[1.17] Render texture on a specified pattern

I'm trying to create a custom renderer for my entity and in order to do so I need to draw a sprite that has a lava texture and also a mask indicating which pixels to apply texture colors to. I've made quite a few attempts to implement this sort of thing, but all my scripts have either rendered nothing or just rendered a texture. Below is the code for my latest attempt. This code renders just a texture (instead of lava, I temporarily use a custom image). I would be grateful for any hints on how to fix it.

So this is my test script:

@Override
    public void render(EntityEruptionSource entity, float entityYaw, float partialTicks, PoseStack pose, MultiBufferSource buffer, int packedLight)
    {
        pose.pushPose();
        Vector3f vertexRotAxis = new Vector3f(0, 1, 0);
        
        GL11.glEnable(GL11.GL_STENCIL_TEST);
        GL11.glClear(GL11.GL_STENCIL_BUFFER_BIT);
        GL11.glStencilMask(0xFF);
        GL11.glStencilFunc(GL11.GL_ALWAYS, 1, 0xFF);
        GL11.glStencilOp(GL11.GL_KEEP, GL11.GL_KEEP, GL11.GL_REPLACE);
        VertexConsumer builder = buffer.getBuffer(RenderType.entityCutout(MainClass.RLof("textures/entities/eruption_source_mask.png")));
        Vector3f vertexPos = new Vector3f(-0.5f, 0.2f, 0.5f);
        for(int i = 0; i < 4; i++)
        {
            builder.vertex(pose.last().pose(), -vertexPos.x(), vertexPos.y(), -vertexPos.z())
                    .color(255, 255, 255, 255)
                    .uv(0, 0)
                    .overlayCoords(OverlayTexture.NO_OVERLAY)
                    .uv2(packedLight)
                    .normal(0, 1, 0)
                    .endVertex();
            vertexPos.transform(new Quaternion(vertexRotAxis, 90, true));
        }

        GL11.glStencilMask(0x00);
        GL11.glStencilFunc(GL11.GL_NOTEQUAL, 0, 0xFF);
        vertexPos = new Vector3f(-0.5f, 0.2f, 0.5f);
        VertexConsumer builder1 = buffer.getBuffer(RenderType.entityCutout(MainClass.RLof("textures/entities/eruption_source_c.png")));
        for(int i = 0; i < 4; i++)
        {
            builder1.vertex(pose.last().pose(), -vertexPos.x(), vertexPos.y(), -vertexPos.z())
                    .color(255, 255, 255, 255)
                    .uv(0, 0)
                    .overlayCoords(OverlayTexture.NO_OVERLAY)
                    .uv2(packedLight)
                    .normal(0, 1, 0)
                    .endVertex();
            vertexPos.transform(new Quaternion(vertexRotAxis, 90, true));
        }

        GL11.glDisable(GL11.GL_STENCIL_TEST);
        
        pose.popPose();

        super.render(entity, entityYaw, partialTicks, pose, buffer, packedLight);
    }