Horde3D
http://horde3d.org/forums/

How to get light position in NDC and clip coordinates....
http://horde3d.org/forums/viewtopic.php?f=1&t=2295		 Page 1 of 1
Author:  Almahmudrony [ 21.12.2016, 07:34 ]
Post subject:  How to get light position in NDC and clip coordinates....
Hi

i having problem to get world space light position on clip space and Normalized Device Coordinates....
i have tried this to get clip coordinates in shader, vec3(-10,90,100) is the light position on world space....
Code:
vec4 v = projMat * viewMat *vec4(-10,90,100,1);
vec3 lpos = v.xyz/v.w;


but it's not resulting the exact projection location of light on screen :cry: ...

any advice could be highly appreciate....
Author:  Irdis [ 21.12.2016, 21:19 ]
Post subject:  Re: How to get light position in NDC and clip coordinates...
I don't know exactly how to solve your problem, but take a look how engine calculates the aabb of the screen that is influenced by light source:
https://github.com/horde3d/Horde3D/blob ... gLight.cpp - calcScreenSpaceAABB
Also, check functions in files in utilityLib folder.
For example:

Code:
vec4 calcViewPos( const vec4 pos )
{
   return viewMat * pos;
}


Maybe quad drawing shader can give you a hint:
Code:
[[VS_FSQUAD]]

uniform mat4 projMat;
attribute vec3 vertPos;
varying vec2 texCoords;
            
void main( void )
{
   texCoords = vertPos.xy;
   gl_Position = projMat * vec4( vertPos, 1 );
}

You can also check this link: https://www.khronos.org/opengl/wiki/Com ... ndow_space
Page 1 of 1 All times are UTC + 1 hour
Powered by phpBB® Forum Software © phpBB Group
https://www.phpbb.com/