Hi

Is it possible to use Matcap images as textures for the viewport or for rendering? I am mostly talking about the shading method Zbrush uses which is shading objects based on spherical images.

thanks

sure, it's easier than you may think
here is matcap shader for mantra, for viewport you'll probably need GLSL shader

Hey thanks.

I have turned it into a VopSop and gets the message across in the SOP context so either way is cool. Thanks again for the idea and the implementation.

Btw is it possible to write GLSL shaders for Houdini?

Go to file–> new operator type –> shop type. Then in the network type, pick GLSL shader

grayOlorin
Go to file–> new operator type –> shop type. Then in the network type, pick GLSL shader

What daa? Wow, amazing. Thanks for the tip. That is cool indeed.

this seemed like a good way to dabble in glsl, so I took tamte's example and made it into a glsl shader. fun stuff! i didn't know you could use url's for texture paths, thats a clever trick.

enyhoo, here it is, with some help from axebeak, thanks!




// vertex shader
varying vec3 vPos, vN;

void main() {
vPos = vec3(gl_ModelViewMatrix * gl_Vertex);
vN = normalize ( gl_NormalMatrix * gl_Normal ) ;

gl_TexCoord = gl_MultiTexCoord0;
gl_Position = gl_ProjectionMatrix * vec4(vPos, 1.0);
}


and….

// fragment shader
uniform sampler2D g_smpTex;
uniform int glH_MaterialPass;
uniform float gamma;

varying vec3 vPos;
varying vec3 vN;

void HOUassignOutputs(vec3 emit, vec3 amb, vec3 diff, vec3 spec, float shiny, vec3 P, vec3 N, float alpha);

void main() {
vec3 c;
vec2 uv = normalize(vN) * 0.5 + 0.5;
vec3 n = normalize(vN);


if (glH_MaterialPass == 0 || glH_MaterialPass == 1) {
c = texture2D(g_smpTex, uv).rgb; // lookup color from normal
c = pow(c, gamma); // gamma correct


HOUassignOutputs(
/* emit */ c,
/* amb */ vec3(0.0),
/* diff */ vec3(0.0),
/* spec */ vec3(0.0),
/* shin */ 0.0,
/* P */ vPos,
/* N */ vN,
/* alpha */ 1.0
);
} else {
HOUassignOutputs(
/* emit */ vec3(0.0),
/* amb */ vec3(0.0),
/* diff */ vec3(0.0),
/* spec */ vec3(0.0),
/* shin */ 0.0,
/* P */ vPos,
/* N */ vec3(0.0),
/* alpha */ 1.0
);
}
}

Hey mestela, great work . These look good!

nice library of http accessable matcap images here (scroll down, copy the image links)

http://bensimonds.com/2010/07/30/matcap-generator/#more-627 [bensimonds.com]

and some locally installable ones here:

http://www.bzfusion.net/skymaps/Misc/zbrush-mats.rar [bzfusion.net]

hi

I just download the otl of mestela
Unfortunately it give me an error because of the “pow” function.
It seems my houdini doesn't recognize it.

here is the error message :
Fragment shader compile:
Fragment shader failed to compile with the following errors:
WARNING: 0:12: warning(#402) Implicit truncation of vector from size: 3 to size: 2
ERROR: 0:18: error(#202) No matching overloaded function found: pow
WARNING: 0:18: warning(#402) Implicit truncation of vector from size: 1 to size: 3
ERROR: error(#273) 1 compilation errors. No code generated

Once I erase the line with the “pow” function, everything works fine.

Can someone explain that to me ?
What did I forget ?

Thanks for your help.

vbk!!!
hi

I just download the otl of mestela
Unfortunately it give me an error because of the “pow” function.
It seems my houdini doesn't recognize it.

here is the error message :
Fragment shader compile:
Fragment shader failed to compile with the following errors:
WARNING: 0:12: warning(#402) Implicit truncation of vector from size: 3 to size: 2
ERROR: 0:18: error(#202) No matching overloaded function found: pow
WARNING: 0:18: warning(#402) Implicit truncation of vector from size: 1 to size: 3
ERROR: error(#273) 1 compilation errors. No code generated

Once I erase the line with the “pow” function, everything works fine.

Can someone explain that to me ?
What did I forget ?

Thanks for your help.

What version are you using? This doesn't even work for me it's just transparent. I tried to implement it again using Houdini 13 but not luck. I think that maybe the code its just compatible with the version they were using at that time.

Try changing the pow line to:
c = pow(c, vec3(gamma)); // gamma correct