uniform sampler3D volume;
uniform float blackAlpha;

void main(void)
{
	vec4 texel = texture3D(volume, gl_TexCoord[0].xyz);

	vec3 color = vec3(1,1,1) * texel.a * 2.0;

	gl_FragData[0] = vec4(color, mix(1.0, texel.a * 2.0, blackAlpha)) * gl_Color;
}
