Hi all. New to modding so this is probably a silly question but I've searched and searched but cannot find any guides or sample code that works for 1.17.1
I have successfully created a client-side only mod that displays the player's coordinates on the screen and am now trying to draw a simple line in the world. Unfortunately, everything I have tried results in nothing displaying or a crash.
My latest crash is

Cannot invoke "net.minecraft.client.renderer.ShaderInstance.setSampler(String, Object)" because "shaderinstance" is null

Here is the code I have so far
 

public class MyRenderType extends RenderType {
    public MyRenderType(String p_173178_, VertexFormat p_173179_, VertexFormat.Mode p_173180_, int p_173181_, boolean p_173182_, boolean p_173183_, Runnable p_173184_, Runnable p_173185_) {
        super(p_173178_, p_173179_, p_173180_, p_173181_, p_173182_, p_173183_, p_173184_, p_173185_);
    }

    private static final LineStateShard THICK_LINES = new LineStateShard(OptionalDouble.of(3.0));

    public static final RenderType OVERLAY_LINES = create("overlay_lines",
            DefaultVertexFormat.POSITION_COLOR,
            VertexFormat.Mode.LINES,
            256,
            true,
            true,
            CompositeState.builder()
                    .setLineState(THICK_LINES)
                    .setLayeringState(VIEW_OFFSET_Z_LAYERING)
                    .setTransparencyState(TRANSLUCENT_TRANSPARENCY)
                    .setTextureState(NO_TEXTURE)
                    .setDepthTestState(NO_DEPTH_TEST)
                    .setCullState(NO_CULL)
                    .setLightmapState(NO_LIGHTMAP)
                    .setWriteMaskState(COLOR_WRITE)
                    .createCompositeState(false)
    );
}

///////////////

@SubscribeEvent
public static void drawLast(RenderWorldLastEvent event) {
    MultiBufferSource.BufferSource buffer = MultiBufferSource.immediate(Tesselator.getInstance().getBuilder());
    VertexConsumer builder = buffer.getBuffer(MyRenderType.OVERLAY_LINES);
    PoseStack matrixStack = event.getMatrixStack();
    Vec3 pos = minecraft.player.position();
    matrixStack.pushPose();
    matrixStack.translate(-pos.x, -pos.y, -pos.z);

    Matrix4f matrix = matrixStack.last().pose();

    // There's also a version of the vertex method that doesn't take matrixStack, I tried that too but it made no difference.
    builder.vertex(matrixStack, (float)-5 + 0.5f, (float)0 + 0.5f, (float)5 + 0.5f)
        .color(1,0,0,1f)
        .endVertex();
    builder.vertex(matrixStack, (float)5 + 0.5f, (float)0 + 0.5f, (float)5 + 0.5f)
        .color(1, 0, 0, 1f)
        .endVertex();

    // I tried adding these lines but it made no difference.
    //RenderSystem.setShaderColor(1.0F, 1.0F, 1.0F, 1.0F);
    //RenderSystem.setShader(GameRenderer::getPositionColorShader);

    buffer.endBatch(); // crashes here
    matrixStack.popPose();
}

Any help is much appreciated

Edited September 7, 20214 yr by Marshall7

you can draw a line with the LevelRenderer, you can look into the StructureBlockEntityRenderer for an example

Do you have a link to some sample code or guide? I cannot seem to find any information about those.
Is my existing code completely wrong? I'd like to understand why my existing code is not working and why it is not right for the job.

5 hours ago, Marshall7 said:

Do you have a link to some sample code or guide?

Look at some vanilla code, I already told you which class you can use

I am trying to find the class you mentioned but StructureBlockEntityRenderer doesn't appear to exist in the vanilla code that I can see. I also cannot find any results on google for either class.
I can see LevelRenderer but so far haven't been able to figure out how to use it or what is wrong with my existing code.

damn I'm stupid the class is called StructureBlockRenderer, if I'm again not correct use your ide to find the class the name should contains "Structure" and "Renderer"

Thank you! I was able to make something appear using LevelRenderer and now I have determined the key thing that was wrong with my original code:
My custom render type needed to include

.setShaderState(RENDERTYPE_LINES_SHADER)

and for some reason I need one or both of
 

RenderSystem.disableDepthTest();
RenderSystem.disableCull();

...if I want to see the line through other blocks.

Look at the PlayerRenderer, the part where the Glowing Effect is rendered, what do you try to achieve?

Thanks I will look at that. I am working on a sort of breadcrumb trail overlay that shows where I've been recently.