		technique PostProcess {
			pass p1 {
				VertexShader = null;
				PixelShader = compile ps_2_0 MyShader();
			}
		}
	";
}

---

I apply this to a screen-aligned quad (requires Pro for render-to-texture). As you might be able to tell, I'm just goofing around. I don't actually know anytihng about shaders.

Yet! ;)