Java OpenGL混合图像颜色

应绘制图像1作为基础图像。图2应该画在图1的上方。如果图像2是非透明的,它应该替换图像1的内容(不是混合,而是覆盖其中的内容)。只要图像2是透明的,图像1就会显示出来。我试着用下面的代码来实现这一点,但显然我在混合方面做得不正确。

            gl.glEnable(GL.GL_BLEND);
            if (iconTexture1 != null)
            {
                gl.glEnable(GL.GL_TEXTURE_2D);
                iconTexture1.bind();
                double red = (double) fillColor.getRed() / 255.0;
                double green = (double) fillColor.getGreen() / 255.0;
                double blue = (double) fillColor.getBlue() / 255.0;
                gl.glColor4d(red, green, blue, this.getOpacity());
                gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
                TextureCoords texCoords = iconTexture1.getImageTexCoords();
                gl.glScaled(width, height, 1d);
                dc.drawUnitQuad(texCoords);
            }
            if (iconTexture2 != null)
            {
                gl.glEnable(GL.GL_TEXTURE_2D);
                iconTexture2.bind();
                // image2 is all white, so color it here
                gl.glColor4d(1d, 0d, 0d, 1d);

                // TODO: What blend function should I be using here to allow image 2 to overwrite what is already there?

                TextureCoords texCoords = iconTexture2.getImageTexCoords();
                gl.glScaled(width, height, 1d);
                dc.drawUnitQuad(texCoords);
            }

杰夫