Location

include/mop/display.h   — Public types and function declarations
src/core/display.c       — Default construction and viewport get/set
src/core/viewport.c      — pass_overlays() reads display settings each frame

Overview

MopDisplaySettings controls per-viewport debug visualizations: wireframe overlay, vertex normals, bounding boxes, vertex point display, and vertex map coloring. All overlays default to disabled, matching legacy behavior.

Types

MopVertexMapDisplay

typedef enum MopVertexMapDisplay {
    MOP_VTXMAP_NONE    = 0,
    MOP_VTXMAP_UV      = 1,
    MOP_VTXMAP_WEIGHTS = 2,
    MOP_VTXMAP_NORMALS = 3,
    MOP_VTXMAP_CUSTOM  = 4,
} MopVertexMapDisplay;

MopDisplaySettings

typedef struct MopDisplaySettings {
    /* Wireframe overlay */
    bool     wireframe_overlay;
    MopColor wireframe_color;
    float    wireframe_opacity;

    /* Vertex visualization */
    bool     show_normals;
    float    normal_display_length;
    bool     show_bounds;
    bool     show_vertices;
    float    vertex_display_size;

    /* Vertex map coloring */
    MopVertexMapDisplay vertex_map_mode;
    uint32_t            vertex_map_channel;
} MopDisplaySettings;

Functions

mop_display_settings_default

MopDisplaySettings mop_display_settings_default(void);

Returns a MopDisplaySettings value with all overlays disabled and all numeric fields set to their documented defaults. This is the initial state applied during mop_viewport_create. If mop_viewport_get_display is called on a NULL viewport, this function is used internally as the fallback.

mop_viewport_set_display

void mop_viewport_set_display(MopViewport *vp, const MopDisplaySettings *ds);

Copies the provided display settings into the viewport. The settings take effect on the next mop_viewport_render call. Silently returns if either argument is NULL.

mop_viewport_get_display

MopDisplaySettings mop_viewport_get_display(const MopViewport *vp);

Returns a copy of the viewport's current display settings. Returns mop_display_settings_default() if vp is NULL.

Visualization Modes

Wireframe Overlay

When wireframe_overlay is true and the wireframe overlay is enabled in the overlay system, mop_overlay_builtin_wireframe draws triangle edges on top of the shaded scene. wireframe_color controls the line color and wireframe_opacity controls the blend factor. This is distinct from the MOP_RENDER_WIREFRAME render mode, which replaces solid shading entirely.

Normals

When show_normals is true, vertex normal lines are drawn as line segments extending from each vertex position in the normal direction. normal_display_length controls the length of these lines in world units. Useful for debugging lighting issues and verifying model normals.

Bounding Boxes

When show_bounds is true, an axis-aligned bounding box is drawn around each active mesh. The box is computed from the mesh's world-space vertex positions. Helpful for verifying spatial relationships and debugging culling.

Vertex Points

When show_vertices is true, each vertex is rendered as a screen-space point with a diameter of vertex_display_size pixels. This mode aids in inspecting mesh density and vertex distribution.

Vertex Map Coloring

The vertex_map_mode field selects which per-vertex attribute is visualized as surface color:

When vertex_map_mode is MOP_VTXMAP_CUSTOM, the vertex_map_channel field selects which custom attribute index to read (0 = MOP_ATTRIB_CUSTOM0, 1 = MOP_ATTRIB_CUSTOM1, etc.).

Usage

/* Enable wireframe overlay with custom color */
MopDisplaySettings ds = mop_viewport_get_display(vp);
ds.wireframe_overlay = true;
ds.wireframe_color   = (MopColor){ 0.0f, 1.0f, 0.5f, 1.0f };
ds.wireframe_opacity = 0.3f;
mop_viewport_set_display(vp, &ds);

/* Also need to enable the overlay slot */
mop_viewport_set_overlay_enabled(vp, MOP_OVERLAY_WIREFRAME, true);

/* Visualize UV coordinates */
ds.vertex_map_mode = MOP_VTXMAP_UV;
mop_viewport_set_display(vp, &ds);