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particle effects billboarding issue[C++]


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#1 GeoKureli   Members   -  Reputation: 113

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Posted 25 August 2012 - 11:11 AM

I've included pictures of whats happening as well as my "particle" image. The issue is i have a bunch a billboards showing a particle, but the alpha doesn't seem to be working in some cases, but it works in some cases. for instance if i stack the particleThis is an assignment I have for class

[source lang="cpp"]// render the grid d3ddev->SetRenderState(D3DRS_ALPHABLENDENABLE, FALSE); render_grid();d3ddev->SetRenderState(D3DRS_ALPHABLENDENABLE, TRUE); // calculate elapsed time static DWORD starting_point = GetTickCount(), time; time = GetTickCount() - starting_point; starting_point = GetTickCount();addParticles(); // prepare particle for renderingNode<Particle> *particle = particles.first;D3DXMATRIX patMat;float y = 0;while (particle != NULL){ particle->value->run_particle(time / 1000.0f); //particle->value->position.y = y; if(particle->value->isDead()) particle->value->reset(); patMat = particle->value->set_particle(camx, camy, camz); d3ddev->SetTransform(D3DTS_WORLD, &patMat); particle->value->render_particle(); // --- NEXT particle = particle->next; y += .05;}d3ddev->EndScene();[/source]
"particles" is a linked list, addparticles adds some particles to the list until the cap is reached, and when particle die they get reset. when i draw X amount of the particles at the same position, they all draw, andit looks like a brighter version of the particle, however when i move them randomly they loook like the images below heres the particle class:
[source lang="cpp"]#include <d3dx9.h>float random(float max, bool negative = true){ if(negative) return cos(float(rand()))*max; /*else*/ return abs(cos(float(rand())))*max;}// the Particle classclass Particle{protected: D3DXVECTOR3 velocity; D3DXVECTOR3 acceleration; float radius; D3DXMATRIX matRotateX; D3DXMATRIX matRotateY;public: D3DXVECTOR3 position; Particle(); void reset(); void render_particle(); D3DXMATRIX set_particle(float camx, float camy, float camz); void run_particle(float seconds); bool isDead();};Particle :: Particle(){ reset(); }void Particle :: reset(){ position = D3DXVECTOR3(random(0.5f), 0.0, random(0.5f)); velocity = D3DXVECTOR3(random(0.5f), random(1.0f, false)+0.5f, random(0.5f)); acceleration = D3DXVECTOR3(0.0f, 0.0f, 0.0f); radius = random(0.5f, false)+0.5f;}bool Particle :: isDead(){ return radius <= 0.0f; }// this is the function that positions, rotates, scales and renders the particleD3DXMATRIX Particle::set_particle(float camx, float camy, float camz){ // Before setting the world transform, do the intense mathematics! // a. Calculate the Differences static float difx, dify, difz; difx = camx - position.x; dify = camy - position.y; difz = camz - position.z; // ooh, intense! // b. Calculate the Distances static float FlatDist, TotalDist; FlatDist = sqrt(difx * difx + difz * difz); TotalDist = sqrt(FlatDist * FlatDist + dify * dify); // c. Y Rotation D3DXMatrixIdentity(&matRotateY); matRotateY._11 = matRotateY._33 = difz / FlatDist; // cosY matRotateY._31 = difx / FlatDist; // sinY matRotateY._13 = -matRotateY._31; // -sinY // d. X Rotation D3DXMatrixIdentity(&matRotateX); matRotateX._22 = matRotateX._33 = FlatDist / TotalDist; // cosX matRotateX._32 = dify / TotalDist; // sinX matRotateX._23 = -matRotateX._32; // -sinX // e. Tranlation static D3DXMATRIX matTranslate; D3DXMatrixTranslation(&matTranslate, position.x, position.y, position.z); // f. Scaling static D3DXMATRIX matScale; D3DXMatrixIdentity(&matScale); matScale._11 = matScale._22 = matScale._33 = radius; return matScale * matRotateX * matRotateY * matTranslate;}// this function updates the particlevoid Particle::run_particle(float seconds){ velocity += acceleration * seconds; position += velocity * seconds; radius -= seconds; return;}[/source]

Attached Thumbnails

  • fire_1.png
  • fire_2.png
  • fire.png

Edited by GeoKureli, 25 August 2012 - 11:12 AM.


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#2 ryan20fun   Members   -  Reputation: 1277

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Posted 25 August 2012 - 12:32 PM

i think that has to do with the zbuffer and the blending state settings.
have a look at this article for the renderstate settings he uses for particles :)

here is the 'generic' settings
lpDevice->SetRenderState(D3DRENDERSTATE_ALPHABLENDENABLE, true);
lpDevice->SetRenderState(D3DRENDERSTATE_SRCBLEND, D3DBLEND_ONE);
lpDevice->SetRenderState(D3DRENDERSTATE_DESTBLEND, D3DBLEND_ONE);
lpDevice->SetRenderState(D3DRENDERSTATE_LIGHTING, false);
lpDevice->SetRenderState(D3DRENDERSTATE_ZWRITEENABLE, false);

Hope that helps.
Never say Never, Because Never comes too soon. - ryan20fun

Disclaimer: Each post of mine is intended as an attempt of helping and/or bringing some meaningfull insight to the topic at hand. Due to my nature, my good intentions will not always be plainly visible. I apologise in advance and assure you I mean no harm and do not intend to insult anyone.

#3 Alundra   Members   -  Reputation: 1128

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Posted 25 August 2012 - 12:32 PM

You need to sort each particle Back-To-Front to have a correct render.
You don't need to do that for additive blending because each component is added to have the final color.
Use the bubble sort which is good for particle.

#4 Juliean   GDNet+   -  Reputation: 3171

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Posted 25 August 2012 - 01:17 PM

If you don't want to sort your particles back-to-front, you can use alpha-testing to reduce this effect:

dev->SetRenderState(D3DRS_ALPHAREF, (DWORD)0x00000001);
dev->SetRenderState(D3DRS_ALPHATESTENABLE, TRUE);
dev->SetRenderState(D3DRS_ALPHAFUNC, D3DCMP_GREATEREQUAL);


This will skip completely transparent pixels from being written to the z-buffer.

#5 GeoKureli   Members   -  Reputation: 113

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Posted 25 August 2012 - 03:20 PM

Thanks guys, it works great, and your suggestions added a lot of flair to the image. the issue was with:
d3ddev->SetRenderState(D3DRS_ZWRITEENABLE, false);
and these really made it look great!
d3ddev->SetRenderState(D3DRS_SRCBLEND, D3DBLEND_ONE);
d3ddev->SetRenderState(D3DRS_DESTBLEND, D3DBLEND_ONE);

Attached Thumbnails

  • fire 3.png





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