class mrpt::opengl::RenderableProxy

Overview

Base class for GPU-side representations of mrpt::viz::CVisualObject instances.

This is the core abstraction that bridges the abstract scene graph (mrpt::viz) with the actual OpenGL rendering (mrpt::opengl).

Key responsibilities:

GPU Resource Management : Owns OpenGL buffers (VBOs, VAOs, textures)
Compilation : Translates abstract object data into GPU buffers
Incremental Updates : Efficiently updates only changed data
Rendering : Issues OpenGL draw calls using bound shaders

Design pattern: Each concrete CVisualObject type has a corresponding RenderableProxy :

Lifecycle:

Created by CompiledScene during compilation
compile() called once to upload initial data to GPU
updateBuffers() called when the source object data changes (dataVersion())
render() called every frame to draw
Destroyed when source object deleted or scene recompiled

Thread safety:

All methods must be called from the OpenGL context thread
Source object access is read-only (via const pointers)
Source objects are tracked via weak_ptr in CompiledScene

#include <mrpt/opengl/RenderableProxy.h>

class RenderableProxy
{
public:
    // construction

    RenderableProxy();
    RenderableProxy(const RenderableProxy&);
    RenderableProxy(RenderableProxy&&);

    // methods

    virtual void compile(const mrpt::viz::CVisualObject* sourceObj) = 0;
    virtual void updateBuffers(const mrpt::viz::CVisualObject* sourceObj);
    virtual void render(const RenderContext& rc) const = 0;
    virtual std::vector<shader_id_t> requiredShaders() const = 0;
    virtual bool castsShadows() const;
    virtual const char* typeName() const;
    RenderableProxy& operator = (const RenderableProxy&);
    RenderableProxy& operator = (RenderableProxy&&);
};

// direct descendants

class LinesProxyBase;
class PointsProxyBase;
class SkyBoxProxy;
class TrianglesProxyBase;

Methods

virtual void compile(const mrpt::viz::CVisualObject* sourceObj) = 0

Initial compilation: uploads object data to GPU.

This is called once when the proxy is first created. It should:

Create OpenGL buffers (VBOs, VAOs, textures)
Upload initial vertex/color/normal/texture data
Cache any frequently-used values

Must be called from OpenGL context thread

After this call, the proxy should be ready to render

Parameters:

sourceObj

The abstract viz object (read-only access)

virtual void updateBuffers(const mrpt::viz::CVisualObject* sourceObj)

Incremental update: refreshes GPU buffers with changed data.

This is called when the data version of the source object changes (mrpt::viz::CVisualObject::dataVersion()). It should:

Re-upload only the changed data (vertices, colors, etc.)
Be as efficient as possible (don’t recompile everything)

Must be called from OpenGL context thread

Default implementation calls compile() - override for efficiency

Parameters:

sourceObj

The abstract viz object (read-only access)

virtual void render(const RenderContext& rc) const = 0

Renders this object using the provided context.

This is called every frame for visible objects. It should:

Bind appropriate buffers (VAO, VBO, textures)
Set shader uniforms (model matrix, material properties, etc.)
Issue draw calls (glDrawArrays, glDrawElements, etc.)

Must be called from OpenGL context thread

The shader program is already bound when this is called

Common matrices (P, V, M) are already uploaded by CompiledViewport

Parameters:

rc	Rendering context (shader, matrices, lights)

virtual std::vector<shader_id_t> requiredShaders() const = 0

Returns the list of shader programs this object needs.

Most objects use a single shader, but some may use multiple (e.g., different shaders for shadow map pass vs. normal rendering).

Returns:

Vector of shader IDs, typically with 1 element

virtual bool castsShadows() const

Does this object cast shadows?

Used to determine if the object should be rendered during the shadow map generation pass (1st pass of shadow rendering).

Returns:

m_castShadows by default, which follows mrpt::viz::CVisualObject::castShadows() of the object and its parents.

virtual const char* typeName() const

Returns a human-readable type name for this proxy.

Used for debugging and logging.