Mixing 2 blending functions for 1 scene 2d

OpenGL OpenGL: Basic Coding
1

Is it possible to use different blending functions for different parts of te scene ?
Say i want to render sprites in a 2D ame & i use

glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA)
glBegin(GL_QUADS);

//Render sprites
glEnd();

then for light mapping to create lights in te 2D scene i do(immediately after above)

glBlendFunc(GL_SRC_ALPHA,GL_ONE);
glBegin(GL_QUADS);
//put light textures on pixels already in te screen
glEnd();

but i have noticed that only the last glBlendFunc(GL_SRC_ALPHA,GL_ONE) applies to whole scene!

the problem is this :-

Mixing 2 blending functions for 1 scene 2d lighting
I first draw the terrain & castle wit the appropriate regions transparent & blending enabled to get irregular outline.i use
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

Then i use a light texture(visible clearly in right pic) & draw it with
glBlendFunc(GL_SRC_ALPHA,GL_ONE);
& i get the effect i want from the light but the castle has flared up too
With just
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPhHA);
i get a solid castle but lose the lighting effect!(right side)

I tried to use GL_LUMINANCE & stored the light values like this(for a uniform square shaped light…not the 1 above)

unsigned int img[32][32];
for (i = 0; i < 32; i++)
	for (int j = 0; j < 32; j++){
		img[i][j]=   255; 
 
glTexImage2D(GL_TEXTURE_2D, 0, 1, 32,32, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, TextureImage[2]->pixels);

But the program crashes

So what is the best way i can implement lightin here in my 2D game wit ortho views

2

You know, it should work, but you can try something like this.

glBlendFunc(GL_SRC_ALPHA,GL_ONE_MINUS_SRC_ALPHA);
glEnable(GL_BLEND);
glBegin(GL_QUADS);

//Render sprites
glEnd();
glDisable(GL_BLEND);

glBlendFunc(GL_ONE,GL_ONE);
glEnable(GL_BLEND);
glBegin(GL_QUADS);
//put light textures on pixels already in te screen
glEnd();
glDisable(GL_BLEND);

I don’t know if it will work, but it doesn’t hurt to try.

3

Nope now i et tis

i used

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
	glBindTexture(GL_TEXTURE_2D, textures[2]);//castle
	
	glEnable(GL_BLEND);
	glBegin(GL_QUADS);
	  glTexCoord2f(0.0f, 0.0f);glVertex2i(100,100);	 
	  glTexCoord2f(1, 0.0f);glVertex2i(400, 100); 
	  glTexCoord2f(1, 1); glVertex2i(400, 400);  
	  glTexCoord2f(0.0f, 1);  glVertex2i(100, 400); 
	glEnd();
	glDisable(GL_BLEND);
	
	glBlendFunc(GL_SRC_ALPHA,GL_ONE);
	glBindTexture(GL_TEXTURE_2D, textures[1]);//lights


	glEnable(GL_BLEND);
	glBegin(GL_QUADS);
	  glTexCoord2f(0.0f, 0.0f);glVertex2i(100,100);	 
	  glTexCoord2f(1, 0.0f);glVertex2i(150, 100); 
	  glTexCoord2f(1, 1); glVertex2i(150, 150);  
	  glTexCoord2f(0.0f, 1);  glVertex2i(100, 150); 
	glEnd();
	glDisable(GL_BLEND);
	
	 
	SDL_GL_SwapBuffers( );

i set up view like tis

//Resize the scene
GLvoid ReSizeGLScene(GLsizei width, GLsizei height)		// Resize And Initialize The GL Window
{

	if (height==0)										// Prevent A Divide By Zero By
	{
		height=1;										// Making Height Equal One
	}

	glViewport(0, 0, width, height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	// Calculate The Aspect Ratio Of The Window
	gluOrtho2D(0, width, height, 0);
	//glOrtho(0,640,480,0,-1,1);


	glMatrixMode(GL_MODELVIEW);							// Select The Modelview Matrix
	glLoadIdentity();									// Reset The Modelview Matrix
	
	// Nice perspective correction
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); 
	// Allow 2D textures
	
	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);					// Set The Blending Function For Translucency
	
	glEnable(GL_TEXTURE_2D);
		    
}