139 lines
5 KiB
GLSL
139 lines
5 KiB
GLSL
// -*-C++-*-
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#version 120
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varying float fogFactor;
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varying vec3 hazeColor;
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varying vec3 relVector;
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varying float flogz;
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uniform float range; // From /sim/rendering/clouds3d-vis-range
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uniform float scattering;
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uniform float terminator;
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uniform float altitude;
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uniform float flash;
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uniform float lightning_pos_x;
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uniform float lightning_pos_y;
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uniform float lightning_range;
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float shade = 0.8;
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float cloud_height = 1000.0;
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const float EarthRadius = 5800000.0;
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// light_func is a generalized logistic function fit to the light intensity as a function
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// of scaled terminator position obtained from Flightgear core
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float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
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{
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x = x-0.5;
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return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
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}
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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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relVector = gl_Position.xyz - ep.xyz;
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gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
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// logarithmic depth
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flogz = 1.0 + gl_Position.w;
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// Light at the final position
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// first obtain normal to sun position
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vec3 lightFull = (gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz;
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vec3 lightHorizon = normalize(vec3(lightFull.x,lightFull.y, 0.0));
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// yprime is the distance of the vertex into sun direction, corrected for altitude
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float vertex_alt = max(altitude * 0.30480 + relVector.z,100.0);
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float yprime = -dot(relVector, lightHorizon);
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float yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
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// compute the light at the position
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vec4 light_diffuse;
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float lightArg = (terminator-yprime_alt)/100000.0;
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light_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 2.827, 1.08e-05, 1.0);
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light_diffuse.g = light_func(lightArg, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0);
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light_diffuse.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0);
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light_diffuse.a = 0.0;
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//light_diffuse = light_diffuse * scattering;
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float intensity = length(light_diffuse);
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light_diffuse = intensity * normalize(mix(light_diffuse, 2.0*vec4 (0.55, 0.6, 0.8, 1.0), (1.0 - smoothstep(0.3,0.8, scattering))));
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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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// two times terminator width governs how quickly light fades into shadow
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float terminator_width = 200000.0;
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float earthShade = 0.9 * smoothstep(terminator_width+ terminator, -terminator_width + terminator, yprime_alt) + 0.1;
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gl_FrontColor.rgb = gl_FrontColor.rgb * earthShade;
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// lightning
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vec2 lightningRelVector = relVector.xy - vec2(lightning_pos_x, lightning_pos_y);
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float rCoord = length(lightningRelVector);
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vec3 flashColor = 2.0 * flash * vec3 (0.43, 0.57, 1.0) * (1.0 - smoothstep(lightning_range, 5.0 * lightning_range, rCoord));
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gl_FrontColor.rgb += flashColor;
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gl_FrontColor.rgb = clamp(gl_FrontColor.rgb,0.0,1.0);
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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(range*0.9, range, 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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float fadeScale = 0.05 + 0.2 * log(fogCoord/1000.0);
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if (fadeScale < 0.05) fadeScale = 0.05;
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fogFactor = exp( -gl_Fog.density * 1.0 * fogCoord * fadeScale);
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hazeColor = light_diffuse.rgb;
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hazeColor.x = hazeColor.x * 0.83;
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hazeColor.y = hazeColor.y * 0.9;
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hazeColor = hazeColor * scattering;
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// change haze color to blue hue for strong fogging
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intensity = length(hazeColor);
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hazeColor = intensity * normalize(mix(hazeColor, 2.0 * vec3 (0.55, 0.6, 0.8), (1.0-smoothstep(0.3,0.8,scattering))));
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hazeColor = clamp(hazeColor * earthShade, 0.0,1.0);
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}
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