Transparency blending
Author
I'm working on a particle system and I'm stuck on getting them blended the correct way. I have 2 ways of blending that i want to put in my engine:
1. transparency
2. additive
the way i'm doing my particles is by texture so i've been messing around with the glBlendFunc() and glTexEnvi() functions. Also, when I create my texture, i should be doing something like this, right?
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_lWidth, m_lHeight,
0, GL_RGBA, GL_FLOAT, ilGetData());
Note: i'm using OpenIL (DevIL) for loading textures.
To achieve the two effects i want for my particles, what combinations of glBlendFunc() and glTexEnvi() functions should i do?
Edit: forgot to mention the texture i'm using for my particles is just a white circle that has an alpha of 0.0f on the outside and as it gets closer to the middle it fades to an alpha of 1.0f
Regular: GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA
Additive: GL_SRC_ALPHA, GL_ONE (or maybe GL_DST_ALPHA)
Additive: GL_SRC_ALPHA, GL_ONE (or maybe GL_DST_ALPHA)
Quote:Original post by Boder
Regular: GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA
Additive: GL_SRC_ALPHA, GL_ONE (or maybe GL_DST_ALPHA)
yes this is parameters for glBlendFunc and be sure that you have turn the depth test.
Author
those aren't working... is there a certain glTexEnvi() i should pass? or maybe i'm using glTexImage2D() wrong?
The default texEnv should be fine, I believe it is GL_MODULATE.
Make sure to call glEnable( GL_BLEND ); to enable blending [smile] Hope this helps.
Make sure to call glEnable( GL_BLEND ); to enable blending [smile] Hope this helps.
Author
yes blending is enabled.
yea, the texture has an alpha channel and it's using GL_FLOAT for it's components and GL_RGBA
yea, the texture has an alpha channel and it's using GL_FLOAT for it's components and GL_RGBA
Quote:Original post by EvilKnuckles666If that's the data type that ilGetData returns the image as, yes you should be using that instead of GL_FLOAT.
do I need to change the format to GL_UNSIGNED_BYTE?
It looks like ilGetData does indeed return an array of unsigned bytes.
Author
ok... not even that is working.. so, here's my entire code for loading and rendering a texture.. what could be wrong?
bool cWTexture::Load(std::string Filename){ FILE *file = NULL; if (IsLoaded()) Shutdown(); if (Filename == "") return cWUtility::ErrorLog.Write("cWTexture::Load() no filename"); // Check if file exists file = fopen(Filename.c_str(), "r"); if (file == NULL) return cWUtility::ErrorLog.Write("cWTexture::Load() no file ", Filename); fclose(file); ilGenImages(1, &m_ILTexID); ilBindImage(m_ILTexID); if (ilLoadImage((const ILstring)Filename.c_str()) == IL_FALSE) return cWUtility::ErrorLog.Write("cWTexture::Load() ilLoadImage() failed"); if (ilConvertImage(IL_RGBA, IL_UNSIGNED_BYTE) == IL_FALSE) return cWUtility::ErrorLog.Write("cWTexture::Load() ilConvertImage() failed"); glGenTextures(1, &m_TexID); glBindTexture(GL_TEXTURE_2D, m_TexID); m_lWidth = ilGetInteger(IL_IMAGE_WIDTH); m_lHeight = ilGetInteger(IL_IMAGE_HEIGHT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_lWidth, m_lHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, ilGetData()); return true;}// then a pointer to this texture is set to the particle system.. then here's the renderbool cWEmitter::RenderParticles(){ if (m_bActive == true) { if (Update() == false) return false; float PosX, PosY, PosZ; float TexLeft, TexRight, TexTop, TexBottom; float FraWidth, FraHeight; sWParticle* Particle; cWUtility::sWPosition *Pos; TexLeft = m_FrameSrcRect.left * 1.0f / m_pEmitterDef->m_pTex->GetWidth(); TexRight = m_FrameSrcRect.right * 1.0f / m_pEmitterDef->m_pTex->GetWidth(); TexTop = m_FrameSrcRect.top * 1.0f / m_pEmitterDef->m_pTex->GetHeight(); TexBottom = m_FrameSrcRect.bottom * 1.0f / m_pEmitterDef->m_pTex->GetHeight(); for (unsigned long i=0 ; i<m_ParticleVList.GetNetItems() ; i++) { Particle = m_ParticleVList.GetItem((long)i); Pos = &Particle->m_Pos; FraWidth = ((m_FrameSrcRect.right - m_FrameSrcRect.left) * 0.5f) * Pos->ScaleX; FraHeight = ((m_FrameSrcRect.bottom - m_FrameSrcRect.top) * 0.5f) * Pos->ScaleY; PosX = Pos->X; PosY = Pos->Y; PosZ = Pos->Z; // Position particle glTranslatef(PosX, PosY, -PosZ); glRotatef(Pos->Radian * (180/W_PI), 0.0f, 0.0f, 1.0f); // Bind the texture glBindTexture(GL_TEXTURE_2D, m_pEmitterDef->m_pTex->GetTextureID()); // Draw particle glBegin(GL_QUADS); { // Set color //glMaterialfv(GL_FRONT, GL_DIFFUSE, Particle->m_Color); // Top-left glTexCoord2d(TexLeft, TexTop); glVertex3f(-FraWidth, FraHeight, 0.0f); // Bottom-left glTexCoord2d(TexLeft, TexBottom); glVertex3f(-FraWidth, -FraHeight, 0.0f); // Bottom-right glTexCoord2d(TexRight, TexBottom); glVertex3f(FraWidth, -FraHeight, 0.0f); // Top-right glTexCoord2d(TexRight, TexTop); glVertex3f(FraWidth, FraHeight, 0.0f); } glEnd(); } } else return false; return true;} This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
