i wrote a pixelshader which avoids the disadvantages of d3d_autotransparency.

you have to use a 32bit tga texture. all pixels with alpha values above 0.5 will be rendered completely opaque and all other pixels will be rendered completely transparent. it's possible to enable the z-buffer then, so you won't have any sorting errors!

currently it can't be used for sprites because shaders don't seem to work with them...

in my opinion it looks better than overlays looked in a5.24 because there are no jagged edges!

Code:

---

...

ZWriteEnable=true;

AlphaTestEnable=true;

...

PixelShader= 

asm

{

  ps.1.3

  def c0,1,1,1,1

  def c1,0,0,0,0

  tex t0               // sample t0

  mov r0,t0

  cnd r0.a,r0.a,c0,c1  // if(r0.a>0.5){r0.a=1;}else{r0.a=0;}

  mul r0.rgb,r0,v0     // modulate with diffuse vertex lighting

};

---

entities using this shader should have my.flare=off; and my.transparent=off; so that the engine won't unnecessarily sort them!

here is a screenshot:

i found out that exactly the same can be done without a pixelshader!

Code:

---

material mat_vegetation

{

	effect=

	"	

		texture texSkin1;

		dword mtlSkill1;

		technique vegetation

		{

			pass p0

			{

				Texture[0]=<texSkin1>;



				ZWriteEnable=true;

				AlphaTestEnable=true;

				AlphaRef=<mtlSkill1>;

				AlphaFunc=greater;

				//CullMode=none;

				

				ColorArg1[0]=Texture;

				ColorOp[0]=Modulate2x;

				ColorArg2[0]=Diffuse;

			}

		}

	";

}



starter mat_vegetation_init

{

	...

	mat_vegetation.skill1=pixel_for_vec(vector(127,0,0),0,8888);

}

---

this version even allows to adjust the threshold via the first value of the vector in the starter function!

Which version of A6 are you using to do this?

currently it does only work with the beta version. i guess the directx effects will be available in 6.2 commercial/pro!

if you use this material for plant models it could be useful to enable double sided polygons. just add this line:

CullMode=none;

What type of FPS hit is there for 30-50 of these polys using this technique, vs normal overlays?

i haven't done any serious benchmarks yet but with enabled backface culling (which is also enabled with normal overlays) i haven't observed a performance hit. if two-sided polygons get used (CullMode=none;), the fps seem to drop a little. i have a meadow with 500 grass triangles and fps dropped from ~80 to ~72!

Question for ventilator.. do you have an idea how i could add this technique to my diff+spec shader? i have tried several methods.. with no success. If do an extra pass at the bieginngin with this fixed function code the alpha mask works wbut the subsequent passes are nullified. ANyone know how this stuff works.. multi passes and alpha blending etc?

i don't have much experience with multipass rendering but you could try to add the cnd line

def c0,1,1,1,1
def c1,0,0,0,0
...
cnd r0.a,r0.a,c0,c1 // if(r0.a>0.5){r0.a=1;}else{r0.a=0;}

to both passes? (of course you have to modify it so that it uses the correct alphachannel in both passes...)

hmm.. yes i think you're on the right track.. its sort of working.. now i have to figure out how the blending should be set up