♪~ It works.
The terrifying pigs are rendered with glDisable(GL11.GL_LIGHTING) and OpenGlHelper.setLightmapTextureCoords(OpenGlHelper.lightmapTexUnit, 240f, 240f). Yep, Minecraft also use lightmap to control brightness. The door is drew with setBrightness(15728880).
BTW, resetting the lightmap without disabling OpenGL light source will make Entities more soft.
Codes of Standardized Entity Render
GL11.glPushMatrix();
GL11.glDisable(GL11.GL_LIGHTING);
OpenGlHelper.setLightmapTextureCoords(OpenGlHelper.lightmapTexUnit, 240f, 240f);
...render...
GL11.glEnable(GL11.GL_LIGHTING);
GL11.glPopMatrix();
Codes of Tessellator Drawer
tessellator.setBrightness(15728880);
If you are curious about why I chose 15728880...
15728880 = 15 << 20 | 15 << 4
The first 15 is lighting of environment, and the second 15 is lighting of itself.
So, I guess that 15728880 is potential the brightest lighting in game...