vertex_shader
	"varying vec3 texcoord;

	void main()
	{
		gl_Position = ftransform();
		texcoord = gl_MultiTexCoord0.xyz;
	}";

fragment_shader
	"uniform sampler3D texture;
	varying vec3 texcoord;

	void main()
	{
		float heat = max((texture3D(texture, texcoord).r-0.1)*12.0, 0.0);
		gl_FragColor = vec4(1.0, heat, max(heat-1.0, 0.0), heat/4.0);
	}";