44cabc2eec
* fix the 'slanting shadow > 75 meters' problem * lay down the shadow flat on the ground wlbragg: * add fading effect based o altitude
161 lines
7.1 KiB
GLSL
161 lines
7.1 KiB
GLSL
// -*-C++-*-
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#version 120
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uniform float hazeLayerAltitude;
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uniform float terminator;
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uniform float terrain_alt;
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uniform float overcast;
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uniform float ground_scattering;
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uniform float eye_alt;
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uniform float moonlight;
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uniform float alt_agl;
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uniform float pitch;
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uniform float roll;
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uniform float gear_clearance;
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const float EarthRadius = 5800000.0;
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const float terminator_width = 200000.0;
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void rotationMatrixPR(in float sinRx, in float cosRx, in float sinRy, in float cosRy, out mat4 rotmat)
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{
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rotmat = mat4( cosRy , sinRx * sinRy , cosRx * sinRy, 0.0,
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0.0 , cosRx , -sinRx , 0.0,
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-sinRy, sinRx * cosRy, cosRx * cosRy , 0.0,
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0.0 , 0.0 , 0.0 , 1.0 );
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}
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/*
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//Experimental - not used for now. Seems to work functionally the same as rotationMatrixPR
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void rotationMatrixRP(in float sinRx, in float cosRx, in float sinRy, in float cosRy, out mat4 rotmat)
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{
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rotmat = mat4( cosRy , sinRx * sinRy , -cosRx * sinRy, 0.0,
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0.0 , cosRx , sinRx , 0.0,
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sinRy, -sinRx * cosRy, cosRx * cosRy , 0.0,
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0.0 , 0.0 , 0.0 , 1.0 );
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}
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*/
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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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if (x < -15.0) {return 0.0;}
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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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varying float alpha_correction;
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void main()
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{
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float start_fade = 0;
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float end_fade = 100;
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float diff = end_fade - start_fade;
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alpha_correction = 1.0 - smoothstep(start_fade, end_fade, alt_agl);
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gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
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vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
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vec3 relPos = gl_Vertex.xyz - ep.xyz;
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// compute the strength of light
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float vertex_alt = max(gl_Vertex.z,100.0);
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float scattering = ground_scattering + (1.0 - ground_scattering) * smoothstep(hazeLayerAltitude -100.0, hazeLayerAltitude + 100.0, vertex_alt);
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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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float yprime = -dot(relPos, lightHorizon);
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float yprime_alt = yprime - sqrt(2.0 * EarthRadius * vertex_alt);
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float earthShade = 0.6 * (1.0 - smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt)) + 0.4;
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float lightArg = (terminator-yprime_alt)/100000.0;
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vec4 light_diffuse;
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light_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 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 = 1.0;
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light_diffuse = light_diffuse * scattering;
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float shade_depth = 1.0 * smoothstep (0.6,0.95,ground_scattering) * (1.0-smoothstep(0.1,0.5,overcast)) * smoothstep(0.4,1.5,earthShade);
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light_diffuse.rgb = light_diffuse.rgb * (1.0 + 1.2 * shade_depth);
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//experiment
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light_diffuse.b = 1.0;
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light_diffuse.g = 1.0;
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light_diffuse.r = 1.0;
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light_diffuse.a = 1.0;
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//prepare rotation matrix
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mat4 RotMatPR;
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mat4 RotMatPR_tr;
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float _roll = roll;
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//if (_roll>90.0 || _roll < -90.0) //making roll=-roll when >90 is no longer necessary thanks to fix with transpose of rotation matrix.
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//{_roll = -_roll;}
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float cosRx = cos(radians(-_roll));
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float sinRx = sin(radians(-_roll));
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float cosRy = cos(radians(pitch));
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float sinRy = sin(radians(pitch));
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rotationMatrixPR(sinRx, cosRx, sinRy, cosRy, RotMatPR);
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//rotationMatrixRP(sinRx, cosRx, sinRy, cosRy, RotMatPR);
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RotMatPR_tr=transpose(RotMatPR); //RotMatPR works fine if pitch =0 or roll=0 but if say pitch=35 and roll=60 the rotation is all wrong. transpose(RotMatPR) however works perfectly.
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// project the shadow onto the ground
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//vec4 vertex = RotMatPR * gl_Vertex;
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vec4 vertex = RotMatPR_tr * gl_Vertex;
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vec4 pos = vertex;
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vec2 deltaxy = lightFull.xy * 0.95* (alt_agl + vertex.z + gear_clearance)/lightFull.z; //This is the 'actual' location, taking into a account the full 3-D structure of the aircraft
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vec2 deltazeroxy = lightFull.xy * 0.95* (alt_agl + gear_clearance)/lightFull.z; //Instead of using the exact z value of this particularly point to determine the distance of the shadow & reposition & shrink it appropriately, we'll just use the origin (0,0,0) of the model instead. This avoids a problem below, where varying vertex.z in deltaxy and then using deltaxy to calculate dist caused the shadow to sort of slant upwards, thanks to the varying z values used
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float dist = sqrt(deltazeroxy.x * deltazeroxy.x + deltazeroxy.y * deltazeroxy.y + alt_agl * alt_agl); //could use function 'distance' instead, might be better?
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if (dist < 75)
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{
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pos.z = -0.9 * alt_agl + 0.05 * vertex.z;
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//pos.z = 0.05 * (vertex.z + gear_clearance);
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pos.xy -= deltaxy;
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}
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else
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{
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//The code below to shrink the shadow while keeping it 75 m. away has some issues that need to be fixed. Making the shadow shrink at x^2 rate partly to cover up this problem until it can be solved . . .
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//The problem is that the aircraft isn't flat/parallel to the ground any more, but it appears to be at an angle to the ground.
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//The various shrinkages perhaps mess with the angles somehow, meaning that when the animations apply the roll & pitch corrections they just don't quite work as they should
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pos.z = (-0.9*75)*alt_agl/dist + 0.05 * vertex.z ; //if the shadow is more than about 75 meters from the aircraft it disappears so we are going to just keep it right at 75 m. & make it smaller to simulate greater distance.
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//(-0.9*75) is the same factor for altitude we were using above when dist=75. *alt_agl/dist keeps it at the right height proportionally to simulate the location at a further distance, while actually just keeping it at 75 m. distance.
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//pos.z = 0.05 * vertex.z ; //if the shadow is more than about 75 meters from the aircraft it disappears so we are going to just keep it right at 75 m. & make it smaller to simulate greater distance.
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//shrink the size FIRST, THEN move where it needs to be. If you shrink later you're also shrinking the deltaxy distance moved, which doesn't work well
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pos.xy = 75 / dist * pos.xy; //shrinking the size of the shadow to simulate further distance. Should be linear shrinkage but doing it ^2 for now to help ucover up the issues in code above.
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pos.xy -= 75 * deltaxy/dist; // Similarly to above, * deltaxy/dist; keeps it at the right XY position proportionally to simulate the location at a further distance, while actually just keeping it at 75 m. distance.
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}
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// pos.z = pos.z - offset;
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//if (dist>=75) pos = pos * 30/dist; //not sure why this doesn't work/ perhaps an overflow of some kind?
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gl_Position = gl_ModelViewProjectionMatrix * pos;
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gl_FrontColor = light_diffuse;
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//light_diffuse.a=0;
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gl_BackColor = gl_FrontColor;
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//gl_BackColor = light_diffuse;
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}
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