78 lines
2.3 KiB
GLSL
78 lines
2.3 KiB
GLSL
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// -*-C++-*-
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// Ambient term comes in gl_Color.rgb.
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#version 120
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varying vec3 vertex;
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varying vec3 relVec;
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varying vec3 normal;
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uniform float strength;
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uniform float ray_factor;
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uniform float upper_alt_factor;
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uniform float penetration_factor;
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uniform float patchiness;
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uniform float afterglow;
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uniform float arc_id;
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uniform float osg_SimulationTime;
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float Noise2D(in vec2 coord, in float wavelength);
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vec3 filter_combined (in vec3 color) ;
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void main()
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{
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float vCoord = abs(vertex.z) - 0.02 * arc_id;
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float aurora_time = 0.001 * osg_SimulationTime + arc_id;
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float noise_01 = Noise2D( vec2(vertex.x +aurora_time, vertex.y), 0.05);
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float blend_factor = smoothstep(0.935, 0.955, vCoord - 0.001 * noise_01 - 0.02 * (1.0-upper_alt_factor));
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float blend_low = smoothstep(0.915, 0.925, vCoord - 0.001 * noise_01-0.00250 * penetration_factor);
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noise_01 = smoothstep(0.0 + 0.25 * patchiness, 1.0 - 0.25 *patchiness, noise_01 - 0.5 * (1.0-strength) * patchiness);
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float noise_02 = 0.7 + 0.3 * Noise2D( vec2 (vertex.x +vertex.y, aurora_time), 0.002);
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noise_02 = mix(0.85, noise_02 , min((1.0-blend_factor) * ray_factor, 1.0));
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float smoothness = 0.01 + 0.02 * (1.0 - ray_factor);
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float noise_03 = 0.05 * (0.5 - Noise2D ( vec2 (vertex.x + vertex.y, 2.0 * aurora_time), smoothness));
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noise_03 = mix(0.0, noise_03, upper_alt_factor);
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vCoord += 0.00250 * penetration_factor;
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float vStrength = smoothstep(0.92, 0.94, vCoord) * (1.0 - smoothstep(0.94, 0.95 + 0.1 * upper_alt_factor, vCoord+noise_03));
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vec3 auroraColor1 = vec3 (0.0, 0.2, 0.1);
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vec3 auroraColor2 = vec3 (0.2, 0.0, 0.05);
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vec3 auroraColor3 = vec3 (0.8, 0.3, 0.4);
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vec3 auroraColor = mix(auroraColor1, auroraColor2, blend_factor);
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auroraColor = mix(auroraColor3, auroraColor, blend_low);
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float fade_factor = smoothstep(0.94, 0.97, vCoord - 0.001 * noise_01 - 0.02 * (1.0-upper_alt_factor));
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fade_factor = mix(1.0, fade_factor, afterglow);
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float view_angle = abs(dot(normalize(relVec), normalize(normal)));
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float angStrength = smoothstep(0.2, 0.6, view_angle);
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float auroraStrength = vStrength * angStrength * noise_01 * noise_02 * strength * fade_factor;
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vec3 finalColor = vec3 (auroraColor.x, auroraColor.y, auroraColor.z);
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finalColor.rgb = filter_combined(finalColor.rgb);
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gl_FragColor = vec4(finalColor.r, finalColor.g, finalColor.b, auroraStrength);
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}
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