I was trying to implement a particle system using PointSprites. Draw calls return D3D_OK but I don't see any particle on the screen. I'm not using Vertex Buffer for the particles, but I use two vectors of vertices and I call the DrawPrimitiveUP function. This is my code:


            pD3DD -> SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE);
            pD3DD -> SetRenderState(D3DRS_SRCBLEND, D3DBLEND_SRCALPHA);
            pD3DD -> SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ONE);

            pD3DD -> SetRenderState(D3DRS_ZWRITEENABLE, FALSE);
            pD3DD -> SetRenderState(D3DRS_ZENABLE, FALSE);

            pD3DD -> SetRenderState(D3DRS_LIGHTING, FALSE);

            pD3DD -> SetFVF(FVF_PNTVERTEX);
            pD3DD -> SetTexture(0, pTex[TEX_POINT]);

            pD3DD -> SetRenderState(D3DRS_POINTSPRITEENABLE, TRUE);
            pD3DD -> SetRenderState(D3DRS_POINTSCALEENABLE, TRUE);

            pD3DD -> SetRenderState(D3DRS_POINTSCALE_A, 0.0f);
            pD3DD -> SetRenderState(D3DRS_POINTSCALE_B, 0.0f);
            pD3DD -> SetRenderState(D3DRS_POINTSCALE_C, 1.0f);

            pD3DD -> SetRenderState(D3DRS_POINTSIZE, 20.0f);
            pD3DD -> SetRenderState(D3DRS_POINTSIZE_MIN, 3.0f);
            pD3DD -> SetRenderState(D3DRS_POINTSIZE_MAX, 50.0f);

            pD3DD -> SetTransform(D3DTS_WORLD, &mWorld);

            pD3DD -> DrawPrimitiveUP(D3DPT_POINTLIST, pntPlanets.size(), (PVOID)pntPlanets.data(), sizeof(PNTVERTEX));

            pD3DD -> SetRenderState(D3DRS_POINTSIZE, 40.0f);
            pD3DD -> SetRenderState(D3DRS_POINTSIZE_MIN, 9.0f);
            pD3DD -> SetRenderState(D3DRS_POINTSIZE_MAX, 70.0f);

            pD3DD -> DrawPrimitiveUP(D3DPT_POINTLIST, pntStars.size(), (PVOID)pntStars.data(), sizeof(PNTVERTEX));

            pD3DD -> SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE);

            pD3DD -> SetRenderState(D3DRS_ZWRITEENABLE, TRUE);
            pD3DD -> SetRenderState(D3DRS_POINTSPRITEENABLE, FALSE);
            pD3DD -> SetRenderState(D3DRS_POINTSCALEENABLE, FALSE);

CreatePntVertices() is a function that set the position of objects and their color into two vectors of PNTVERTEX (pntStars and pntPlanets). pTex is an array of textures. mWorld is a D3DXMATRIX. pD3DD is the Device. FVF_PNTVERTEX is set as (D3DFVF_XYZ | D3DFVF_DIFFUSE). I really don't know why it doesn't work, I tried everything to make it work. Maybe, should I use a dynamic vertex buffer instead?

  • \$\begingroup\$ Have you confirmed your hardware actually supports point-sprites? D3DCAPS9.MaxPointSize has to be something other than 1.0 or 0.0. See MSDN. \$\endgroup\$ Feb 16 '15 at 0:50
  • \$\begingroup\$ @ChuckWalbourn D3DCAPS9.MaxPointSize returned 8192... \$\endgroup\$
    – Ale
    Feb 16 '15 at 17:00
  • \$\begingroup\$ I compiled another program which used point-sprites, and it worked... so the problem shouldn't be the hardware, but something in the code which I may have forgotten. I'm not able to find out the problem. Could someone tell me which other parameters I have to set? Also I tried to use dynamic VB but the result is the same. I have to add that I draw other things (like spheres or quads) and I don't know if it changes anything if I put this code at the end or at the beginning. \$\endgroup\$
    – Ale
    Feb 17 '15 at 16:14

I found out the source of the problem. After days and days, I understood (at last) that with SetRenderState (in DirectX9), floats have to be converted into DWORDs in this way:


where f is the floating point. I already used this method for fog, but I forgot it and it took me other weeks to learn it again. I hope this answer will help other guys with the same problem!

  • 1
    \$\begingroup\$ I'm amazed you were able to compile your program, passing a float to a function that takes a DWORD. You didn't even get a warning for that? Additionally, the documentation clearly states that you must binary convert the float to a DWORD to pass the float value to SetRenderState(). Always remember to read the docs, and read your compiler output. Aiming for 0 warnings can be a good practice. \$\endgroup\$ Feb 25 '15 at 7:30
  • \$\begingroup\$ @PandaPajama No, I didn't receive any error! That was the real problem. If I got a message, probably I wouldn't lose so much time searching for the bug. I don't know why, but the program were compiled without warnings. I read the documentation, but I didn't find the statement (although I may have been more careful reading it). I found the problem comparing my program with another program which uses PointSprites. In fact, the difficulty was to find what was going wrong - It's relatively easy to fix a bug if you know what caused it ;) \$\endgroup\$
    – Ale
    Feb 25 '15 at 17:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.