LWJGL Sprite Overlay Problem (halbtransparent)

[Friedhelm]

Hallo,

Ich komme nicht weiter. Ich bin soweit, dass ich 2 Sprites über den Bildschirm bewege, doch wenn diese sich überlappen, dann wird das Raumschiff halbtransparent.

Jedoch möchte ich gerne das das Raumschiff kurzzeitig hinter dem Trümmer verschwindet.


Meine GLinit()

GL11.glEnable(GL11.GL_TEXTURE_2D); // Enable Texture Mapping
GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Black Background
GL11.glClearDepth(1.0f); // Depth Buffer Setup
GL11.glDisable(GL11.GL_DEPTH_TEST); // Enables Depth Testing
GL11.glDepthMask(false);
GL11.glMatrixMode(GL11.GL_PROJECTION); // Select The Projection Matrix GL11.glLoadIdentity(); // Reset The Projection Matrix
GL11.glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glEnable(GL11.GL_BLEND);
GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE);



Meine GLSpriteDraw:

GL11.glPushMatrix();
GL11.glLoadIdentity();
GL11.glBindTexture(GL11.GL_TEXTURE_2D, textures[0].getTextureId() );
GL11.glTranslatef(position.x,position.y,Screen.DEFAULT_Z);
GL11.glRotatef(this.rotation,0f,0f,1f);
GL11.glColor3f(1,1,1);

GL11.glBegin(GL11.GL_QUADS);
{
GL11.glTexCoord2f(textureRight,textureUp); //Upper right
GL11.glVertex2f(width, -height);
GL11.glTexCoord2f(textureLeft,textureUp); //Upper left
GL11.glVertex2f(-width, -height);
GL11.glTexCoord2f(textureLeft,textureDown); //Lower left
GL11.glVertex2f(-width,height);
GL11.glTexCoord2f(textureRight,textureDown); // Lower right
GL11.glVertex2f(width,height);
}
GL11.glEnd();
GL11.glPopMatrix();



Kann jemand einen Fehler entdecken?

Ich habe irgendwas gehört, dass die PNG-Image Lademethode unter MacOS Java 1.6 buggy sein soll. könnte es vielleicht daran liegen?

 

[Friedhelm]

Ich habe durch Zufall das Problem selbst gelöst. Beim stöbern durch zahlreiche Foren, habe ich einfach mal ein paar Sachen probiert. Das was funktioniert hat ist das:


GLinit:

GL11.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // Black Background
GL11.glClearDepth(1.0f); // Depth Buffer Setup
GL11.glDisable(GL11.GL_DEPTH_TEST); // Enables Depth Testing
GL11.glDepthMask(false);
GL11.glMatrixMode(GL11.GL_PROJECTION); // Select The Projection Matrix
GL11.glLoadIdentity(); // Reset The Projection Matrix
GL11.glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1);
GL11.glMatrixMode(GL11.GL_MODELVIEW);




RenderLoop:

// clear screen
GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glLoadIdentity();



GLSpriteDraw:

GL11.glPushMatrix();

GL11.glEnable(GL11.GL_BLEND);
GL11.glBlendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);
GL11.glEnable(GL11.GL_ALPHA_TEST);
GL11.glAlphaFunc(GL11.GL_GREATER, 0);

GL11.glEnable(GL11.GL_TEXTURE_2D);

textures[0].bind();

GL11.glTranslatef(position.x,position.y,position.z);
GL11.glRotatef(this.rotation,0f,0f,1f);
GL11.glColor3f(1,1,1);

GL11.glBegin(GL11.GL_QUADS);
{
GL11.glTexCoord2f(textureRight,textureUp);
GL11.glVertex2f(width, -height);
GL11.glTexCoord2f(textureLeft,textureUp);
GL11.glVertex2f(-width, -height);
GL11.glTexCoord2f(textureLeft,textureDown);
GL11.glVertex2f(-width,height);
GL11.glTexCoord2f(textureRight,textureDown);
GL11.glVertex2f(width,height);
}
GL11.glEnd();

GL11.glDisable(GL11.GL_TEXTURE_2D);
GL11.glTexEnvi(GL11.GL_TEXTURE_ENV, GL11.GL_TEXTURE_ENV_MODE, GL11.GL_MODULATE);

GL11.glDisable(GL11.GL_BLEND);


GL11.glPopMatrix();


An den PNG's hat's somit nicht gelegen 🙂 (war schon verzweifelt)

 

[jenetic]

Thank you so much for this solution!! 🙂

I've been looking for a way to draw translucent bitmaps that have a transparent background in ortho-mode for a long time now!

🙂

Thank you so much for mentioning the proper function

    GL11.glEnable(GL11.GL_ALPHA_TEST);
    GL11.glAlphaFunc(GL11.GL_GREATER, 0);

I finally solved my function to draw any bitmap with a different alpha value:

        @Override
        public void drawOrthoBitmapBytes( LibGLImage glImage, int x, int y, int alpha ) // TODO alter to float!
        {
            //prepare rendering 2D
            setOrthoOn();

            //be sure to disable texturing - bytes will not be drawn otherwise
            GL11.glDisable( GL11.GL_TEXTURE_2D );

            //blending allows transparent pixels
            GL11.glEnable(  GL11.GL_BLEND );

            //get alpha as float
            float alphaF = (float)alpha / 255;

            //disable full alpha pixels - this is the solution we have been looking for a long time :)
            GL11.glEnable( GL11.GL_ALPHA_TEST );
            GL11.glAlphaFunc( GL11.GL_GREATER, 0 );

            //blend images translucent [ why can we mix GL 1.4 and GL 1.1 here and it works ?? ]
            GL11.glBlendFunc(   GL11.GL_CONSTANT_ALPHA, GL11.GL_ONE_MINUS_CONSTANT_ALPHA );
            GL14.glBlendColor( 1.0f, 1.0f, 1.0f, alphaF );

            //set and draw pixels - this is a workaround to allow negative coordinates
            GL11.glRasterPos2f( 0, 0 );
            GL11.glBitmap( 0, 0, 0, 0, x, y, glImage.bytes );  //
            GL11.glDrawPixels( glImage.width, glImage.height, getSrcPixelFormat( glImage.srcPixelFormat ), GL11.GL_UNSIGNED_BYTE, glImage.bytes );

            //disable blending
            GL11.glDisable( GL11.GL_BLEND );

            //restore previous perspective and model views
            setOrthoOff();
        }

Thanks again! 🙂

jenetic.bytemare

'real coders may cast to void but never die.'