surface_shader reading specific values causes wrong color

OnkelDagobert

Hi,
I'm having Problems writing the shader for a material.

<shader>	
	<inputs>		
	</inputs>
	<params>
		<param name="osPosition">true</param>
		<param name="wsPosition">true</param>
		<param name="wsNormal">true</param>
		<param name="vsNormal">true</param>
		<param name="twoSided">true</param>
		<param name="alphaTest">true</param>
	</params>
	<code>
	<![CDATA[				
		void MaterialShader(in Material_Input input, inout Material material)
		{				
			material.emissive   =    float3(0,0,1);
		}
	]]>		
	</code>
</shader>

this shader works fine and gives me this (the blue glass):


but if i try to read some vars it give me a total wrong result:

<shader>	
	<inputs>		
	</inputs>
	<params>
		<param name="osPosition">true</param>
		<param name="wsPosition">true</param>
		<param name="wsNormal">true</param>
		<param name="vsNormal">true</param>
		<param name="twoSided">true</param>
		<param name="alphaTest">true</param>
	</params>
	<code>
	<![CDATA[				
		void MaterialShader(in Material_Input input, inout Material material)
		{						
			float3 neverused = viewPoint.xyz ;			
			material.emissive   =    float3(0,0,1);
		}
	]]>		
	</code>
</shader>

the material color ALLWAYS becomes purple, no matter what i write into material.emissive

this happens if i try to read following vars:
- viewPoint
- worldToScreenMatrix
- worldToCameraMatrix
and maybe some more

even though it makes the Color purple it reads the right values from this varibales

does anyone know what to do?

or is there a way get the distance from the cam to the displaying object without using viewPoint?

Ineluki80

I'm fairly new to shaders and all (only wrote a pixel shader so far), so I wonder: where do you take viewPoint from ?
I can not see where this variable is defined nor is it an intrinsic HLSL function.
So maybe you are accessing an undefinded variable, causing a shader compile error and as a result get some default or uninitialized material instead ?
Have you had a look at the debug output messages withing the console ?

OnkelDagobert

it is defined in core\renderer\Deferred.shader_template

and as i said the value in viewPoint is correct. I tested it by adding a glow to the material depending on the viewPoint

OnkelDagobert

ok got it..
it seems that the purple color is the right behavior.
the shader used the default values specified in Deferred.shader_template:

// Setup default values so that the shader can only set the values it wants to.
material.albedo   			= float3(1, 0, 1);
material.tsNormal 			= float3(0, 0, 1);
material.opacity  			= 1;
material.specular 			= float3(0, 0, 0);
material.gloss    			= 0;
material.emissive 			= float3(0, 0, 0);
material.wsOffset 			= float3(0, 0, 0);
material.infestationShell 	= 0;	// Hack to make the infestation shell pass run
material.scale 				= 1;
material.ssDistortion 		= float2(0, 0);
material.transmissionColor 	= float3(1, 1, 1);

so a

material.albedo  = float3(0, 0,0);

fixed it

but why does the shader sometimes use these default values and sometimes not?