👼Script: added reading verts and texcoords from Mesh.

Task 3/3 from RigsOfRods#3030.
This means I can start writing a script to batch together terrain objects (meshes+textures) for performance - especially for Community Map

New script API:
* objects: `MeshPtr, SubMesh, MeshManager`
* to get vert positions, use "array<vector3>@ __getVertexPositions()" on SubMesh
* ditto for vert texcoords, note the extra index param because mesh can have more than 1 texcoord layer: "array<vector2>@ __getVertexTexcoords(uint index)"

See example script "example_ogre_vertexData.as"

resources/scripts/example_ogre_vertexData.as

@@ -0,0 +1,192 @@
+// \title Experiment - a visual vertex/texcoord display tool
+// \brief Demo of `__getVertexPositions()` & `__getVertexTexcoords()` functions.
+// ===================================================
+
+#include "gridviewer_utils.as"
+
+GridViewer gTexcoordsViewer;
+GridViewer gVertsViewer;
+Ogre::MeshPtr gMesh;
+Ogre::TexturePtr gTex;
+array<vector3>@ gVertPositions = null;
+array<vector2>@ gVertTexcoords = null;
+int gVertViewAlongAxis = 2; // X=0, Y=1, Z=2
+float gBottomBarHeight = 50;
+color gColorViewerImageTint(1,1,1,1); // white
+color gVertColor(0.1f, 0.9f, 0.3f, 1);
+color gTexcoordColor(0.8,1,0,1);
+float gVertRadius = 1.8;
+float gTexcoordRadius = 1.6;
+int gVertNumSeg = 5;
+int gTexcoordNumSeg = 5;
+string gErrorStr = "";
+bool gShowRawTexcoords=false;
+
+float fmax(float a, float b) { return a>b?a:b; }
+float fmin(float a, float b) { return a<b?a:b; }
+
+
+
+void setupTool()
+{
+    gVertsViewer.childWindowID="Verts";
+    gVertsViewer.hAxis = 0; // X
+    gVertsViewer.vAxis = 1; // Y
+
+    gTexcoordsViewer.childWindowID="Texcoords";
+    gTexcoordsViewer.hAxis = 0; // X
+    gTexcoordsViewer.vAxis = 1; // Y
+
+    gMesh = Ogre::MeshManager::getSingleton().load("character.mesh", "MeshesRG");
+    if (gMesh.isNull())
+    {
+        gErrorStr = "couldn't load mesh";
+        return;
+    }
+    gTex = Ogre::TextureManager::getSingleton().load("character.dds", "TexturesRG");
+    if (gTex.isNull())
+    {
+        gErrorStr = "couldn't load tex";
+        return;
+    }
+
+    game.log("Num. submeshes: " + gMesh.getSubMeshes().length());
+    if (gMesh.getSubMeshes().length() == 0)
+    {
+        gErrorStr = "no submeshes";
+        return;
+    }
+
+    Ogre::SubMesh@ submesh = gMesh.getSubMeshes()[0];
+    if (@submesh == null)
+    {
+        gErrorStr = "submesh is null";
+        return;
+    }
+
+    @gVertPositions = submesh.__getVertexPositions();
+    if (@gVertPositions == null)
+    {
+        gErrorStr = "vert positions array is null";
+        return;
+    }
+
+    @gVertTexcoords = submesh.__getVertexTexcoords(0);
+    if (@gVertTexcoords == null)
+    {
+        gErrorStr = "vert texcoords array is null";
+        return;
+    }    
+}
+
+void drawGridViews()
+{
+    vector2 windowSize = ImGui::GetWindowContentRegionMax() - ImGui::GetWindowContentRegionMin();    
+    float spaceUnderViewer = 50;
+    vector2 panelSize = vector2(windowSize.x / 2, windowSize.y - (gBottomBarHeight));
+    vector2 viewerSize = vector2(windowSize.x / 2, windowSize.y - (gBottomBarHeight+spaceUnderViewer));
+
+    if (ImGui::BeginChild("leftPane",panelSize))
+    {    
+        gVertsViewer.begin(viewerSize);
+
+        // Draw the vert positions
+        for (uint i=0; i < gVertPositions.length(); i++)
