Skybox textures do not display correctly

问题

I have a problem with skybox textures. If you twist the camera, it creates a feeling that one texture overlays another, as in the screenshot:

Skybox show code:

private void drawSkybox(int texId){

    glColor4f(1,1,1,1);
    glDepthMask(false);
    glEnable(GL_TEXTURE_CUBE_MAP);
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_CUBE_MAP, texId);
    glBindVertexArray(vao[0]);
    glBindBuffer (GL_ARRAY_BUFFER, vbo[0]);
    glDrawArrays(GL_TRIANGLES, 0, 36);
    glBindVertexArray(0);
    glBindBuffer (GL_ARRAY_BUFFER, 0);
    glDepthMask(true);
    glDisable(GL_TEXTURE_CUBE_MAP);
}

My opengl paramters:

glEnable(GL_ALPHA_TEST);
glEnable(GL_DEPTH_TEST);
glEnable(GL_COLOR_MATERIAL);
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glEnable(GL_NORMALIZE);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glShadeModel(GL_SMOOTH);
glColorMask (true, true, true, true);
glHint(GL_LINE_SMOOTH_HINT, GL_DONT_CARE);

And my call drawSkybox:

glViewport(0, 0, WIDTH, HEIGHT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-max, max, -1, 1, 10, -10);
glRotated(cameraX, 1f, 0f, 0);
glRotated(cameraY, 0f, 1f, 0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
drawSkybox(texId);

How i can fix the problem?

I understand that the problem is glDepthMask(false); but how can it be replaced?

If I just remove glDepthMask(false); and replace it with an example with glDepthFunc(GL_LEQUAL); and glDepthFunc(GL_LESS); then the skybox will overlap all other objects and only it will be visible –

回答1:

Do not change the depth mask or the depth test when you draw the skybox. Keep the depth test function GL_LESS.

private void drawSkybox(int texId){

    glColor4f(1,1,1,1);
    // glDepthMask(false); <---- DELETE

    // [...]
}

But clear the depth buffer again, after drawing the skybox. Draw the skybox first, then the skybox covers the entire screen. Then clear the depth buffer, thus all objects which are draw after, will cover the skybox:

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

// [...]

drawSkybox(texId);
glClear(GL_DEPTH_BUFFER_BIT);

// render other objects
// [...]

来源：https://stackoverflow.com/questions/61181470/skybox-textures-do-not-display-correctly

标签

java

opengl

textures

lwjgl

skybox