Multitexturing with Tiled Textures

I working on a small terrain demo which uses tiled textures. Currently I'm doing 3 passes over the terrain using blending. A base texture, then two textures blended on top. Since the textures are tiled the alpha values for the blending are not part of the texture or an alphamap, but kept at each vertex. That is the alpha information for each texture is stored at each individual vertex. As I mentioned at the moment I doing three passes over the terrain to texture. In addition to this I'm doing one pass for the water - I've also now added stencil relfections, so I'm up to 8 passes per frame. My question is, is there a way to blend the textures as described (an alpha value stored at each vertex) using multitexturing. My current terrain rendering step (with its 3 passes):

	glEnable(GL_BLEND);

	glBindTexture(GL_TEXTURE_2D, texture[texFilter]);
	glBlendFunc(GL_ONE, GL_ZERO);
	glBegin(GL_QUADS);
	z= TERR_DEPTH-1;
	while (z-- > 0)
	{
		x= TERR_WIDTH-1;
		while (x-- > 0)
		{
			glColor4f(1.0f, 1.0f , 1.0f, 0.0f);

			glTexCoord2f(0.0f, 0.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x][z]));
			glVertex3f(x, pTB->h.s[x][z], z);

			glTexCoord2f(0.0f, 1.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x][z+1]));
			glVertex3f(x, pTB->h.s[x][z+1], z+1);

			glTexCoord2f(1.0f, 1.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x+1][z+1]));
			glVertex3f(x+1, pTB->h.s[x+1][z+1], z+1);

			glTexCoord2f(1.0f, 0.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x+1][z]));
			glVertex3f(x+1, pTB->h.s[x+1][z], z);
			
				
		}
	}
glEnd();

	glEnable(GL_ALPHA_TEST);

	glDepthFunc(GL_LEQUAL);

	glBindTexture(GL_TEXTURE_2D, texture[rockTex]);
	glBlendFunc(GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA);
	
	glBegin(GL_QUADS);

	z= TERR_DEPTH-1;
	while (z-- > 0)
	{
		x= TERR_WIDTH-1;
		while (x-- > 0)
		{
			
			glColor4f(1.0f, 1.0f , 1.0f, rockMap[x][z]);
			glTexCoord2f(0.0f, 0.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x][z]));
			glVertex3f(x, pTB->h.s[x][z], z);

			glColor4f(1.0f, 1.0f , 1.0f, rockMap[x][z+1]);
			glTexCoord2f(0.0f, 1.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x][z+1]));
			glVertex3f(x, pTB->h.s[x][z+1], z+1);

			glColor4f(1.0f, 1.0f , 1.0f, rockMap[x+1][z+1]);
			glTexCoord2f(1.0f, 1.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x+1][z+1]));
			glVertex3f(x+1, pTB->h.s[x+1][z+1], z+1);

			glColor4f(1.0f, 1.0f , 1.0f, rockMap[x+1][z]);
			glTexCoord2f(1.0f, 0.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x+1][z]));
			glVertex3f(x+1, pTB->h.s[x+1][z], z);
		}
	}
	glEnd();


	glBindTexture(GL_TEXTURE_2D, texture[sandTex]);
	glBlendFunc(GL_ONE_MINUS_SRC_ALPHA, GL_SRC_ALPHA);
	
	glBegin(GL_QUADS);

	z= TERR_DEPTH-1;
	while (z-- > 0)
	{
		x= TERR_WIDTH-1;
		while (x-- > 0)
		{
			
			glColor4f(1.0f, 1.0f , 1.0f, sandMap[x][z]);
			glTexCoord2f(0.0f, 0.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x][z]));
			glVertex3f(x, pTB->h.s[x][z], z);

			glColor4f(1.0f, 1.0f , 1.0f, sandMap[x][z+1]);
			glTexCoord2f(0.0f, 1.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x][z+1]));
			glVertex3f(x, pTB->h.s[x][z+1], z+1);

			glColor4f(1.0f, 1.0f , 1.0f, sandMap[x+1][z+1]);
			glTexCoord2f(1.0f, 1.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x+1][z+1]));
			glVertex3f(x+1, pTB->h.s[x+1][z+1], z+1);

			glColor4f(1.0f, 1.0f , 1.0f, sandMap[x+1][z]);
			glTexCoord2f(1.0f, 0.0f);
			glNormal3fv((GLfloat*)&(pTB->n[x+1][z]));
			glVertex3f(x+1, pTB->h.s[x+1][z], z);
		}
	}
	glEnd(); 

[edited by - The Bag on April 25, 2004 6:10:28 PM]