Blobby Objects in OpenGL

BlitzMax Forums/BlitzMax Tutorials/Blobby Objects in OpenGL

ImaginaryHuman (Posted 2005) [#1]

Hi folks. Recently I posted a tutorial on how to render fast 2D blobby objects in BlitzMax in realtime, in this thread: http://www.blitzbasic.com/Community/posts.php?topic=45716 I decided to release a more complex version of my blob routines that uses lots of direct OpenGL and almost no Max2D commands. This version loads and needs four pre-rendered blob-field images (examples included below) which are 512x512 grayscale RGB images in PNG format. It also loads a `filler` image texture which is a 256x256 color RGB image in PNG format (example also included below). This version can actually load 4 different blob-field images at once so you can experiment with using the same one four times or more than one kind. These blob images are based on a standard blob field as generated by the included `DrawSquare512` and `DrawBall512` programs. Using those programs you can generate the basic blob field - I use a screengrab to save them to disk as PNG's. They have been loaded into image processing graphics software and manipulated, for example applying a simple `twist/twirl/spin` effect. There are many effects you could apply, for example a wave or ripple effect. Effects that move the pixels around, preserving the basic content, are the best and still produce a blob effect. This version doesn't include animation but I have since implemented an animated version that loads 20 frames of a cyclic animation, produced with image processing software applied to the standard blob field image with a rippling wave effect. You can move the mouse around to move all of the blobs. Positioning the mouse near the lower right at about 3/4 of the width and height of the screen produces a fairly stationary shape. I haven't tidied up the code too much and there is some old/optional bits that are commented out. There's also some extraneous OpenGL calls near the start that may not be needed - but I found that the `default` state of the OpenGL machine was different on different platforms, so I'm just making sure things are set up right. For me this runs okay on an iMac 1GHz G4 with an nVidea GeForce 4MX at around 30fps with vblank synching. You may need a comparable gfx card performance (750 million texels/second or so at least, I would guess - the GeForce 4MX is 1 billion texels/second). Feel free to use this for whatever purpose you like, no strings attached. I hope it will work on your system with no problems. These are four different blob field images that you will need. Currently the code will load all four but you could change it to load only one repeatedly. The reason I applied a `twist` effect to the blob field is that it produces much smaller blobs and is still smooth. It took a lot of experimentation to come up with this effect. You also will need this filler texture image (or something similar). Any 256x256 PNG will do but it should be RGB not RGBA (no alpha). This image is just faded out at the edges so as to smoothly blend together. Other images that I found interesting