54 lines
1.9 KiB
GLSL
54 lines
1.9 KiB
GLSL
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// -*- mode: C; -*-
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// Licence: GPL v2
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// Authors: Original code by Thorsten Jordan, Luis Barrancos and others (dangerdeep.sf.net)
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// Modified by Emilian Huminiuc (emilianh@gmail.com) (i4dnf on the flightgear forums).
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/* input:
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gl_Vertex
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gl_Normal (tangentz)
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gl_MultiTexCoord0 (texcoord)
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tangentx_righthanded (tangentx,righthanded-factor)
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*/
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/* can we give names to default attributes? or do we need to use named attributes for that?
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how to give named attributes with vertex buffer objects?
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we could assign them to a variable, but would that be efficient? an unnecessary copy.
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but the shader compiler should be able to optimize that...
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the way should be to use vertex attributes (together with vertex arrays or VBOs),
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that have a name and use that name here.
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until then, access sources directly or via a special variable.
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*/
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varying vec4 ecPosition;
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varying vec3 lightdir, halfangle;
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attribute vec4 tangent, binormal;
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void main()
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{
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ecPosition = gl_ModelViewMatrix * gl_Vertex;
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// compute direction to light in object space (L)
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vec3 lightpos_obj = vec3(gl_ModelViewMatrixInverse * gl_LightSource[0].position);
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vec3 lightdir_obj = normalize(lightpos_obj);
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// direction to viewer (E)
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// compute direction to viewer (E) in object space (mvinv*(0,0,0,1) - inputpos)
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vec3 viewerdir_obj = normalize(vec3(gl_ModelViewMatrixInverse[3]) - vec3(gl_Vertex));
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// compute halfangle vector (H = ||L+E||)
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vec3 halfangle_obj = normalize(viewerdir_obj + lightdir_obj);
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// transform light direction to tangent space
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lightdir.x = dot(tangent, lightdir_obj);
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lightdir.y = dot(binormal, lightdir_obj);
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lightdir.z = dot(gl_Normal, lightdir_obj);
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halfangle.x = dot(tangent, halfangle_obj);
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halfangle.y = dot(binormal, halfangle_obj);
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halfangle.z = dot(gl_Normal, halfangle_obj);
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// finally compute position
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gl_Position = ftransform();
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gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
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}
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