Question

My texture itself has a transparent background, and I would like to render it as-is.

glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);

glPushMatrix();

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

glTranslatef(x, y, 0.0f);
glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
glVertexPointer(2, GL_FLOAT, 0, undoVertCoord);
glTexCoordPointer(2, GL_FLOAT, 0, undoTexCoord);
glBindTexture(GL_TEXTURE_2D, texUndo);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);

The problem is with glColor4f. That function seems to overwrite the transparency of the texture, making parts opaque when it should be transparent. But if I feed glColor4f with alpha value of 0, the whole texture becomes transparent.

SO, can you render a texture that ignores glColor4f, rendering the texture as-is? Or in a way that doesn’t affect the alpha values?

Answer 1

What is your GL_TEXTURE_ENV_MODE set to? Try setting it to GL_REPLACE.

glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);