were based on clouds or fractals. This is the main program and is freeware. I apologize for any untidyness or `procedural coding` technique, it's not very object-oriented. The blob images are uploaded as GL_ALPHA textures, which are just one 8-bit color component per pixel. This saves on storage space, and allows use of particular blend modes later on. The filler image is regular color texture. The rendering code within the main loop - you can comment out whole sections if you'd like to see the effect that each part has. There are also some flags at the top of the code to turn certain things on and off. You can also modify the rotation angle increments and the kind of colors that are produced at other points in the code. Strict Const wid:Int=1024 Const hig:Int=768 Const objs:Int=26 Const moveobjs:Int=True Const rotobjs:Int=True Const background:Int=True Const rotatecolor:Int=True Local ballsize:Int=512 'based on 512x512 image Local ballsizehalf:Int=ballsize Shr 1 Local ballsize2:Int=256 'based on 256x256 color image Local ballsizehalf2:Int=ballsize2 Shr 1 AutoMidHandle True Local px1:TPixmap[4] px1[0]=LoadPixmap("BigBall48.png") '1 to 22 RGB - 512x512 grayscale px1[0]=ResizePixmap(px1[0],ballsize,ballsize) 'Make sure of size px1[0]=ConvertPixmap(px1[0],PF_RGBA8888) 'Make it 4 bytes per pixel px1[1]=LoadPixmap("BigBall47.png") '1 to 22 RGB - 512x512 grayscale px1[1]=ResizePixmap(px1[1],ballsize,ballsize) 'Make sure of size px1[1]=ConvertPixmap(px1[1],PF_RGBA8888) 'Make it 4 bytes per pixel px1[2]=LoadPixmap("BigBall46.png") '1 to 22 RGB - 512x512 grayscale px1[2]=ResizePixmap(px1[2],ballsize,ballsize) 'Make sure of size px1[2]=ConvertPixmap(px1[2],PF_RGBA8888) 'Make it 4 bytes per pixel px1[3]=LoadPixmap("BigBall01.png") '1 to 22 RGB - 512x512 grayscale px1[3]=ResizePixmap(px1[3],ballsize,ballsize) 'Make sure of size px1[3]=ConvertPixmap(px1[3],PF_RGBA8888) 'Make it 4 bytes per pixel Local px2:TPixmap=LoadPixmap("Ball48.png")'"BigBallC02.png") '1 to 14 RGB - 512x512 color px2=ResizePixmap(px2,ballsize2,ballsize2) 'Make sure of size px2=ConvertPixmap(px2,PF_RGBA8888) 'Make it 4 bytes per pixel bglCreateContext(wid,hig,32,0,BGL_BACKBUFFER|BGL_FULLSCREEN) glViewport(0,0,wid,hig) glMatrixMode (GL_PROJECTION) glLoadIdentity glOrtho(0,wid,hig,0,-1,1) 'gluOrtho2D(0,wid,0,hig) glMatrixMode(GL_TEXTURE) glLoadIdentity glMatrixMode(GL_MODELVIEW) glLoadIdentity glClear(GL_COLOR_BUFFER_BIT) bglSwapBuffers glClear(GL_COLOR_BUFFER_BIT) bglSwapBuffers glDisable(GL_DEPTH_TEST) glDisable(GL_STENCIL_TEST) glDisable(GL_ALPHA_TEST) glDisable(GL_SCISSOR_TEST) glDisable(GL_CULL_FACE) 'glDisable(GL_POLYGON_SMOOTH) glEnable(GL_POLYGON_SMOOTH) 'glDisable(GL_LOGIC_OP) glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_TRUE) 'bglSetSwapInterval(0) 'no vbl sync GLDisable(GL_DITHER) glTexEnvi(GL_TEXTURE_ENV,GL_TEXTURE_ENV_MODE,GL_MODULATE)'GL_DECAL/GL_BLEND glPolygonMode(GL_FRONT_AND_BACK,GL_FILL) 'face glDrawBuffer(GL_BACK) glClearColor(0,0,0,0) glColor4b($FF,$FF,$FF,$FF) SeedRnd(MilliSecs()) 'Create bank space to store an alpha buffer 'Local bnk:TBank=CreateBank(ballsize*ballsize) 