How to apply shader to a openGL render object 1.12.2

Hey guys, i'm currently developping a mod with forge 1.12.2 2860 and i'm using optifine and gradle 4.9. The thing is i'm trying to figure out how to show the player's body in first person. So far everything's going well since i've try to use a shader. The player's body started to blink dark when using a shader. I've try a lot of shader like chocapic, zeus etc etc but still the same issue. So my question is : How should i apply the current shader to the body ? At the same time i'm also drawing a HUD so maybe it could be the problem?

Here is the issue : 

And here is the code where i'm trying to display the body : 

 

private static void renderFirstPersonBody(EntityPlayerSP player, float partialTicks) {
        Minecraft mc = Minecraft.getMinecraft();

        GlStateManager.pushMatrix();
        GlStateManager.pushAttrib();

        try {
            // Préparation OpenGL
            GlStateManager.enableDepth();
            GlStateManager.depthMask(true);
            GlStateManager.enableAlpha();
            GlStateManager.alphaFunc(GL11.GL_GREATER, 0.1F);
            GlStateManager.enableBlend();
            GlStateManager.blendFunc(GL11.GL_SRC_ALPHA, GL11.GL_ONE_MINUS_SRC_ALPHA);

            // Éclairage correct pour shaders
            GlStateManager.enableLighting();
            RenderHelper.enableStandardItemLighting();
            GlStateManager.enableRescaleNormal();

            // Active la lightmap pour les shaders
            mc.entityRenderer.enableLightmap();

            // Position de rendu interpolée
            double px = player.lastTickPosX + (player.posX - player.lastTickPosX) * partialTicks;
            double py = player.lastTickPosY + (player.posY - player.lastTickPosY) * partialTicks;
            double pz = player.lastTickPosZ + (player.posZ - player.lastTickPosZ) * partialTicks;

            GlStateManager.translate(
                    px - mc.getRenderManager().viewerPosX,
                    py - mc.getRenderManager().viewerPosY,
                    pz - mc.getRenderManager().viewerPosZ
            );

            // Rendu du joueur sans la tête
            Render<?> render = mc.getRenderManager().getEntityRenderObject(player);
            if (render instanceof RenderPlayer) {
                RenderPlayer renderPlayer = (RenderPlayer) render;

                boolean oldHeadHidden = renderPlayer.getMainModel().bipedHead.isHidden;
                boolean oldHeadwearHidden = renderPlayer.getMainModel().bipedHeadwear.isHidden;

                renderPlayer.getMainModel().bipedHead.isHidden = true;
                renderPlayer.getMainModel().bipedHeadwear.isHidden = true;
                setArmorHeadVisibility(renderPlayer, false);

                renderPlayer.doRender(player, 0, 0, 0, player.rotationYaw, partialTicks);

                renderPlayer.getMainModel().bipedHead.isHidden = oldHeadHidden;
                renderPlayer.getMainModel().bipedHeadwear.isHidden = oldHeadwearHidden;
                setArmorHeadVisibility(renderPlayer, !oldHeadwearHidden);
            }

            // Nettoyage post rendu
            mc.entityRenderer.disableLightmap();
            GlStateManager.disableRescaleNormal();

        } catch (Exception e) {
            // silent fail
        } finally {
            GlStateManager.popAttrib();
            GlStateManager.popMatrix();
        }
    }

Ty for your help.