From a111bfc17f4d6b88c12f63d1c4ee8b582e4926dc Mon Sep 17 00:00:00 2001
From: fgenesis <false.genesis@googlemail.com>
Date: Sat, 26 Aug 2023 00:14:05 +0200
Subject: [PATCH] use VBO to render tile borders

Also fix oversight in DynamicGPUBuffer::drawElements(); first wasn't used
---
 BBGE/Core.cpp         |  5 ++++-
 BBGE/Core.h           |  2 ++
 BBGE/TileRender.cpp   | 16 ++++------------
 BBGE/VertexBuffer.cpp | 12 ++++++++----
 4 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/BBGE/Core.cpp b/BBGE/Core.cpp
index 65abe60..61fc609 100644
--- a/BBGE/Core.cpp
+++ b/BBGE/Core.cpp
@@ -158,6 +158,8 @@ void Core::setup_opengl()
 	TexCoordBox	defaultTC;
 	defaultTC.setStandard();
 	defaultQuadGrid.init(2, 2, defaultTC);
+
+	defautQuadBorder.initQuadVertices(defaultTC, GPUACCESS_DEFAULT);
 }
 
 void Core::resizeWindow(int w, int h, int full, int bpp, int vsync, int display, int hz)
@@ -281,7 +283,7 @@ static bool checkWritable(const std::string& path, bool warn, bool critical)
 
 
 Core::Core(const std::string &filesystem, const std::string& extraDataDir, int numRenderLayers, const std::string &appName, int particleSize, std::string userDataSubFolder)
-: ActionMapper(), StateManager(), appName(appName)
+: ActionMapper(), StateManager(), appName(appName), defautQuadBorder(GPUBUF_STATIC | GPUBUF_VERTEXBUF)
 {
 	window = NULL;
 	sound = NULL;
@@ -1922,6 +1924,7 @@ void Core::shutdown()
 	debugLog("OK");
 
 	defaultQuadGrid.dropBuffers();
+	defautQuadBorder.dropBuffer();
 
 	debugLog("Shutdown Graphics Library...");
 		shutdownGraphicsLibrary();
diff --git a/BBGE/Core.h b/BBGE/Core.h
index 29509dd..e4ca150 100644
--- a/BBGE/Core.h
+++ b/BBGE/Core.h
@@ -413,6 +413,7 @@ public:
 	TextureMgr texmgr;
 
 	inline const RenderGrid *getDefaultQuadGrid() const { return &defaultQuadGrid; }
+	inline const DynamicGPUBuffer *getDefaultQuadBorderBuf() const { return &defautQuadBorder; }
 
 protected:
 
@@ -492,6 +493,7 @@ protected:
 	void clearActionButtons();
 
 	RenderGrid defaultQuadGrid;
+	DynamicGPUBuffer defautQuadBorder;
 
 public:
 	// inclusive!
diff --git a/BBGE/TileRender.cpp b/BBGE/TileRender.cpp
index 8c18265..a7df141 100644
--- a/BBGE/TileRender.cpp
+++ b/BBGE/TileRender.cpp
@@ -62,6 +62,7 @@ void TileRender::onRender(const RenderState& rs) const
 	unsigned lastTexId = 0;
 
 	const bool renderExtras = renderBorders || RenderObject::renderCollisionShape;
+
 	const TileEffectData *prevEff = ((TileEffectData*)NULL)+1; // initial value is different from anything else
 
 	for(size_t i = 0; i < storage.tiles.size(); ++i)
@@ -183,20 +184,11 @@ void TileRender::onRender(const RenderState& rs) const
 				color *= getTagColor(tile.tag);
 
 				glColor4f(color.x, color.y, color.z, 1.0f);
+				core->getDefaultQuadBorderBuf()->apply();
 				glPointSize(16);
-				glBegin(GL_POINTS);
-					glVertex2f(0,0);
-				glEnd();
-
-				// TODO: move this to the IBO
+				glDrawArrays(GL_POINTS, 4, 1);
 				glLineWidth(2);
-				glBegin(GL_LINE_STRIP);
-					glVertex2f(0.5f, 0.5f);
-					glVertex2f(0.5f, -0.5f);
-					glVertex2f(-0.5f, -0.5f);
-					glVertex2f(-0.5f, 0.5f);
-					glVertex2f(0.5f, 0.5f);
-				glEnd();
+				glDrawArrays(GL_LINE_LOOP, 0, 4);
 			}
 		}
 
diff --git a/BBGE/VertexBuffer.cpp b/BBGE/VertexBuffer.cpp
index 4d3fdb6..ff87ea1 100644
--- a/BBGE/VertexBuffer.cpp
+++ b/BBGE/VertexBuffer.cpp
@@ -279,17 +279,17 @@ void DynamicGPUBuffer::drawElements(unsigned glmode, size_t n, size_t first) con
         glBindBufferARB(GL_ELEMENT_ARRAY_BUFFER_ARB, id);
     //}
 
-    void *p = id ? NULL : _h_data;
+    const unsigned short *p = (unsigned short*)(id ? NULL : _h_data);
     assert(p || id);
 
-    glDrawElements(glmode, n, GL_UNSIGNED_SHORT, p);
+    glDrawElements(glmode, n, GL_UNSIGNED_SHORT, p + first);
 }
 
 void DynamicGPUBuffer::initQuadVertices(const TexCoordBox& tc, unsigned access)
 {
     do
     {
-        float *p = (float*)beginWrite(GPUBUFTYPE_VEC2_TC, (4*4) * sizeof(float), access);
+        float *p = (float*)beginWrite(GPUBUFTYPE_VEC2_TC, (4*4 + 4) * sizeof(float), access);
         *p++ = -0.5f; *p++ = +0.5f;     // xy
 	    *p++ = tc.u1;   *p++ = tc.v1;  //   uv
 	    *p++ = +0.5f; *p++ = +0.5f;     // xy
@@ -298,6 +298,9 @@ void DynamicGPUBuffer::initQuadVertices(const TexCoordBox& tc, unsigned access)
 	    *p++ = tc.u2;   *p++ = tc.v2;  //   uv
 	    *p++ = -0.5f; *p++ = -0.5f;     // xy
 	    *p++ = tc.u1;   *p++ = tc.v2;  //   uv
+
+        for(size_t i = 0; i < 4; ++i)
+            *p++ = 0; // zero/center xy uv (uv isn't used)
     }
     while(!commitWrite());
 }
@@ -318,9 +321,10 @@ size_t DynamicGPUBuffer::initGridIndices_Triangles(size_t w, size_t h, bool inve
     const size_t quadsx = w - 1;
     const size_t quadsy = h - 1;
     const size_t quads = quadsx * quadsy;
+    const size_t border = 4; // for GL_LINE_LOOP
     do
     {
-        unsigned short *p = (unsigned short*)beginWrite(GPUBUFTYPE_U16, 6*quads * sizeof(short), access);
+        unsigned short *p = (unsigned short*)beginWrite(GPUBUFTYPE_U16, (6*quads + border) * sizeof(short), access);
 
         if(!invert)
         {