'to store alpha image 'Local where:Byte Ptr=BankBuf(bnk) ''Create an alpha buffer Local pxp:Byte Ptr[4] pxp[0]=PixmapPixelPtr(px1[0],0,0) pxp[1]=PixmapPixelPtr(px1[1],0,0) pxp[2]=PixmapPixelPtr(px1[2],0,0) pxp[3]=PixmapPixelPtr(px1[3],0,0) Local pxp2:Byte Ptr=PixmapPixelPtr(px2,0,0) Local pitch:Int[4] pitch[0]=PixmapPitch(px1[0]) pitch[1]=PixmapPitch(px1[1]) pitch[2]=PixmapPitch(px1[2]) pitch[3]=PixmapPitch(px1[3]) Local pitch2:Int=PixmapPitch(px2) 'Local aimage:Byte Ptr=where 'to create alpha by itself Local aimage:Byte Ptr[4] aimage[0]=pxp[0]+3 'to create alpha within RGBA aimage[1]=pxp[1]+3 'to create alpha within RGBA aimage[2]=pxp[2]+3 'to create alpha within RGBA aimage[3]=pxp[3]+3 'to create alpha within RGBA Local aimage2:Byte Ptr=pxp2+3 'to create alpha within RGBA For Local yy:Int=0 To ballsize-1 Local yloc:Int[4] yloc[0]=yy*pitch[0] yloc[1]=yy*pitch[1] yloc[2]=yy*pitch[2] yloc[3]=yy*pitch[3] For Local xx:Int=0 To ballsize-1 (aimage[0])[xx Shl 2]=$FF'pxp[yloc[0]+(xx Shl 2)] 'copy the red component into the alpha buffer (aimage[1])[xx Shl 2]=$FF'pxp[yloc[1]+(xx Shl 2)] 'copy the red component into the alpha buffer (aimage[2])[xx Shl 2]=$FF'pxp[yloc[2]+(xx Shl 2)] 'copy the red component into the alpha buffer (aimage[3])[xx Shl 2]=$FF'pxp[yloc[3]+(xx Shl 2)] 'copy the red component into the alpha buffer If xx<ballsize2 And yy<ballsize2 Then aimage2[xx Shl 2]=$18'pxp[yloc[0]+(xx Shl 2)] 'copy the red component into the alpha buffer Next aimage[0]:+pitch[0]'256 aimage[1]:+pitch[1]'256 aimage[2]:+pitch[2]'256 aimage[3]:+pitch[3]'256 aimage2:+pitch2'256 Next 'glPixelStorei(GL_UNPACK_ALIGNMENT,1) 'bytes for stand-alone alpha glPixelStorei(GL_UNPACK_ALIGNMENT,4) 'ints for RGBA with alpha glPixelStorei(GL_UNPACK_ROW_LENGTH,ballsize) 'How many pixels in a row glPixelStorei(GL_UNPACK_SWAP_BYTES,GL_FALSE) glPixelStorei(GL_UNPACK_LSB_FIRST,GL_FALSE) glPixelStorei(GL_UNPACK_SKIP_PIXELS,0) glPixelStorei(GL_UNPACK_SKIP_ROWS,0) glPixelTransferf(GL_RED_SCALE,1.0) glPixelTransferf(GL_RED_BIAS,0.0) glPixelTransferf(GL_GREEN_SCALE,1.0) glPixelTransferf(GL_GREEN_BIAS,0.0) glPixelTransferf(GL_BLUE_SCALE,1.0) glPixelTransferf(GL_BLUE_BIAS,0.0) glPixelTransferf(GL_ALPHA_SCALE,1.0) glPixelTransferf(GL_ALPHA_BIAS,0.0) glPixelTransferi(GL_MAP_COLOR,GL_FALSE) glPixelTransferi(GL_MAP_STENCIL,GL_FALSE) 'Define blob images Global name:Int[4] For Local Counter:Int=0 To 3 name[Counter]=0 glGenTextures(1,VarPtr(name[Counter])) glBindTexture(GL_TEXTURE_2D,name[Counter]) 'glTexImage2D(GL_TEXTURE_2D,0,GL_ALPHA,ballsize,ballsize,0,GL_ALPHA,GL_UNSIGNED_BYTE,where) 'Renderable alpha image glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,ballsize,ballsize,0,GL_RGBA,GL_UNSIGNED_BYTE,pxp[Counter]) 'Renderable RGBA image glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP) 'must come after the glBindTexture() glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP) glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR) glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR) Next 'Define color image glPixelStorei(GL_UNPACK_ROW_LENGTH,ballsize2) 'How many pixels in a row Global