Add persistent contrail Shaders/contrail.frag Shaders/contrail.vert

Signed-off-by: Vivian Meazza <vivian.meazza@lineone.net>

Shaders/contrail.frag

@@ -0,0 +1,15 @@
+uniform sampler2D baseTexture;
+
+varying float fogFactor;
+varying float distanceFactor;
+varying vec2  texCoord;
+
+
+void main(void)
+{
+    vec4 base = texture2D( baseTexture, gl_TexCoord[0].st);
+    vec4 finalColor = base * gl_Color;
+    gl_FragColor.rgb = mix(gl_Fog.color.rgb, finalColor.rgb, fogFactor);
+    gl_FragColor.a = mix(0.0, finalColor.a, distanceFactor);
+}
+

Shaders/contrail.vert

@@ -0,0 +1,99 @@
+// -*-C++-*-
+#version 120
+
+varying float fogFactor;
+varying float distanceFactor;
+
+uniform sampler3D Noise;
+
+uniform float scale_x;
+uniform float scale_y;
+uniform float scale_z;
+
+uniform float offset_x;
+uniform float offset_y;
+uniform float offset_z;
+
+uniform float fade_max;
+uniform float fade_min;
+
+void main(void)
+{
+    vec4 rawpos     = gl_Vertex;
+
+    float shade = 0.9;
+    float cloud_height = 30000.0;
+
+    // map noise vectors
+    vec4 noisevec = texture3D(Noise, rawpos.xyz);
+    float noise0 = (noisevec.r * 2) - 1;
+    float noise1 =(noisevec.g * 2) - 1;
+    vec2 noise2 = noisevec.xy;
+
+    gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
+    //gl_TexCoord[0] = gl_MultiTexCoord0 + vec4(textureIndexX, textureIndexY, 0.0, 0.0);
+    vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
+    vec4 l  = gl_ModelViewMatrixInverse * vec4(0.0,0.0,1.0,1.0);
+    vec3 u = normalize(ep.xyz - l.xyz);
+
+    // Find a rotation matrix that rotates 1,0,0 into u. u, r and w are
+    // the columns of that matrix.
+    vec3 absu = abs(u);
+    vec3 r = normalize(vec3(-u.y, u.x, 0));
+    vec3 w = cross(u, r);
+
+    // Do the matrix multiplication by [ u r w pos]. Scale
+    // the x component first
+    gl_Position = vec4(gl_Vertex.x * scale_x, 0.0, 0.0, 1.0);
+    gl_Position.xyz += gl_Vertex.x * u;
+    gl_Position.xyz += gl_Vertex.y * r * scale_y;
+    gl_Position.xyz += gl_Vertex.z * w * scale_z;
+
+    // Adjust the position post-rotation and scaling
+    gl_Position.yz -= 3/2;
+
+    // Offset in y and z directions using a random noise factor
+    float offset_Y = (noise0 * offset_y) + offset_y/2;
+    float offset_Z = (noise0 * offset_z) + offset_z/2;
+
+    distanceFactor = 1.0 - clamp(abs(noise0), fade_min, fade_max);
+//    distanceFactor = 0.5;
+
+    gl_Position.y += offset_Y;
+    gl_Position.z += offset_Z;
+
+    gl_Position.xyz += gl_Color.xyz;
+
+    // Determine a lighting normal based on the vertex position from the
+    // center of the cloud, so that sprite on the opposite side of the cloud to the sun are darker.
+    float n = dot(normalize(-gl_LightSource[0].position.xyz),
+        normalize(mat3x3(gl_ModelViewMatrix) * (- gl_Position.xyz)));;
+
+    // Determine the position - used for fog and shading calculations
+    vec3 ecPosition = vec3(gl_ModelViewMatrix * gl_Position);
+    float fogCoord = abs(ecPosition.z);
+    float fract = smoothstep(0.0, cloud_height, gl_Position.z + cloud_height);
+
+    // Final position of the sprite
+    gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
+
+    // Calculate the total offset distance in the yx plane, normalised
+    /*float distance = normalize(sqrt(pow(gl_Position.y, 2) + pow(gl_Position.z, 2)));
+    distanceFactor = 1.0 - clamp(distance, 0.5, 1.0);*/
+    // Determine the shading of the sprite based on its vertical position and position relative to the sun.
+    n = min(smoothstep(-0.5, 0.0, n), fract);
+
+    // Determine the shading based on a mixture from the backlight to the front
+    vec4 backlight = gl_LightSource[0].diffuse * shade;
+
+    gl_FrontColor = mix(backlight, gl_LightSource[0].diffuse, n);
+    gl_FrontColor += gl_FrontLightModelProduct.sceneColor;
+
+    // As we get within 100m of the sprite, it is faded out. Equally at large distances it also fades out.
+    gl_FrontColor.a = min(smoothstep(10.0, 100.0, fogCoord), 1 - smoothstep(30000.0, 40000.0, fogCoord));
+    gl_BackColor = gl_FrontColor;
+
+    // Fog doesn't affect clouds as much as other objects.
+    fogFactor = exp( -gl_Fog.density * fogCoord);
+    fogFactor = clamp(fogFactor, 0.0, 1.0);
+}