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flug:

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* fix the 'slanting shadow > 75 meters' problem
* lay down the shadow flat on the ground

wlbragg:
* add fading effect based o altitude
This commit is contained in:
Erik Hofman 2017-03-25 09:57:36 +01:00
parent b923ccbd47
commit 44cabc2eec
2 changed files with 83 additions and 21 deletions
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3
Shaders/shadow-ALS.frag
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@ -2,6 +2,7 @@
uniform sampler2D texture;
uniform float scattering;
varying float alpha_correction;
void main()
{
@ -15,5 +16,5 @@ void main()
texel.a = min(0.8, texel.a);
vec4 fragColor = texel;
gl_FragColor = fragColor;
gl_FragColor = fragColor * alpha_correction;;
}

97
Shaders/shadow-vol-ALS.vert
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@ -11,8 +11,8 @@ uniform float ground_scattering;
uniform float eye_alt;
uniform float moonlight;
uniform float alt_agl;
uniform float pitch;
uniform float roll;
uniform float pitch;
uniform float roll;
uniform float gear_clearance;
@ -22,12 +22,24 @@ const float terminator_width = 200000.0;
void rotationMatrixPR(in float sinRx, in float cosRx, in float sinRy, in float cosRy, out mat4 rotmat)
{
rotmat = mat4( cosRy , sinRx * sinRy , cosRx * sinRy, 0.0,
0.0 , cosRx , -sinRx * cosRx, 0.0,
-sinRy, sinRx * cosRy, cosRx * cosRy , 0.0,
0.0 , 0.0 , 0.0 , 1.0 );
rotmat = mat4( cosRy , sinRx * sinRy , cosRx * sinRy, 0.0,
0.0 , cosRx , -sinRx , 0.0,
-sinRy, sinRx * cosRy, cosRx * cosRy , 0.0,
0.0 , 0.0 , 0.0 , 1.0 );
}
/*
//Experimental - not used for now. Seems to work functionally the same as rotationMatrixPR
void rotationMatrixRP(in float sinRx, in float cosRx, in float sinRy, in float cosRy, out mat4 rotmat)
{
rotmat = mat4( cosRy , sinRx * sinRy , -cosRx * sinRy, 0.0,
0.0 , cosRx , sinRx , 0.0,
sinRy, -sinRx * cosRy, cosRx * cosRy , 0.0,
0.0 , 0.0 , 0.0 , 1.0 );
}
*/
float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
{
@ -36,9 +48,14 @@ if (x < -15.0) {return 0.0;}
return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
}
varying float alpha_correction;
void main()
{
float start_fade = 0;
float end_fade = 100;
float diff = end_fade - start_fade;
alpha_correction = 1.0 - smoothstep(start_fade, end_fade, alt_agl);
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
@ -65,36 +82,80 @@ void main()
light_diffuse.rgb = light_diffuse.rgb * (1.0 + 1.2 * shade_depth);
//experiment
light_diffuse.b = 1.0;
light_diffuse.g = 1.0;
light_diffuse.r = 1.0;
light_diffuse.a = 1.0;
//prepare rotation matrix
mat4 RotMatPR;
mat4 RotMatPR_tr;
float _roll = roll;
if (_roll>90.0 || _roll < -90.0)
{_roll = -_roll;}
float cosRx = cos(radians(_roll));
float sinRx = sin(radians(_roll));
float cosRy = cos(radians(-pitch));
float sinRy = sin(radians(-pitch));
//if (_roll>90.0 || _roll < -90.0) //making roll=-roll when >90 is no longer necessary thanks to fix with transpose of rotation matrix.
//{_roll = -_roll;}
float cosRx = cos(radians(-_roll));
float sinRx = sin(radians(-_roll));
float cosRy = cos(radians(pitch));
float sinRy = sin(radians(pitch));
rotationMatrixPR(sinRx, cosRx, sinRy, cosRy, RotMatPR);
//rotationMatrixRP(sinRx, cosRx, sinRy, cosRy, RotMatPR);
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.
// project the shadow onto the ground
vec4 vertex = RotMatPR * gl_Vertex;
//vec4 vertex = RotMatPR * gl_Vertex;
vec4 vertex = RotMatPR_tr * gl_Vertex;
vec4 pos = vertex;
pos.z = -0.9* alt_agl + 0.05 * vertex.z;
//pos.z = 0.05 * (vertex.z + gear_clearance);
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
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
float dist = sqrt(deltazeroxy.x * deltazeroxy.x + deltazeroxy.y * deltazeroxy.y + alt_agl * alt_agl); //could use function 'distance' instead, might be better?
if (dist < 75)
{
pos.z = -0.9 * alt_agl + 0.05 * vertex.z;
//pos.z = 0.05 * (vertex.z + gear_clearance);
pos.xy -= deltaxy;
}
else
{
//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 . . .
//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.
//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
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.
//(-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.
//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.
//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
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.
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.
}
// pos.z = pos.z - offset;
pos.xy -= lightFull.xy * 0.95* (alt_agl + vertex.z + gear_clearance)/lightFull.z;
//if (dist>=75) pos = pos * 30/dist; //not sure why this doesn't work/ perhaps an overflow of some kind?
gl_Position = gl_ModelViewProjectionMatrix * pos;
gl_FrontColor = light_diffuse;
//light_diffuse.a=0;
gl_BackColor = gl_FrontColor;
//gl_BackColor = light_diffuse;
}