name2:Int=0 glGenTextures(1,VarPtr(name2)) glBindTexture(GL_TEXTURE_2D,name2) glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,ballsize2,ballsize2,0,GL_RGBA,GL_UNSIGNED_BYTE,pxp2) 'Renderable RGBA image glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP) 'must come after the glBindTexture() glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP) glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR) glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR) 'For objects and their color Local objx:Float[objs] Local objy:Float[objs] Local xadd:Float[objs] Local yadd:Float[objs] Local colr:Byte[objs+3] Local colg:Byte[objs+3] Local colb:Byte[objs+3] Local spin:Float[objs] Local angle:Float[objs] Local ohalf:Int=objs/2 For Local Counter:Int=0 To ohalf-1 objx[Counter]=Rand(0,wid-21-ballsizehalf)+10-(ballsizehalf Shr 1) objy[Counter]=Rand(0,hig-21-ballsizehalf)+10-(ballsizehalf Shr 1) xadd[Counter]=Rnd(0,0.75)-Rnd(0,0.75) yadd[Counter]=Rnd(0,0.75)-Rnd(0,0.75) If Rand(0,1)=1 colr[Counter]=Rand(0,255) colg[Counter]=Rand(0,255) colb[Counter]=Rand(0,255) Else colr[Counter]=$FF colg[Counter]=$FF colb[Counter]=$FF EndIf If rotobjs spin[Counter]=0.5'Rnd(1.0,1.5) 'If Rand(0,1)=1 Then spin[Counter]=-spin[Counter] angle[Counter]=Rnd(0,360.0) EndIf Next For Local Counter:Int=0 To 2 'for drawing extra colors for ball textures colr[objs+Counter]=Rand(0,255) colg[objs+Counter]=Rand(0,255) colb[objs+Counter]=Rand(0,255) Next For Local Counter:Int=ohalf To objs-1 objx[Counter]=objx[Counter-ohalf]'Rand(0,619-ballsize)+10 objy[Counter]=objy[Counter-ohalf]'Rand(0,459-ballsize)+10 xadd[Counter]=xadd[Counter-ohalf]'Rnd(0,0.5)-Rnd(0,0.5) yadd[Counter]=yadd[Counter-ohalf]'Rnd(0,0.5)-Rnd(0,0.5) If Rand(0,1)=1 colr[Counter]=Rand(0,255) colg[Counter]=Rand(0,255) colb[Counter]=Rand(0,255) Else colr[Counter]=$FF colg[Counter]=$FF colb[Counter]=$FF EndIf If rotobjs spin[Counter]=0.5'Rnd(1.0,1.5) 'If Rand(0,1)=1 Then spin[Counter]=-spin[Counter] angle[Counter]=Rnd(0,360.0) EndIf Next For Local Counter:Int=0 To 2 'for drawing extra colors for ball textures colr[objs+Counter]=Rand(0,255) colg[objs+Counter]=Rand(0,255) colb[objs+Counter]=Rand(0,255) Next 'For colorization of display Const keach:Int=256 'size of background textures Const ksize:Int=((wid/keach)+1)*((hig/keach)+3) Const krow:Int=(wid/keach)+1 Local kullar:Byte[ksize] Local kullag:Byte[ksize] Local kullab:Byte[ksize] For Local Counter:Int=0 To ksize-1 If background kullar[Counter]=Rand($11,$28) kullag[Counter]=Rand($11,$28) kullab[Counter]=Rand($11,$28) Else kullar[Counter]=0 kullag[Counter]=0 kullab[Counter]=0 EndIf Next Global mx:Int Global my:Int Repeat 'Move objects If moveobjs For Local Counter:Int=0 To objs-1 objx[Counter]:+xadd[Counter] If objx[Counter]>wid-10-ballsizehalf Or objx[Counter]<10-ballsizehalf xadd[Counter]=-xadd[Counter] objx[Counter]:+xadd[Counter] EndIf Next For Local Counter:Int=0 To objs-1 objy[Counter]:+yadd[Counter] If objy[Counter]>hig-10-ballsizehalf Or objy[Counter]<10-ballsizehalf yadd[Counter]=-yadd[Counter] objy[Counter]:+yadd[Counter] EndIf Next EndIf For Local Counter:Int=0 To objs-1 