A new shader to make beautifull lightbeams

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@13073 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/shaders/lightbeam.frag

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+// Jean-manuel clemencon supertuxkart
+// Creates a cone lightbeam effect by smoothing edges
+// Original idea: http://udn.epicgames.com/Three/VolumetricLightbeamTutorial.html
+// TODO: Soft edges when it intesects geometry
+//       Some artefacts are still visible
+ 
+
+uniform sampler2D main_texture;
+uniform float transparency;
+varying vec2 uv;
+varying vec3 eyeVec;
+varying vec3 normal;
+
+void main()
+{
+
+    
+    float inter = dot(normal, eyeVec);
+    float m = texture2D(main_texture, vec2(0.5, uv.y)).r;
+
+    
+    gl_FragColor = vec4(1.0,1.0,0.8, 1.0);
+
+
+    gl_FragColor.a = inter * inter * inter * inter * m;
+}

data/shaders/lightbeam.vert

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+// Jean-manuel clemencon supertuxkart
+// Creates a cone lightbeam effect by smoothing edges
+ 
+
+uniform float time;
+varying vec2 uv;
+varying vec3 eyeVec;
+varying vec3 normal;
+
+void main()
+{
+	gl_TexCoord[0] = gl_MultiTexCoord0;
+	gl_Position = gl_ModelViewMatrix * gl_Vertex;
+
+
+    eyeVec = normalize(-gl_Position).xyz; 
+    normal = gl_NormalMatrix * gl_Normal;
+
+    gl_Position = ftransform();
+
+    uv = gl_TexCoord[0].st;
+}