added some ambient lighting + fixed shading

src/shaders/grassFragment.glsl

@@ -16,5 +16,8 @@ void main() {
     float ndl2 = max(dot(-normalW, lightDirection), 0.0);
     float ndl = ndl1 + ndl2;
 
+    // ambient lighting
+    ndl = clamp(ndl + 0.1, 0.0, 1.0);
+
     gl_FragColor = vec4(finalColor * ndl, 1.0);// apply color and lighting
 } 

src/shaders/grassVertex.glsl

@@ -22,10 +22,11 @@ void main() {
     float leanAmount = 0.3;
     float curveAmount = leanAmount * position.y;
     vec3 rotatedPosition = rotateAround(position, vec3(1.0, 0.0, 0.0), curveAmount);
+    vec3 rotatedNormal = rotateAround(normal, vec3(1.0, 0.0, 0.0), curveAmount);
 
     vec4 outPosition = viewProjection * finalWorld * vec4(rotatedPosition, 1.0);
     gl_Position = outPosition;
 
     normalMatrix = transpose(inverse(finalWorld));
-    vNormal = normal;
+    vNormal = rotatedNormal;
 }

src/ts/index.ts

@@ -46,7 +46,7 @@ grassBlade.material = material;
 
 const grassBlades = [];
 const patchSize = 10;
-const patchResolution = 20;
+const patchResolution = 50;
 const cellSize = patchSize / patchResolution;
 const patchPosition = new Vector3(0, 0, 0);