CMP dest, src0, src1, src2
Choose src1 if src0 >= 0. Otherwise, choose src2. The comparison is done per channel.
dest = ((src0 >= 0) ? 1.0 : 0.0) * (src1 - src2) + src2
LRP dest, src0, src1, src2
Interpolates linearly between the second and third source registers by a proportion specified in the first source register.
dest = src0 * src1 + (1-src0) * src2
// which is the same as
dest = src2 + src0 * (src1 - src2)
The above explain is different from ARB fragment, is equal to
ADD result src0, -src2
MAD result, result, src1, src2
dest = (src0 - src2) * src1 + src2 // proportion specified in src1.xyzw 后缀与默认后缀
r0.zw = tex2D(_MainTex, i.tex0);tex2D的返回内容为float4, 把它内容传递给 r0.zw 时，默认下会取 .xy 也即：r0.zw = tex2D(_MainTex, i.tex0).xy;
若该指令是从一条汇编指令直译过来，其正确写法为：r0.zw = tex2D(_MainTex, i.tex0).zw;r0.z = max(r0, r1.w);
max()函数中的 r0 默认后缀为 .x，上面等价于r0.z = max(r0.x, r1.w);
实际上该式子应该为:r0.z = max(r0.z, r1.w);- 结论：根据目标寄存器所采用的
xyzw分量的数目，会自动选择源寄存器中对应的分量组合：.x .xy .xyz .xyzw
若要有意选择 .y .z .w .yz .zw 等分量，则需要明确填写
Unity 查看Shader生成的代码
