56 lines
2 KiB
GLSL
56 lines
2 KiB
GLSL
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// -*-C++-*-
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#version 120
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varying float fogFactor;
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float shade = 0.8;
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float cloud_height = 1000.0;
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void main(void)
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{
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gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
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//gl_TexCoord[0] = gl_MultiTexCoord0 + vec4(textureIndexX, textureIndexY, 0.0, 0.0);
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vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
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vec4 l = gl_ModelViewMatrixInverse * vec4(0.0,0.0,1.0,1.0);
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vec3 u = normalize(ep.xyz - l.xyz);
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gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
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gl_Position.x = gl_Vertex.x;
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gl_Position.y += gl_Vertex.y;
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gl_Position.z += gl_Vertex.z;
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gl_Position.xyz += gl_Color.xyz;
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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 to the sun are darker.
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float n = dot(normalize(-gl_LightSource[0].position.xyz),
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normalize(mat3x3(gl_ModelViewMatrix) * (- gl_Position.xyz)));;
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// Determine the position - used for fog and shading calculations
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vec3 ecPosition = vec3(gl_ModelViewMatrix * gl_Position);
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float fogCoord = abs(ecPosition.z);
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float fract = smoothstep(0.0, cloud_height, gl_Position.z + cloud_height);
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gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
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// Determine the shading of the sprite based on its vertical position and position relative to the sun.
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n = min(smoothstep(-0.5, 0.0, n), fract);
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// Determine the shading based on a mixture from the backlight to the front
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vec4 backlight = gl_LightSource[0].diffuse * shade;
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gl_FrontColor = mix(backlight, gl_LightSource[0].diffuse, n);
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gl_FrontColor += gl_FrontLightModelProduct.sceneColor;
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// As we get within 100m of the sprite, it is faded out. Equally at large distances it also fades out.
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gl_FrontColor.a = min(smoothstep(100.0, 250.0, fogCoord), 1.0 - smoothstep(70000.0, 75000.0, fogCoord));
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gl_BackColor = gl_FrontColor;
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// Fog doesn't affect rain as much as other objects.
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fogFactor = exp( -gl_Fog.density * fogCoord * 0.4);
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fogFactor = clamp(fogFactor, 0.0, 1.0);
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}
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