CODEWITHSUNDEEP
opengl3d
Yuriy Leonov
Yuriy Leonov

Reputation: 504

OpenGL. What should take glEnable for make texute transparent and with hard pixel edges

Given:

I have x.png image which contains 4 pixels(let it be square) with collors: red, green, blue and 4-th is transparent.
enter image description here

Required:

I need to find combination of arguments glEnable() and/or glBlendFunc() which will give following effect:
1) Texture applies without "smoothing", just sharp pixel edges.
2) Transtarent pixel is transparent.

Current code base:

def set_3d(self):
    ...
    glEnable(GL_BLEND)
    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
    glTranslatef(x, y, z)  # for getting scale image
   ...
   # + here is adding background rect(blue) and rect with 4 pixels

def add_alpha_rect(self, batch):
    ... # getting textures, etc.
    batch.add(
            4, GL_QUADS,
            texture_group,
            ('v3f', (x, y, z,
                     x_, y, z,
                     x_, y_, z
                     x, y_, z)),
            ('t3f', (0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0, 1.0, 0.0)))

Current result:

enter image description here

Expected result:

enter image description here

Question:

How I can achive that result?
Is it possible?

Upvotes: 0

Views: 101

Answers (1)

Rabbid76
Rabbid76

Reputation: 211126

You have to set the texture magnification function. This filter is used when the texture is magnified.
The magnification function can be set by glTexParameteri. Possible values are GL_LINEAR and GL_NEAREST. The initial value is GL_LINEAR.

Apply the magnification parameter GL_NEAREST to the bound texture object, to solve your issue:

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)

Note while the parameter GL_LINEAR would cause that the weighted average of the 4 texture elements that are closest to the specified texture coordinates are returned, GL_NEAREST causes that the value of the texture element that is nearest is returned, when the texture is looked up.

Upvotes: 3

Related Questions