A basic shader for the bubble gum shield effect

git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@13445 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/shaders/gum_shield.frag

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+// Jean-manuel clemencon (c) supertuxkart 2013
+// bubble gum shield
+// TODO: Add a nice texture and soft edges when intersect with geometry
+
+uniform sampler2D tex;
+uniform float transparency;
+
+varying vec2 uv;
+varying vec3 eyeVec;
+varying vec3 normal;
+
+void main()
+{
+	float inter = dot(normal, eyeVec);
+	float m = texture2D(tex, vec2(0.5, uv.y)).r;
+	inter = 1 - inter;
+	float alpha = inter + 1;// * m;
+
+	gl_FragColor = vec4(0.8, 0.16, 0.48, alpha);
+}

data/shaders/gum_shield.vert

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+// Jean-manuel clemencon (c) supertuxkart 2013
+// Creates a bubble gum shield effect
+// ---
+// TODO: The texture should reflect the strength of the shield, 
+// such that the user gets to know whether the shield has several 
+// "layers" or whether the shield is about to break. 
+
+varying vec2 uv;
+varying vec3 eyeVec;
+varying vec3 normal;
+
+void main()
+{
+	gl_TexCoord[0] = gl_MultiTexCoord0;
+	vec4 viewp = gl_ModelViewMatrix * gl_Vertex;
+
+	eyeVec = normalize(-viewp).xyz;
+	normal = gl_NormalMatrix * gl_Normal;
+
+	gl_Position = ftransform();
+
+	uv = gl_TexCoord[0].st;
+}