proc-nodes / src / gpu / gpu_compiler.h

#ifndef PROC_NODES_GPU_COMPILER_H
#define PROC_NODES_GPU_COMPILER_H

#include "../graph/proc_node.h"
#include <godot_cpp/classes/rendering_device.hpp>
#include <godot_cpp/variant/rid.hpp>

namespace godot {

struct GpuBatch {
	int first_index = 0; // Index into ExecutionPlan::execution_order
	int node_count = 0; // Number of consecutive nodes in this batch
	// THE NODES EMITTED INTO THIS SHADER, in topological order, ending with the
	// geometry node that writes `pos`. Everything before it is a value/field
	// producer whose arithmetic is inlined rather than computed on the CPU and
	// squeezed through a push constant.
	Vector<int> fused_nodes;
	RID shader; // Compiled compute shader
	RID pipeline; // Compute pipeline
	String compiled_glsl; // For debugging
};

class ProcNodeGraph;

class GpuCompiler {
public:
	// Compile batch of nodes into one GLSL compute shader
	static String compile_batch(
			const Vector<Ref<ProcNode>> &p_nodes,
			const Vector<int> &p_node_indices,
			const ProcNodeGraph *p_graph = nullptr);

	// Create RenderingDevice pipeline from GLSL source
	static bool create_pipeline(
			RenderingDevice *p_rd,
			const String &p_glsl_source,
			GpuBatch &r_batch);

	// Destroy pipeline + shader
	static void destroy_pipeline(RenderingDevice *p_rd, GpuBatch &p_batch);

	// Compile graph to a standalone GLSL function for external systems (e.g. dc-terrain)
	// Returns: GLSL code with a function `float proc_density(vec3 pos)` that evaluates
	// the node graph at a world position. Includes noise library if needed.
	// When p_clamp_octaves is true, integer socket defaults (octave counts) are wrapped
	// with min(N, pn_max_octaves) so an external caller can enforce Nyquist limits.
	// p_graph is what lets a node resolve its INPUTS: without it the emitter can
	// only bake each node's own socket defaults, which is why values could not
	// travel between nodes at all. See docs/glsl-emitter-design.md.
	static String compile_to_function(
			const Vector<Ref<ProcNode>> &p_nodes,
			const Vector<int> &p_node_indices,
			const String &p_function_name = "proc_density",
			bool p_clamp_octaves = false,
			const ProcNodeGraph *p_graph = nullptr);

	// GLSL noise library (simplex 3D + fBM)
	static String get_erosion_library_glsl();

	// Full shader template with placeholders
	static String get_shader_template();
};

} // namespace godot

#endif // PROC_NODES_GPU_COMPILER_H