angle[Counter]:+spin[Counter] Mod 360 Next mx:Int=Int(MouseX())-ballsizehalf my:Int=Int(MouseY())-ballsizehalf glColor4b($FF,$FF,$FF,$FF) glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_TRUE) glClear(GL_COLOR_BUFFER_BIT) 'cls glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) glEnable(GL_BLEND) glBlendFunc(GL_SRC_ALPHA,GL_ONE) glEnable(GL_TEXTURE_2D) glShadeModel(GL_SMOOTH) glEnable(GL_POLYGON_SMOOTH) glMatrixMode(GL_MODELVIEW) Local txtr:Int=0 'what texture to use? For Local Counter:Int=0 To objs-1 If Counter Mod 2=0 glBindTexture(GL_TEXTURE_2D,name[txtr]) 'select renderable image texture for drawing txtr:+1 txtr:Mod 4 EndIf glLoadIdentity() glTranslatef(objx[Counter]+ballsizehalf,objy[Counter]+ballsizehalf,0) glRotatef(angle[Counter],0,0,1) glTranslatef(-ballsizehalf,-ballsizehalf,0) glBegin GL_QUADS glColor3b(colr[Counter],colg[Counter],colb[Counter]) glTexCoord2f(0,0); glVertex2f((wid/2)-mx,(hig/2)-my)'glVertex2f(objx[Counter],objy[Counter]) glColor3b(colr[Counter+1],colg[Counter+1],colb[Counter+1]) glTexCoord2f(1,0); glVertex2f((wid/2)-mx+ballsize,(hig/2)-my)'glVertex2f(objx[Counter]+ballsize,objy[Counter]) glColor3b(colr[Counter+2],colg[Counter+2],colb[Counter+2]) glTexCoord2f(1,1); glVertex2f((wid/2)-mx+ballsize,(hig/2)-my+ballsize)'glVertex2f(objx[Counter]+ballsize,objy[Counter]+ballsize) glColor3b(colr[Counter+3],colg[Counter+3],colb[Counter+3]) glTexCoord2f(0,1); glVertex2f((wid/2)-mx,(hig/2)-my+ballsize)'objx[Counter],objy[Counter]+ballsize) glEnd Next glLoadIdentity() glTranslatef(mx+ballsizehalf,my+ballsizehalf,0) glRotatef(angle[0],0,0,1) glTranslatef(-ballsizehalf,-ballsizehalf,0) glBindTexture(GL_TEXTURE_2D,name[2]) glBegin GL_QUADS glTexCoord2f(0,0); glColor3b($FF,$FF,$FF); glVertex2f(0,0) glTexCoord2f(1,0); glColor3b($FF,$FF,$FF); glVertex2f(ballsize,0) glTexCoord2f(1,1); glColor3b($FF,$FF,$FF); glVertex2f(ballsize,ballsize) glTexCoord2f(0,1); glColor3b($FF,$FF,$FF); glVertex2f(0,ballsize) glEnd glLoadIdentity() glDisable(GL_TEXTURE_2D) glDisable(GL_BLEND) glDisable(GL_POLYGON_SMOOTH) 'Image currently become blobs when intensity is 255, add $40 (multiplied by 2 is $80) to make blobs begin at 128 intensity glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) glEnable(GL_BLEND) glBlendFunc(GL_SRC_ALPHA,GL_ONE) glColor4b($40,$40,$40,$40) glBegin GL_QUADS 'glColor3b($FF,0,0) glVertex2f(0,0) 'glColor3b(0,$FF,0) glVertex2f(wid,0) 'glColor3b($FF,0,$FF) glVertex2f(wid,hig) 'glColor3b(0,0,$FF) glVertex2f(0,hig) glEnd glDisable(GL_BLEND) 'Saturate to make the edges sharp glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) glEnable(GL_BLEND) glBlendFunc(GL_SRC_ALPHA_SATURATE,GL_DST_COLOR) glColor4b(0,0,0,$FF) For Local Counter:Int=1 To 3 glBegin GL_QUADS 'glColor3b($FF,0,0) glVertex2f(0,0) 'glColor3b(0,$FF,0) glVertex2f(wid,0) 'glColor3b($FF,0,$FF) glVertex2f(wid,hig) 'glColor3b(0,0,$FF) glVertex2f(0,hig) glEnd Next glDisable(GL_BLEND) 'Invert the image, draw background textures and add color glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) glEnable(GL_BLEND) glBlendFunc(GL_ONE_MINUS_DST_COLOR,GL_ONE_MINUS_DST_COLOR) glShadeModel(GL_SMOOTH) 