75 lines
2.5 KiB
GLSL
75 lines
2.5 KiB
GLSL
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#version 330 core
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layout(location = 0) in vec4 pos;
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layout(location = 2) in vec4 vertexColor;
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layout(location = 3) in vec4 multiTexCoord0;
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out vec2 texCoord;
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out vec4 cloudColor;
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uniform mat4 osg_ModelViewMatrix;
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uniform mat4 osg_ModelViewProjectionMatrix;
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uniform mat4 osg_ViewMatrixInverse;
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uniform vec3 fg_SunDirectionWorld;
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const float shade = 0.8;
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const float cloud_height = 1000.0;
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// aerial-perspective-include.frag
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vec3 add_aerial_perspective(vec3 color, vec2 coord, float depth);
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vec3 get_sun_radiance(vec3 p);
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void main()
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{
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texCoord = multiTexCoord0.st;
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// XXX: Should be sent as an uniform
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mat4 inverseModelViewMatrix = inverse(osg_ModelViewMatrix);
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vec4 ep = inverseModelViewMatrix * vec4(0.0, 0.0, 0.0, 1.0);
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vec4 l = inverseModelViewMatrix * vec4(0.0, 0.0, 1.0, 1.0);
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vec3 u = normalize(ep.xyz - l.xyz);
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vec4 final_pos = vec4(0.0, 0.0, 0.0, 1.0);
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final_pos.x = pos.x;
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final_pos.y = pos.y;
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final_pos.z = pos.z;
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final_pos.xyz += vertexColor.xyz;
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gl_Position = osg_ModelViewProjectionMatrix * final_pos;
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// Determine a lighting normal based on the vertex position from the
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// center of the cloud, so that sprite on the opposite side of the cloud
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// to the sun are darker.
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vec3 n = normalize(vec3(osg_ViewMatrixInverse *
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osg_ModelViewMatrix * vec4(-final_pos.xyz, 0.0)));
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float NdotL = dot(-fg_SunDirectionWorld, n);
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vec4 final_view_pos = osg_ModelViewMatrix * final_pos;
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vec4 final_world_pos = osg_ViewMatrixInverse * final_view_pos;
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float fogCoord = abs(final_view_pos.z);
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float fract = smoothstep(0.0, cloud_height, final_pos.z + cloud_height);
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vec3 sun_radiance = get_sun_radiance(final_world_pos.xyz);
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// Determine the shading of the sprite based on its vertical position and
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// position relative to the sun.
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NdotL = min(smoothstep(-0.5, 0.0, NdotL), fract);
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// Determine the shading based on a mixture from the backlight to the front
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vec3 backlight = shade * sun_radiance;
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cloudColor.rgb = mix(backlight, sun_radiance, NdotL);
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// Perspective division and scale to [0, 1] to get the screen position
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// of the vertex.
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vec2 coord = (gl_Position.xy / gl_Position.w) * 0.5 + 0.5;
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cloudColor.rgb = add_aerial_perspective(
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cloudColor.rgb, coord, length(final_view_pos));
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// As we get within 100m of the sprite, it is faded out. Equally at large
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// distances it also fades out.
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cloudColor.a = min(smoothstep(100.0, 250.0, fogCoord),
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1.0 - smoothstep(70000.0, 75000.0, fogCoord));
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}
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