99 lines
3.5 KiB
GLSL
99 lines
3.5 KiB
GLSL
// -*-C++-*-
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#version 120
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varying float fogFactor;
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varying float distanceFactor;
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uniform sampler3D Noise;
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uniform float scale_x;
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uniform float scale_y;
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uniform float scale_z;
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uniform float offset_x;
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uniform float offset_y;
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uniform float offset_z;
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uniform float fade_max;
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uniform float fade_min;
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void main(void)
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{
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vec4 rawpos = gl_Vertex;
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float shade = 0.9;
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float cloud_height = 30000.0;
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// map noise vectors
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vec4 noisevec = texture3D(Noise, rawpos.xyz);
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float noise0 = (noisevec.r * 2) - 1;
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float noise1 =(noisevec.g * 2) - 1;
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vec2 noise2 = noisevec.xy;
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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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// Find a rotation matrix that rotates 1,0,0 into u. u, r and w are
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// the columns of that matrix.
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vec3 absu = abs(u);
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vec3 r = normalize(vec3(-u.y, u.x, 0));
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vec3 w = cross(u, r);
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// Do the matrix multiplication by [ u r w pos]. Scale
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// the x component first
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gl_Position = vec4(gl_Vertex.x * scale_x, 0.0, 0.0, 1.0);
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gl_Position.xyz += gl_Vertex.x * u;
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gl_Position.xyz += gl_Vertex.y * r * scale_y;
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gl_Position.xyz += gl_Vertex.z * w * scale_z;
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// Adjust the position post-rotation and scaling
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gl_Position.yz -= 3/2;
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// Offset in y and z directions using a random noise factor
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float offset_Y = (noise0 * offset_y) + offset_y/2;
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float offset_Z = (noise0 * offset_z) + offset_z/2;
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distanceFactor = 1.0 - clamp(abs(noise0), fade_min, fade_max);
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// distanceFactor = 0.5;
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gl_Position.y += offset_Y;
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gl_Position.z += offset_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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// Final position of the sprite
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gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
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// Calculate the total offset distance in the yx plane, normalised
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/*float distance = normalize(sqrt(pow(gl_Position.y, 2) + pow(gl_Position.z, 2)));
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distanceFactor = 1.0 - clamp(distance, 0.5, 1.0);*/
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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(10.0, 100.0, fogCoord), 1 - smoothstep(30000.0, 40000.0, fogCoord));
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gl_BackColor = gl_FrontColor;
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// Fog doesn't affect clouds as much as other objects.
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fogFactor = exp( -gl_Fog.density * fogCoord);
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fogFactor = clamp(fogFactor, 0.0, 1.0);
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}
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