'glColor3b($FF,$FF,$FF) glEnable(GL_TEXTURE_2D) Local Counter:Int=0 For Local yy:Int=0 To hig-1 Step keach For Local xx:Int=0 To wid-1 Step keach glBegin GL_QUADS glColor3b(kullar[Counter],kullag[Counter],kullab[Counter]) glTexCoord2i(0,0); glVertex2f(xx,yy) glColor3b(kullar[Counter+1],kullag[Counter+1],kullab[Counter+1]) glTexCoord2i(0,1); glVertex2f(xx+keach,yy) glColor3b(kullar[Counter+1+krow],kullag[Counter+1+krow],kullab[Counter+1+krow]) glTexCoord2i(1,1); glVertex2f(xx+keach,yy+keach) glColor3b(kullar[Counter+krow],kullag[Counter+krow],kullab[Counter+krow]) glTexCoord2i(1,0); glVertex2f(xx,yy+keach) glEnd Counter:+1 Next Counter:+1 Next glDisable(GL_TEXTURE_2D) glDisable(GL_BLEND) 'Brighten the image, too dark due to previous addition of brightness glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) glEnable(GL_BLEND) glBlendFunc(GL_DST_COLOR,GL_DST_COLOR) glColor4b($FF,$FF,$FF,$FF) For Local Counter:Int=1 To 3 glBegin GL_QUADS 'glColor3b($FF,0,0) glVertex2f(0,0) 'glColor3b(0,$FF,0) glVertex2f(wid,0) 'glColor3b($FF,0,$FF) glVertex2f(wid,hig) 'glColor3b(0,0,$FF) glVertex2f(0,hig) glEnd Next glDisable(GL_BLEND) 'Draw color objects for fill glColor4b($FF,$FF,$FF,$FF) glColorMask(GL_TRUE,GL_TRUE,GL_TRUE,GL_FALSE) glEnable(GL_BLEND) glBlendFunc(GL_SRC_ALPHA,GL_ONE) glEnable(GL_TEXTURE_2D) glShadeModel(GL_SMOOTH) glEnable(GL_POLYGON_SMOOTH) glBindTexture(GL_TEXTURE_2D,name2) 'select renderable image texture for drawing glMatrixMode(GL_MODELVIEW) For Local Counter:Int=0 To objs-1 glLoadIdentity() glTranslatef(objx[Counter]+ballsizehalf,objy[Counter]+ballsizehalf,0) If rotatecolor Then glRotatef(angle[Counter],0,0,1) glTranslatef(-ballsizehalf2,-ballsizehalf2,0) glBegin GL_QUADS glColor3b(colr[Counter],colg[Counter],colb[Counter]) glTexCoord2f(0,0); glVertex2f((wid/2)-mx,(hig/2)-my) glColor3b(colr[Counter+1],colg[Counter+1],colb[Counter+1]) glTexCoord2f(1,0); glVertex2f((wid/2)-mx+ballsize2,(hig/2)-my) glColor3b(colr[Counter+2],colg[Counter+2],colb[Counter+2]) glTexCoord2f(1,1); glVertex2f((wid/2)-mx+ballsize2,(hig/2)-my+ballsize2) glColor3b(colr[Counter+3],colg[Counter+3],colb[Counter+3]) glTexCoord2f(0,1); glVertex2f((wid/2)-mx,(hig/2)-my+ballsize2) glEnd Next glLoadIdentity() glDisable(GL_TEXTURE_2D) glDisable(GL_POLYGON_SMOOTH) glDisable(GL_BLEND) bglSwapBuffers ' Repeat;Until KeyHit(KEY_SPACE) Until KeyHit(KEY_ESCAPE) End This is the program you use to generate a basic blob field image, freeware also. This one generates circular blob fields (standard blobby objects). This produces blobs that form nicely curved outlines as standard. The commented-out code at the end adds various extra little effects to it (just experiments). Strict Local ballsize:Int=512 Local ballsizehalf:Int=ballsize/2 Local balldivider:Float 'cant figure out formulae for what this needs to be dynamically, so hardwired If ballsize=128 Then balldivider:Float=64 If ballsize=256 Then balldivider:Float=256 If ballsize=512 Then balldivider:Float=1024 Graphics 800,600,0 Cls DrawText "Generating ball image...",10,10 Flip SetClsColor $FF,$FF,$FF Cls SetColor 0,0,0 DrawRect 