+        {
+            vector2 screenPos = gVertsViewer.localToScreenPos(gVertPositions[i]);
+            ImGui::GetWindowDrawList().AddCircleFilled(screenPos, gVertRadius, gVertColor, gVertNumSeg);   
+        }
+
+        gVertsViewer.end();
+
+        if (@gVertPositions != null)
+        {
+            ImGui::TextColored( gVertColor, "Num verts: "+gVertPositions.length());
+        }   
+    }
+    ImGui::EndChild(); // "leftPane"
+
+    ImGui::SameLine();
+
+    if (ImGui::BeginChild("rightPane", panelSize))
+    {
+        if (gShowRawTexcoords)
+        {
+            if (ImGui::BeginChild("rawTexcoordsPane", viewerSize))
+            {
+                for (uint i=0; i < gVertTexcoords.length(); i++)
+                {
+                    ImGui::Text("["+i+"]    X(U)="+formatFloat(gVertTexcoords[i].x, "",5, 3)+"    Y(V)="+formatFloat(gVertTexcoords[i].y, "", 5, 3));
+                }
+            }
+            ImGui::EndChild();  //"rawTexcoordsPane"
+        }
+
+        else
+        {
+            gTexcoordsViewer.begin(viewerSize);
+
+            // draw the image
+            vector2 screenMin = gTexcoordsViewer.localToScreenPos(vector3(0,0,0));
+            vector2 screenMax = gTexcoordsViewer.localToScreenPos(vector3(gTex.getWidth(),gTex.getHeight(),1));
+            ImGui::GetWindowDrawList().AddImage(gTex, screenMin, screenMax, vector2(0,0), vector2(1,1), gColorViewerImageTint);  
+
+            // Draw the texcoords
+            for (uint i=0; i < gVertTexcoords.length(); i++)
+            {
+                vector2 screenPos = gTexcoordsViewer.localToScreenPos(vector3(gVertTexcoords[i].x*gTex.getWidth(), gVertTexcoords[i].y*gTex.getHeight(), 0));
+                ImGui::GetWindowDrawList().AddCircleFilled(screenPos, gTexcoordRadius, gTexcoordColor, gTexcoordNumSeg);            
+            }
+
+            gTexcoordsViewer.end();
+        }
+
+        if (@gVertTexcoords != null)
+        {
+            ImGui::TextColored(gTexcoordColor, "Num Texcoords: "+gVertTexcoords.length());
+            ImGui::Checkbox("Show raw texcoords", gShowRawTexcoords);
+        }        
+    }
+    ImGui::EndChild(); // "rightPane"
+}
+
+void drawBottomBar()
+{
+    ImGui::TextDisabled("Select viewing axis for the verts");   ImGui::SameLine();
+    ImGui::RadioButton("X", gVertViewAlongAxis, 0);             ImGui::SameLine();
+    ImGui::RadioButton("Y", gVertViewAlongAxis, 1);             ImGui::SameLine();
+    ImGui::RadioButton("Z", gVertViewAlongAxis, 2); 
+
+    switch (gVertViewAlongAxis)
+    {
+        case 0: gVertsViewer.hAxis=2; gVertsViewer.vAxis=1; break; // view along X: horizontal=Z, vertical=Y
+        case 1: gVertsViewer.hAxis=0; gVertsViewer.vAxis=1; break; // view along Y: horizontal=Z, vertical=X
+        case 2: gVertsViewer.hAxis=0; gVertsViewer.vAxis=1; break; // view along Z: horizontal=X, vertical=Y
+        default: ImGui::Text("ERROR: INVALID AXIS!!"); break;
+    }
+
+
+}
+
+// ================= entry points ===================
+
+void main()
+{
+    game.log("Experimental vertex position/texcoord display UI");
+    setupTool();
+}
+
+void frameStep(float dt)
+{
+    if (gErrorStr == "")
+    {
+        drawGridViews();
+    }
+    else
+    {
+        ImGui::TextDisabled("E R R O R !!");
+        ImGui::TextColored(color(1, 0.2, 0, 1), gErrorStr);
+    }
+    ImGui::Separator();
+    drawBottomBar();   
+}