Vertex and index buffer

BlitzMax Forums/OpenGL Module/Vertex and index buffer

Ferret (Posted 2011) [#1]

I'm trying to understand the VBO but have a problem with mi test app. If i understand correctly i need to create a vertex buffer and a index buffer? Creating a vertex buffer seems to work but mi app crashes when i add a index buffer. '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Strict '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Global FE_VertexArray:Float[], FE_ColorArray:Float[], FE_NormalArray:Float[], FE_TextureArray:Float[] Global FE_Indices:Short[], FE_IndiceCount:Int=0 Global FE_VertexBuffer:Int, FE_IndexBuffer:Int Global FE_Framecounter:Float, FE_FrameTime:Float, FE_Framerate:Int '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' FE_Graphics() '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 'Vertex XYZ FE_VertexArray = FE_VertexArray + [-0.5,0.5,0.0, -0.5,-0.5,0.0, 0.5,-0.5,0.0] FE_VertexArray = FE_VertexArray + [-0.5,0.5,0.0, 0.5,-0.5,0.0, 0.5,0.5,0.0] glVertexPointer(3,GL_FLOAT,0,FE_VertexArray) glEnableClientState(GL_VERTEX_ARRAY) 'Color RGBA FE_ColorArray = FE_ColorArray + [0.0,1.0,0.0,0.0, 0.0,1.0,0.0,0.0, 0.0,1.0,0.0,0.0] FE_ColorArray = FE_ColorArray + [0.0,0.0,1.0,0.0, 0.0,0.0,1.0,0.0, 0.0,0.0,1.0,0.0] glColorPointer(4,GL_FLOAT,0,FE_ColorArray) 'add alpha glEnableClientState(GL_COLOR_ARRAY) 'Normal XYZ FE_NormalArray = FE_NormalArray + [FE_NX(-0.5,0.5,0.0),FE_NY(-0.5,0.5,0.0),FE_NZ(-0.5,0.5,0.0)] FE_NormalArray = FE_NormalArray + [FE_NX(-0.5,-0.5,0.0),FE_NY(-0.5,-0.5,0.0),FE_NZ(-0.5,-0.5,0.0)] FE_NormalArray = FE_NormalArray + [FE_NX(0.5,-0.5,0.0),FE_NY(0.5,-0.5,0.0),FE_NZ(0.5,-0.5,0.0)] FE_NormalArray = FE_NormalArray + [FE_NX(-0.5,0.5,0.0),FE_NY(-0.5,0.5,0.0),FE_NZ(-0.5,0.5,0.0)] FE_NormalArray = FE_NormalArray + [FE_NX(0.5,-0.5,0.0),FE_NY(0.5,-0.5,0.0),FE_NZ(0.5,-0.5,0.0)] FE_NormalArray = FE_NormalArray + [FE_NX(0.5,0.5,0.0),FE_NY(0.5,0.5,0.0),FE_NZ(0.5,0.5,0.0)] glNormalPointer(GL_FLOAT,0,FE_NormalArray) glEnableClientState(GL_NORMAL_ARRAY) 'Texture UV FE_TextureArray = FE_TextureArray + [0.0,1.0, 0.0,0.0, 1.0,0.0] FE_TextureArray = FE_TextureArray + [0.0,1.0, 1.0,0.0, 1.0,1.0] glTexCoordPointer(2,GL_FLOAT,0,FE_TextureArray) glEnableClientState(GL_TEXTURE_COORD_ARRAY) 'Indices FE_Indices = FE_Indices + [Short(0),Short(1),Short(2),Short(3),Short(4),Short(5)] FE_IndiceCount = 6 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 'VBO glgenbuffersARB(1,Varptr(FE_VertexBuffer)) glBindBufferARB(GL_ARRAY_BUFFER_ARB,FE_VertexBuffer) glBufferDataARB(GL_ARRAY_BUFFER_ARB,SizeOf(FE_VertexArray),FE_VertexArray,GL_STATIC_DRAW_ARB) 'IBO glGenBuffers(1,Varptr(FE_IndexBuffer)) glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,FE_IndexBuffer) glBufferData(GL_ELEMENT_ARRAY_BUFFER,SizeOf(FE_Indices),FE_Indices, GL_STATIC_DRAW) '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' glLoadIdentity() glTranslatef(0.0,0.0,-5.0) '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' While Not KeyHit(KEY_ESCAPE) glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT) 'glBindBufferARB(GL_ARRAY_BUFFER_ARB,FE_VertexBuffer) 'glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,FE_IndexBuffer) glDrawElements(GL_TRIANGLES,FE_IndiceCount,GL_UNSIGNED_SHORT,FE_Indices) GLDrawText("FPS:"+FE_FPS(),10,10) glFlush() Flip(False) PollSystem() Wend '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' End '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Function FE_Graphics(width:Int=800,height:Int=600,depth:Int=0,mode:Int=1,rate:Int=60) If depth = 0 Then depth = 32 If mode <> 0 Then depth = 0 If rate = 0 Then rate = 60 GLGraphics(width,height,depth,rate,GRAPHICS_BACKBUFFER | GRAPHICS_DEPTHBUFFER) glewInit() glHint(GL_PERSPECTIVE_CORRECTION_HINT,GL_NICEST) glMatrixMode(GL_PROJECTION) glLoadIdentity() gluPerspective(45.0,Float(width)/Float(600),1.0,1000.0) glMatrixMode(GL_MODELVIEW) glLoadIdentity() glClearDepth(1.0) glEnable(GL_CULL_FACE) glEnable(GL_DEPTH_TEST) glDepthFunc(GL_LEQUAL) glShadeModel(GL_SMOOTH) glEnable(GL_LIGHTING) glEnable(GL_LIGHT0) glEnable(GL_COLOR_MATERIAL) glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE) 'glEnable(GL_BLEND) 'glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA) glClearColor(0.0,0.0,0.0,0.0) glColor4f(1.0,1.0,1.0,0.0) End Function '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Function FE_NX:Float(vx:Float,vy:Int,vz:Int) Local d:Float = 1.0 / Sqr(vx*vx + vy*vy + vz*vz) vx = vx*d Return vx End Function '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Function FE_NY:Float(vx:Float,vy:Int,vz:Int) Local d:Float = 1.0 / Sqr(vx*vx + vy*vy + vz*vz) vy = vy*d Return vy End Function '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Function FE_NZ:Float(vx:Float,vy:Int,vz:Int) Local d:Float = 1.0 / Sqr(vx*vx + vy*vy + vz*vz) vz = vz*d Return vz End Function '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Function FE_FPS:Int() FE_Framecounter=FE_Framecounter+1 If FE_FrameTime=0 Then FE_FrameTime=MilliSecs() If FE_FrameTime+1001 <MilliSecs() Then FE_Framerate=FE_Framecounter FE_Framecounter=0 FE_FrameTime=MilliSecs() EndIf Return FE_Framerate End Function '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Last edited 2011

AdamRedwoods (Posted 2011) [#2]

It's not easy to tell without running the program, but at a quick glance you need to make sure: glBufferData( .. , Size, .., ..) where size is in BYTES. So a SHORT = Sizeof(short)*2, INT = Sizeof(int)*4, FLOAT = Sizeof(float)*4 , etc.

Ferret (Posted 2011) [#3]

I read another tutorial and no index buffer is used, only vertex buffer. How do i know i'm drawing from the vertex buffer? If i bind the buffer and draw using glDrawElements() and indices, am i drawing from the buffer? I did some test with 10K triangles and see no difference in performance.

Ferret (Posted 2011) [#4]

Got it to work :)