0,0,ballsize,ballsize SetColor $FF,$FF,$FF For Local r:Float=1 To ballsize-1 Step 0.5 Local level:Float=r 'Numbers ranging from 0 to 255 level:*level 'Square the level (radius) level=level/balldivider SetColor level,level,level 'Proper blobby object 'SetColor r,r,r 'Linear blobs DrawOval r/2,r/2,ballsize-r,ballsize-r Next SeedRnd(MilliSecs()) 'glEnable(GL_LINE_SMOOTH) 'SetBlend LIGHTBLEND 'SetColor $08,$08,$08 'For Local l:Int=0 To 500 ' Local angle:Float=Rnd(0,360.0) ' DrawLine ballsizehalf,ballsizehalf,ballsizehalf+(ballsizehalf*Cos(angle)),ballsizehalf+(ballsizehalf*Sin(angle)),False '' DrawLine ballsizehalf+(Rnd(ballsizehalf)*Cos(angle)),ballsizehalf+(Rnd(ballsizehalf)*Sin(angle)),ballsizehalf+(ballsizehalf*Cos(angle)),ballsizehalf+(ballsizehalf*Sin(angle)),False '' Plot ballsizehalf+(Rnd(ballsizehalf)*Cos(angle)),ballsizehalf+(Rnd(ballsizehalf)*Sin(angle)) '' DrawRect Rnd(ballsize),Rnd(ballsize),Rnd(50),Rnd(50) '' DrawOval Rnd(ballsize),Rnd(ballsize),Rnd(50),Rnd(50) '' DrawLine Rnd(ballsize),Rnd(ballsize),Rnd(ballsize),Rnd(ballsize) 'Next Flip Repeat Until KeyHit(KEY_ESCAPE) And this one generates a blob field image based on squares - this produces a very interesting bubbling blob effect of many different shapes and sizes (of course freeware too). I have never seen this done before so maybe I can lay claim to actually inventing this! Since it is based on squares you might think it couldn't produce a blob shape, but it actually does, and goes further to add a lot of variety. Strict Local ballsize:Int=512 Local ballsizehalf:Int=ballsize/2 Local balldivider:Float 'cant figure out formulae for what this needs to be dynamically, so hardwired If ballsize=128 Then balldivider:Float=64 If ballsize=256 Then balldivider:Float=256 If ballsize=512 Then balldivider:Float=1024 Graphics 800,600,0 Cls DrawText "Generating ball image...",10,10 Flip SetClsColor $FF,$FF,$FF Cls SetColor 0,0,0 DrawRect 0,0,ballsize,ballsize SetColor $FF,$FF,$FF For Local r:Float=1 To ballsize-1 Step 0.5 Local level:Float=r 'Numbers ranging from 0 to 255 level:*level 'Square the level (radius) level=level/balldivider SetColor level,level,level 'Proper blobby object 'SetColor r,r,r 'Linear blobs DrawRect r/2,r/2,ballsize-r,ballsize-r Next SeedRnd(MilliSecs()) 'glEnable(GL_LINE_SMOOTH) 'SetBlend LIGHTBLEND 'SetColor $08,$08,$08 'For Local l:Int=0 To 500 ' Local angle:Float=Rnd(0,360.0) ' DrawLine ballsizehalf,ballsizehalf,ballsizehalf+(ballsize*Cos(angle)),ballsizehalf+(ballsize*Sin(angle)),False '' DrawLine ballsizehalf+(Rnd(ballsizehalf)*Cos(angle)),ballsizehalf+(Rnd(ballsizehalf)*Sin(angle)),ballsizehalf+(ballsizehalf*Cos(angle)),ballsizehalf+(ballsizehalf*Sin(angle)),False '' Plot ballsizehalf+(Rnd(ballsizehalf)*Cos(angle)),ballsizehalf+(Rnd(ballsizehalf)*Sin(angle)) '' DrawRect Rnd(ballsize),Rnd(ballsize),Rnd(50),Rnd(50) '' DrawOval Rnd(ballsize),Rnd(ballsize),Rnd(50),Rnd(50) '' DrawLine Rnd(ballsize),Rnd(ballsize),Rnd(ballsize),Rnd(ballsize) 'Next Flip Repeat Until KeyHit(KEY_ESCAPE) The effect should end up looking something like this: All these files are free for your use in whatever manner. :-)

