transition between two texture opengl + delphi

[jplev]

Hi
i work on an myst-like game engine with opengl and delphi 7
i try to do transition between two texture but i dont know how in OpenGl
anyone can help me?
i want to blend two texture into one.

Thanks
JP

[Nitrogen]

The simplest way is like this:



(initalisation)
Set Orthographic Projection mode.
Load Texture into Tex1
Load Texture into Tex2

glDisable(GL_LIGHTING);
glEnable(GL_TEXTURE_2D);
glDisable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);


(drawing)

Fade := (a number ranging from 0.0 to 1.0 where 0 means Tex1 is visible, 1 = Tex2 visible.)

glBindTexture2D(GL_TEXTURE_2D, Tex1);
glColor4f(1,1,1, Fade);

glBegin(GL_QUADS);
glTexCoord2f(0, 1); glVertex2f(0,0);
glTexCoord2f(1, 1); glVertex2f(Width,0);
glTexCoord2f(1, 0); glVertex2f(Width,Height);
glTexCoord2f(0, 0); glVertex2f(0,Height);
glEnd;

glBindTexture2D(GL_TEXTURE_2D, Tex2);
glColor4f(1,1,1, 1-Fade);

glBegin(GL_QUADS);
glTexCoord2f(0, 1); glVertex2f(0,0);
glTexCoord2f(1, 1); glVertex2f(Width,0);
glTexCoord2f(1, 0); glVertex2f(Width,Height);
glTexCoord2f(0, 0); glVertex2f(0,Height);
glEnd;