Add ShaderLab language (#3490)

* Add ShaderLab language

* Update HLSL and ShaderLab grammars to latest version

* Add .shader extension back to GLSL language

* Add sample GLSL .shader files

Note that these are copies of existing GLSL samples, renamed to have
the .shader extension.

samples/GLSL/SyLens.shader

@@ -0,0 +1,161 @@
+#version 120
+
+/*
+  Original Lens Distortion Algorithm from SSontech (Syntheyes)
+  http://www.ssontech.com/content/lensalg.htm
+  
+  r2 is radius squared.
+  
+  r2 = image_aspect*image_aspect*u*u + v*v
+  f = 1 + r2*(k + kcube*sqrt(r2))
+  u' = f*u
+  v' = f*v
+
+*/
+
+// Controls
+uniform float kCoeff, kCube, uShift, vShift;
+uniform float chroma_red, chroma_green, chroma_blue;
+uniform bool apply_disto;
+
+// Uniform inputs
+uniform sampler2D input1;
+uniform float adsk_input1_w, adsk_input1_h, adsk_input1_aspect, adsk_input1_frameratio;
+uniform float adsk_result_w, adsk_result_h;
+
+float distortion_f(float r) {
+    float f = 1 + (r*r)*(kCoeff + kCube * r);
+    return f;
+}
+
+
+float inverse_f(float r)
+{
+    
+    // Build a lookup table on the radius, as a fixed-size table.
+    // We will use a vec3 since we will store the multipled number in the Z coordinate.
+    // So to recap: x will be the radius, y will be the f(x) distortion, and Z will be x * y;
+    vec3[48] lut;
+    
+    // Since out LUT is shader-global check if it's been computed alrite
+    // Flame has no overflow bbox so we can safely max out at the image edge, plus some cushion
+    float max_r = sqrt((adsk_input1_frameratio * adsk_input1_frameratio) + 1) + 0.1;
+    float incr = max_r / 48;
+    float lut_r = 0;
+    float f;
+    for(int i=0; i < 48; i++) {
+        f = distortion_f(lut_r);
+        lut[i] = vec3(lut_r, f, lut_r * f);
+        lut_r += incr;
+    }
+    
+    float t;
+    // Now find the nehgbouring elements
+    // only iterate to 46 since we will need
+    // 47 as i+1
+    for(int i=0; i < 47; i++) {
+        if(lut[i].z < r && lut[i+1].z > r) {
+            // BAM! our value is between these two segments
+            // get the T interpolant and mix
+            t = (r - lut[i].z) / (lut[i+1].z - lut[i]).z;
+            return mix(lut[i].y, lut[i+1].y, t );
+        }
+    }
+}
+
+float aberrate(float f, float chroma)
+{
+   return f + (f * chroma);
+}
+
+vec3 chromaticize_and_invert(float f)
+{
+   vec3 rgb_f = vec3(aberrate(f, chroma_red), aberrate(f, chroma_green), aberrate(f, chroma_blue));
+   // We need to DIVIDE by F when we redistort, and x / y == x * (1 / y)
+   if(apply_disto) {
+      rgb_f = 1 / rgb_f;
+   }
+   return rgb_f;
+}
+
+void main(void)
+{
+   vec2 px, uv;
+   float f = 1;
+   float r = 1;
+   
+   px = gl_FragCoord.xy;
+   
+   // Make sure we are still centered
+   px.x -= (adsk_result_w - adsk_input1_w) / 2;
+   px.y -= (adsk_result_h - adsk_input1_h) / 2;
+   
+   // Push the destination coordinates into the [0..1] range
+   uv.x = px.x / adsk_input1_w;
+   uv.y = px.y / adsk_input1_h;
+   
+       
+   // And to Syntheyes UV which are [1..-1] on both X and Y
+   uv.x = (uv.x *2 ) - 1;
+   uv.y = (uv.y *2 ) - 1;
+   
+   // Add UV shifts
+   uv.x += uShift;
+   uv.y += vShift;
+   
+   // Make the X value the aspect value, so that the X coordinates go to [-aspect..aspect]
+   uv.x = uv.x * adsk_input1_frameratio;
+   
+   // Compute the radius
+   r = sqrt(uv.x*uv.x + uv.y*uv.y);
+   
+   // If we are redistorting, account for the oversize plate in the input, assume that
+   // the input aspect is the same
+   if(apply_disto) {
+       r = r / (float(adsk_input1_w) / float(adsk_result_w));
+   }
+   
+   // Apply or remove disto, per channel honoring chromatic aberration
+   if(apply_disto) {
+      f = inverse_f(r);
+   } else {
+      f = distortion_f(r);
+   }
+   
+   vec2[3] rgb_uvs = vec2[](uv, uv, uv);
+   
+   // Compute distortions per component
+   vec3 rgb_f = chromaticize_and_invert(f);
+   
+   // Apply the disto coefficients, per component
+   rgb_uvs[0] = rgb_uvs[0] * rgb_f.rr;
+   rgb_uvs[1] = rgb_uvs[1] * rgb_f.gg;
+   rgb_uvs[2] = rgb_uvs[2] * rgb_f.bb;
+   
+   // Convert all the UVs back to the texture space, per color component
+   for(int i=0; i < 3; i++) {
+       uv = rgb_uvs[i];
+       
+       // Back from [-aspect..aspect] to [-1..1]
+       uv.x = uv.x / adsk_input1_frameratio;
+       
+       // Remove UV shifts
+       uv.x -= uShift;
+       uv.y -= vShift;
+       
+       // Back to OGL UV
+       uv.x = (uv.x + 1) / 2;
+       uv.y = (uv.y + 1) / 2;
+       
+       rgb_uvs[i] = uv;
+   }
+   
+   // Sample the input plate, per component
+   vec4 sampled;
+   sampled.r = texture2D(input1, rgb_uvs[0]).r;
+   sampled.g = texture2D(input1, rgb_uvs[1]).g;
+   sampled.b = texture2D(input1, rgb_uvs[2]).b;
+   
+   // and assign to the output
+   gl_FragColor.rgba = vec4(sampled.rgb, 1.0 );
+}