Sounds super interesting! I will check this out tomorrow from my 3D-enabled cpu :P
As far as I know there isn't anyone doing particles for away3D. -Pete On Tue, Jun 14, 2011 at 7:37 PM, McFunkypants <goo...@orangeview.net> wrote: > Woo hoo! I have been successful in implementing a fully GPU animated > particle system (60fps with 40,000 particles each moving in different > directions, rotating and scaling larger while fading out) that uses > AGAL for all simulation - not the CPU. > http://www.mcfunkypants.com/molehill/particles/ > > Right now it does NOT use away3d classes at all for efficiency. It is > all hand coded as3. Forgive my laziness - I might try to incorporate > it into away3d once I finish my book on Molehill next month. But just > for reference, the good news is that I can confirm beyond any shadow > of a doubt that the "all done in AGAL + batched vertex buffer + > reusable pool" particle technique outlined in the first post on this > thread WORKS GREAT. > > Is there any interest in my working this into away3d? I don't want to > duplicate anyone's efforts and find away3d to be such a moving target > right now it might break in the future so I'm hesitant. Let me know > if you think I should dive in. > > Anyways, in explanation, apart from doing all sim on the GPU, the > other optimizaton technique used here is I have also created a > "particle pool" so that particles are reused if inactive - this avoids > any GC issues: we don't "spawn" new particles each time there is a new > explosion, we just reuse old ones and only create new ones if there > aren't any inactive ones available. This means that the FPS hiccups > the very first few seconds as new particles are created but if you > hold down the spacebar for 2-3 seconds it stays near 60fps. > > For now, to help you out, since I may never bother implementing it > inside the dependency-rich away3d, here is the AGAL and scene setup > for the technique outlined above (two vertex buffers, one is the start > pos and one is the end pos, precalculated, for each vertex). None of > the animation is done in AS3 apart from calculating two constants that > go from 0..1 over time. It is all done in AGAL, and particles are > "batched" in chunks - I'm using 336 polies per drawtriangles call but > this could be any number. They key here is to NOT render each > particle separately. > > With some more work I am confident that 100,000+ particles is fully > achieveable at 60fps with room to spare for all your other scene > models since we aren't using the CPU for any of the heavy lifting. > > Enjoy! > > trace("Compiling the TWO FRAME particle shader..."); > vertexShader.assemble > ( > Context3DProgramType.VERTEX, > // scale the starting position > "mul vt0, va0, vc4.xxxx\n" + > // scale the ending position > "mul vt1, va2, vc4.yyyy\n" + > // interpolate the two positions > "add vt2, vt0, vt1\n" + > // 4x4 matrix multiply to get camera angle > "m44 op, vt2, vc0\n" + > // tell fragment shader about UV > "mov v1, va1" > ); > > // textured using UV coordinates > fragmentShader.assemble > ( > Context3DProgramType.FRAGMENT, > // grab the texture color from texture 0 > // and uv coordinates from varying register 1 > // and store the interpolated value in ft0 > "tex ft0, v1, fs0 <2d,linear,repeat,miplinear>\n" + > // multiply by "fade" color register (fc0) > "mul ft0, ft0, fc0\n" + > // move this value to the output color > "mov oc, ft0\n" > ); > > // RENDER LOOP: > // notes: > // age_scale is a Vector.<Number> that goes from [1,0,1,1] to > [0,1,1,1] > // rgba_scale is a Vector.<Number> that goes from [1,1,1,1] to > [0,0,0,0] > // these are calculated each frame using sin and elapsed time > // what the vertex shader above does is > // - multiply the vertex position of frame one by age_scale[0] > // - multiply the vertex position of frame two by age_scale[1] > // - and add them together for the interpolated position > > // Set the vertex program register vc0 to our model view projection > matrix > context.setProgramConstantsFromMatrix( > Context3DProgramType.VERTEX, 0, matrix, true); > > // Set the vertex program register vc4 to our time scale from (0..1) > // used to interpolate vertex positions over time > context.setProgramConstantsFromVector( > Context3DProgramType.VERTEX, 4, age_scale); > > // Set the fragment program register fc0 to our time scale from (0..1) > // used to interpolate colors and transparency over time > context.setProgramConstantsFromVector( > Context3DProgramType.FRAGMENT, 0, rgba_scale); > > // Set the AGAL program > context.setProgram(shader); > > // Set the fragment program register ts0 to a texture > context.setTextureAt(0,texture); > > // starting position (va0) > context.setVertexBufferAt(0, mesh.positionsBuffer, > 0, Context3DVertexBufferFormat.FLOAT_3); > // tex coords (va1) > context.setVertexBufferAt(1, mesh.uvBuffer, > 0, Context3DVertexBufferFormat.FLOAT_2); > // final position (va2) > context.setVertexBufferAt(2, mesh2.positionsBuffer, > 0, Context3DVertexBufferFormat.FLOAT_3); > > context.setBlendFactors(blend_src, blend_dst); > context.setDepthTest(depth_test,depth_test_mode); > context.setCulling(culling_mode); > > // render it > context.drawTriangles(mesh.indexBuffer, > 0, mesh.indexBufferCount); > -- ___________________ Actionscript 3.0 Flash 3D Graphics Engine HTTP://AWAY3D.COM