BlitzSupport (Posted 2005) [#2]

Thanks AD, that's very generous, but I'm getting the same problem here that occurred with the old Blobs + OpenGL demo -- the screen's all black... :(

Koekelas (Posted 2005) [#3]

I'm still experimenting whit the previous examples and here you are whit yet another excellent tutorial. I'm glad you decided to continue working on this. Thank you very much AngleDaniel. Btw, it works fine here. Mac power I guess. Nicolas.

ImaginaryHuman (Posted 2005) [#4]

James - I will try to figure out what might be wrong, but I can't really test it if it's running fine for me here. Are you on a Mac too?

Sarge (Posted 2005) [#5]

AngelDaniel i have the same problem on WindowsXP it seems to be a dark backround i can hardly see the objects. I tried glDrawBuffer(GL_Front) i can see it like that but all messed up.

Koekelas (Posted 2005) [#6]

AngelDaniel, can you tell us how you did that twist effect on the first three metaballs? Nicolas.

LAB[au] (Posted 2005) [#7]

I have the same problem as Sarge... on Win2K (Geforce FX5900) I can see only colored "ball48.png" textures rotating, but very dark and nothing else. Strange...

BlitzSupport (Posted 2005) [#8]

Angel, that was on XP, so I guess you can't do much. It does work on the Mac -- slow in 1024 x 768, but decent in 640 x 480. (I don't know enough 'raw' OpenGL to debug it myself on XP!)

ImaginaryHuman (Posted 2005) [#9]

Oh ok. I can't help too much with the problem if it's produced only on the PC. Perhaps some other handy OpenGL-familiar coders can help to find the problem. Otherwise you could just go through and comment out various sections and see if you can find which part is wrong. I'm glad it works okay on the Macs. Since OpenGL is *supposed* to be standard on all implementations, and this doesn't use any extra extensions, I would've thought it should work the same on the PC. But you know how Microsoft can be ;-D Having said that the software rendered on my iBook has different default state than the hardware driver on my iMac. Nicolas - the twist is just your average `twirl` or `spin` image-processing effect. Load the standard plain square image into whatever image processing software, for example Gimp or Photoshop, and just apply the filter to it. Simple as that. Other filters of interest for effects are ripple and wave effects.

Koekelas (Posted 2005) [#10]

Thanks AngelDaniel. I'm not that handy whit Gimp. I combined the two tutorials and I came up whit more or less the same result as above but whit much lesser OpenGL. Nicolas.

ImaginaryHuman (Posted 2005) [#11]

Understandable. The second program in the original tutorial more or less achieved all the same steps in the pipeline, it would just be a matter of loading in a square-based blob image and moving the stuff around.