split Strand from Segmented; don't waste an entire RenderObject to store a single position

Aquaria/CMakeLists.txt

@@ -89,6 +89,7 @@ SET(AQUARIA_SRCS
     StatsAndAchievements.h
     SteamRender.cpp
     Strand.cpp
+    Strand.h
     StringBank_gen.h
     SubtitlePlayer.cpp
     SubtitlePlayer.h

Aquaria/ScriptedEntity.h

@@ -23,6 +23,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
 #include "CollideEntity.h"
 #include "Segmented.h"
+#include "Strand.h"
 #include "Particles.h"
 #include "Scriptable.h"
 

Aquaria/Segmented.h

@@ -22,7 +22,6 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #define SEGMENTED_H
 
 #include "../BBGE/Quad.h"
-#include "VertexBuffer.h"
 
 class Segmented
 {
@@ -44,16 +43,5 @@ protected:
 	std::vector<RenderObject *> segments;
 };
 
-class Strand : public RenderObject, public Segmented
-{
-public:
-	Strand(const Vector &position, size_t segs, size_t dist=32);
-	void destroy() OVERRIDE;
-protected:
-	void onUpdate(float dt) OVERRIDE;
-	void onRender(const RenderState& rs) const OVERRIDE;
-
-	DynamicGPUBuffer gpubuf;
-};
 
 #endif

Aquaria/Strand.cpp

@@ -18,45 +18,53 @@ You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
-#include "Segmented.h"
+#include "Strand.h"
 #include "RenderBase.h"
 
-Strand::Strand(const Vector &position, size_t segs, size_t dist)
-	: RenderObject(), Segmented(dist, dist)
+Strand::Strand(const Vector &position, size_t segs, float dist)
+	: RenderObject()
+	, points(segs)
 	, gpubuf(GPUBUF_DYNAMIC | GPUBUF_VERTEXBUF)
+	, dist(dist)
 {
 	assert(segs);
 	cull = false;
-	segments.resize(segs);
-	for (size_t i = 0; i < segments.size(); i++)
-	{
-		// FIXME: This is super costly to waste an entire RenderObject just to store a position.
-		segments[i] = new RenderObject;
-	}
-	initSegments(position);
+	for (size_t i = 0; i < segs; i++)
+		points[i] = position;
 }
 
-void Strand::destroy()
+void Strand::updatePoints()
 {
-	RenderObject::destroy();
-	for (size_t i = 0; i < segments.size(); i++)
+	Vector last = position;
+	const float distsq = sqr(dist);
+	const size_t N = points.size();
+	for(size_t i = 0; i < N; ++i)
 	{
-		segments[i]->destroy();
-		delete segments[i];
+		Vector pt = points[i];
+		const Vector diff = last - pt;
+		last = pt;
+		const float sqrLength = diff.getSquaredLength2D();
+
+		if (sqrLength < distsq)
+			continue;
+
+		Vector useDiff = diff;
+		useDiff.setLength2D(dist);
+		Vector reallyUseDiff = diff - useDiff;
+		points[i] = pt + reallyUseDiff;
 	}
-	segments.clear();
 }
 
 void Strand::onUpdate(float dt)
 {
 	RenderObject::onUpdate(dt);
-	updateSegments(position);
+	updatePoints();
 
-	const size_t numSegments = segments.size();
+	const size_t N = points.size();
 
 	do
 	{
-		const size_t bytes = (numSegments+1) * 6 * sizeof(float);
+		const size_t bytes = (N+1) * 6 * sizeof(float); // +1 for the initial origin vertex
 		float *p = (float*)gpubuf.beginWrite(GPUBUFTYPE_VEC2_RGBA, bytes, GPUACCESS_DEFAULT);
 
 		// Note: We're rewriting all of the vertex data here.
@@ -64,9 +72,9 @@ void Strand::onUpdate(float dt)
 		// but currently this is to keep buffer layouts simple.
 
 		const float factor = 1.0f / 50.0f;
-		const size_t colorLimit = numSegments<50 ? numSegments : 50;
+		const size_t colorLimit = N<50 ? N : 50;
 		const Vector falloff = color * factor;
-		const float falloffAlpha = 1.0f / float(numSegments);
+		const float falloffAlpha = 1.0f / float(N);
 		float a = 1.0f;
 		Vector c = color;
 
@@ -82,8 +90,8 @@ void Strand::onUpdate(float dt)
 		size_t i;
 		for(i = 0; i < colorLimit; ++i)
 		{
-			*p++ = segments[i]->position.x;
-			*p++ = segments[i]->position.y;
+			*p++ = points[i].x;
+			*p++ = points[i].y;
 
 			*p++ = c.x;
 			*p++ = c.y;
@@ -93,10 +101,10 @@ void Strand::onUpdate(float dt)
 			c -= falloff;
 			a -= falloffAlpha;
 		}
-		for( ; i < numSegments; ++i)
+		for( ; i < N; ++i)
 		{
-			*p++ = segments[i]->position.x;
-			*p++ = segments[i]->position.y;
+			*p++ = points[i].x;
+			*p++ = points[i].y;
 
 			*p++ = 0.0f;
 			*p++ = 0.0f;
@@ -115,5 +123,5 @@ void Strand::onRender(const RenderState& rs) const
 	glLineWidth(1);
 
 	gpubuf.apply();
-	glDrawArrays(GL_LINE_STRIP, 0, GLsizei(segments.size() + 1));
+	glDrawArrays(GL_LINE_STRIP, 0, GLsizei(points.size() + 1));
 }

Aquaria/Strand.h

@@ -0,0 +1,24 @@
+#ifndef SEGMENTED_STRAND_H
+#define SEGMENTED_STRAND_H
+
+#include "RenderObject.h"
+#include "VertexBuffer.h"
+
+class Strand : public RenderObject
+{
+public:
+	Strand(const Vector &position, size_t segs, float dist=32);
+protected:
+	void onUpdate(float dt) OVERRIDE;
+	void onRender(const RenderState& rs) const OVERRIDE;
+
+private:
+	void updatePoints();
+
+	DynamicGPUBuffer gpubuf;
+	std::vector<Vector> points;
+	float dist;
+};
+
+
+#endif