implement grid and heightmap with lambert shading

src/app_shaders.cpp

@@ -485,7 +485,28 @@ void App::initShaders()
         "void main(){"
         "   frag = c;"
         "}";
-    
+
+    // LAMBERT
+    static const char* shader_lambert_v =
+        SHADER_VERSION
+        "uniform mat4 mvp;\n"
+        "in vec4 pos;\n"
+        "in vec3 nor;\n"
+        "out vec3 n;\n"
+        "void main(){\n"
+        "   n = nor;\n"
+        "   gl_Position = mvp * pos;\n"
+        "}";
+    static const char* shader_lambert_f =
+        SHADER_VERSION
+        "uniform mediump vec3 light_dir;\n"
+        "in mediump vec3 n;\n"
+        "out mediump vec4 frag;\n"
+        "void main(){\n"
+        "   mediump float d = max(0.0, dot(normalize(n), light_dir));\n"
+        "   frag = vec4(vec3(d), 1.0);\n"
+        "}";
+
 
     LOG("initializing shaders");
     if (!ShaderManager::create(kShader::Texture, shader_v, shader_f))
@@ -524,6 +545,8 @@ void App::initShaders()
         LOG("Failed to create shader BrushStroke");
     if (!ShaderManager::create(kShader::VertexColor, shader_vertcol_v, shader_vertcol_f))
         LOG("Failed to create shader VertexColor");
+    if (!ShaderManager::create(kShader::Lambert, shader_lambert_v, shader_lambert_f))
+        LOG("Failed to create shader Lambert");
     LOG("shaders initialized");
 }