Port model shader changes for height-based emissive strength (#517)

3d-style/shaders/model.fragment.glsl

@@ -31,6 +31,7 @@ varying float v_depth_shadows;
 
 #ifdef HAS_ATTRIBUTE_a_pbr
 varying lowp vec4 v_roughness_metallic_emissive_alpha;
+varying mediump vec4 v_height_based_emission_params;
 #endif
 
 #ifdef HAS_TEXTURE_u_baseColorTexture
@@ -342,7 +343,7 @@ vec3 computeLightContribution(Material mat, vec3 lightPosition, vec3 lightColor)
     float NdotV = clamp(abs(dot(n, v)), 0.001, 1.0);
     // Just to make happy generate-metal-shaders 
     float NdotL = 0.0;
-#ifdef LIGHTING_3D_MODE
+#ifdef LIGHTING_3D_MODE 
     // For landmarks use the extended NdotL range to mimic
     // fill extrusion lighting
     NdotL = calculate_NdotL(n, l);
@@ -458,12 +459,16 @@ vec4 finalColor;
     // Apply transparency
     float opacity = mat.baseColor.w * u_opacity;
 #ifdef HAS_ATTRIBUTE_a_pbr
-    color = mix(color, v_color_mix.rgb, min(1.0, v_roughness_metallic_emissive_alpha.z));
+    float resEmission = v_roughness_metallic_emissive_alpha.z;
+
+    resEmission *= v_height_based_emission_params.z + v_height_based_emission_params.w * pow(clamp(v_height_based_emission_params.x, 0.0, 1.0), v_height_based_emission_params.y);
+
+    color = mix(color, v_color_mix.rgb, min(1.0, resEmission));
 #ifdef HAS_ATTRIBUTE_a_color_4f
     // pbr includes color. If pbr is used, color_4f is used to pass information about light geometry.
     // calculate distance to line segment, multiplier 1.3 additionally deattenuates towards extruded corners.
     float distance = length(vec2(1.3 * max(0.0, abs(color_4f.x) - color_4f.z), color_4f.y));
-    distance +=  mix(0.5, 0.0, clamp(v_roughness_metallic_emissive_alpha.z - 1.0, 0.0, 1.0));
+    distance +=  mix(0.5, 0.0, clamp(resEmission - 1.0, 0.0, 1.0));
     opacity *= v_roughness_metallic_emissive_alpha.w * saturate(1.0 - distance * distance);
 #endif
 #endif

3d-style/shaders/model.vertex.glsl

@@ -5,6 +5,18 @@ attribute vec3 a_pos_3f;
 #pragma mapbox: define-attribute highp vec3 color_3f
 #pragma mapbox: define-attribute highp vec4 color_4f
 #pragma mapbox: define-attribute-vertex-shader-only highp vec4 pbr
+#pragma mapbox: define-attribute-vertex-shader-only highp vec3 heightBasedEmissiveStrength
+
+// pbr
+// .xy - color.rgba (4 bytes)
+// .z - emissive strength (1 byte) | roughness (4 bits) | metallic (4 bits)
+// .w - heightBasedEmissionMultiplier value at interpolation Begin and Finish points (2 bytes)
+
+// heightBasedEmissiveStrength
+// .xy - interpolation parameters
+// .z - interpolation curve power
+// i.e.
+// interpolatedHeight = pow(pos_z * .x + .y, .z)
 
 uniform mat4 u_matrix;
 uniform mat4 u_lighting_matrix;
@@ -37,6 +49,11 @@ varying highp float v_depth;
 
 #ifdef HAS_ATTRIBUTE_a_pbr
 varying lowp vec4 v_roughness_metallic_emissive_alpha;
+varying mediump vec4 v_height_based_emission_params;
+// .x - height-based interpolation factor
+// .y - interpolation power
+// .z - min value
+// .w - max - min
 #endif
 
 void main() {
@@ -45,6 +62,7 @@ void main() {
     #pragma mapbox: initialize-attribute highp vec3 color_3f
     #pragma mapbox: initialize-attribute highp vec4 color_4f
     #pragma mapbox: initialize-attribute-custom highp vec4 pbr
+    #pragma mapbox: initialize-attribute-custom highp vec3 heightBasedEmissiveStrength
 
     highp mat4 normal_matrix;
 #ifdef INSTANCED_ARRAYS
@@ -99,6 +117,16 @@ void main() {
     v_color_mix = vec4(albedo_c.rgb, 1.0); // vertex color is computed on CPU
     v_roughness_metallic_emissive_alpha = vec4(vec3(r_m, e_r_m.x) / 255.0, albedo_c.a);
     v_roughness_metallic_emissive_alpha.z *= 2.0; // range [0..2] was shrank to fit [0..1]
+
+    float heightBasedRelativeIntepolation = a_pos_3f.z * heightBasedEmissiveStrength.x + heightBasedEmissiveStrength.y;
+
+    v_height_based_emission_params.x = heightBasedRelativeIntepolation;
+    v_height_based_emission_params.y = heightBasedEmissiveStrength.z;
+
+    vec2 emissionMultiplierValues = unpack_float(pbr.w) / 256.0;
+
+    v_height_based_emission_params.z = emissionMultiplierValues.x;
+    v_height_based_emission_params.w = emissionMultiplierValues.y - emissionMultiplierValues.x;
 #endif
 #ifdef FOG
     v_fog_pos = fog_position(local_pos);
@@ -124,7 +152,7 @@ void main() {
 #ifdef HAS_ATTRIBUTE_a_pbr
 #ifdef HAS_ATTRIBUTE_a_color_4f
     v_roughness_metallic_emissive_alpha.w = clamp(color_4f.a * v_roughness_metallic_emissive_alpha.w * (v_roughness_metallic_emissive_alpha.z - 1.0), 0.0, 1.0);
-#endif    
+#endif
 #endif
 
 #ifdef RENDER_SHADOWS