Dear Group,

Can someone give me a quick overview of what effect.Alpha is supposed to do?

I have two spheres, one drawn in front of the other.  I draw the second (the one in front) with alphablending enabled in the graphicsdevice and I get a very nice blending.  Exactly what I want.  From there, I tend to experiment with various settings to understand what they do.

Effect.Alpha confuses me.  It takes a float, so I'm assuming it can be something set across a range of values, but it only seems to have two effects.  If it is zero, the alpha blended object does not appear.  Any other value, it does appear, yet the value of the setting does not seem to alter how it appears.

A second question.  Is there anything like the openGL spotlight in XNA where you can set the origin, direction, and size of the spotlight?   I see the directional lights in basiceffect, but I don't believe they will do what I want based on the settings I can uncover (i.e., something like a flashlight in a dark room).

Thanks in advance,

Byron

DrJBN:

Effect.Alpha confuses me.  It takes a float, so I'm assuming it can be something set across a range of values, but it only seems to have two effects.  If it is zero, the alpha blended object does not appear.  Any other value, it does appear, yet the value of the setting does not seem to alter how it appears.

What "any other value" did you try specifically?

The alpha property ranges from 0 to 1. It controls the opacity of the output color.

DrJBN:

A second question.  Is there anything like the openGL spotlight in XNA where you can set the origin, direction, and size of the spotlight?   I see the directional lights in basiceffect, but I don't believe they will do what I want based on the settings I can uncover (i.e., something like a flashlight in a dark room).

Thanks Shawn, I appreciate it.  I tried 0, 1, and .5, then values greater than 1.  The difference between 1 & .5 with my spheres wasn't noticable, but I can see differences between 0 and .2.

I'll delve into the Shader series shortly, and I'm sure I'll be crying for help.  

Best,

Byron