C++

Forum

 
seethrough texture help

desoxena (28)
Does anyone know if it's possible to make parts of a bitmap texture seethrough? Like, if a specific part of the bitmap is colored with a certain color, it's seethrough when it's displayed.Here's what I use to load textures so far.


P.S. I only included what I thought was relevant to the question.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
 
Gluint texture[100];
int LoadGLTextures(int ID)     
{
        texture[ID] = SOIL_load_OGL_texture("game_textures/buy_screen/egg_fef.bmp", SOIL_LOAD_AUTO, SOIL_CREATE_NEW_ID, SOIL_FLAG_INVERT_Y);
	glBindTexture(GL_TEXTURE_2D, texture[ID]);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
	return true;                                       
}
void drawTexture(int id, float x, float y, float z, float scale)
{
	LoadGLTextures(id);
	glBindTexture(GL_TEXTURE_2D, texture[id]);
	glBegin(GL_QUADS);
	glTexCoord2f(0.0f, 0.0f); glVertex3f(-scale+x, -scale+y,  z);
	glTexCoord2f(1.0f, 0.0f); glVertex3f( scale+x, -scale+y,  z);
	glTexCoord2f(1.0f, 1.0f); glVertex3f( scale+x,  scale+y,  z);
	glTexCoord2f(0.0f, 1.0f); glVertex3f(-scale+x,  scale+y,  z);
	glEnd();
}

//......
//in the draw function
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();          
        glColor3d(light,light,light);
	drawTexture(48,  -.86,  1.44,   -2.9995, .64);
        //bluh bluh, other code

        glutSetWindow(1);
	resize(600,600);
	glutPostRedisplay();
	glutSwapBuffers(); //352, 234


So what do I need to change to make parts of the image seethrough? thanks!
ModShop (1149)
I'm not familiar with how to use SOIL, but so long as it provides a way of reading/writing pixel values in textures, this is an easy problem to solve. When a texture is loaded, read all of its pixels values, and if their equal to the color that specifies transparency, change the value to a transparent one.
desoxena (28)
Well, that's what I had in mind, but how would I do that..? How do I loop through each and every pixel in a texture?
ModShop (1149)
That depends on how you access image info (width/height) and pixel data using SOIL. I have never used SOIL, so I'm not sure how its done, try checking the docs for it.
Disch (13742)
The easiest way is to store the transparent color in the image itself.

Convert the .bmp to a .png and set the desired color to be transparent in the .png (you can do this with any halfway decent image conversion program, there are many free ones available. read: MS Paint doesn't count).

Any decent image loading library will preserve transparency/alpha information and apply it to the texture.
Topic archived. No new replies allowed.