Particle system

particle.c

@@ -0,0 +1,80 @@
+
+#include "particle.h"
+#include "types.h"
+#include "util/tree.h"
+#include "util/vector.h"
+#include <stdio.h>
+
+
+System_Particle *particle_NewSystem(App *super) {
+	System_Particle *sys = zero_malloc(sizeof(System_Particle));
+
+	sys->super       = super;
+	sys->parts       = tree_Create(sizeof(Particle));
+	sys->deleted_ids = vector_Create(sizeof(uintptr_t));
+	sys->maxID       = 0;
+	return sys;
+}
+void particle_DeleteSystem(System_Particle *sys) {
+	tree_Destroy(sys->parts);
+	vector_Destroy(sys->deleted_ids);
+	free(sys);
+}
+
+
+static void _particle_AdvancePart(System_Particle *sys, Particle *p, Duration deltaTime) {
+	p->size -= p->sizedec * duration_Seconds(deltaTime);
+	if ((p->tolive.microseconds != 0 &&
+		 time_Since(p->addtime).microseconds > p->tolive.microseconds) ||
+		p->size < EPS) { // vanished
+		particle_Delete(sys, p->id);
+		return;
+	}
+
+	// Move
+	Vec2 delta = vec2_Scale(p->vec, duration_Seconds(deltaTime));
+	p->pos     = vec2_Add(p->pos, delta);
+	// Move slower
+	Vec2 delta_vec = vec2_Scale(p->vec, -p->vec_friction);
+	p->vec         = vec2_Add(p->vec, delta_vec);
+}
+
+void particle_Advance(System_Particle *sys, Duration deltaTime) {
+	// Clear particles marked as deleted
+	for (int i = 0; i < vector_Size(sys->deleted_ids); i++) {
+		uintptr_t  id = *(uintptr_t *)vector_At(sys->deleted_ids, i);
+		tree_Node *n  = tree_FindNode(sys->parts, id);
+		if (n != NULL)
+			tree_Delete(sys->parts, n);
+		else
+			fprintf(stderr, "[particle_Delete][WARN] Missing particle ID [%d]\n", id);
+	}
+	vector_Clear(sys->deleted_ids);
+
+	for (tree_Node *i = tree_FirstNode(sys->parts);
+		 i != NULL;
+		 i = tree_Node_Next(i)) {
+		Particle *p = (Particle *)i->data;
+		_particle_AdvancePart(sys, p, deltaTime);
+	}
+}
+
+void particle_Delete(System_Particle *sys, uintptr_t id) {
+	vector_Push(sys->deleted_ids, &id);
+}
+
+
+void particle_Emit(System_Particle *sys, Vec2 pos, Vec2 vec, double vec_friction, double size, double sizedec, Duration tolive, const FillMode *fill) {
+	uintptr_t id = ++sys->maxID;
+	Particle *p  = tree_Insert(sys->parts, id, NULL);
+	memset(p, 0, sizeof(Particle));
+	p->id           = id;
+	p->addtime      = time_Now();
+	p->tolive       = tolive;
+	p->pos          = pos;
+	p->vec          = vec;
+	p->vec_friction = vec_friction;
+	p->size         = size;
+	p->sizedec      = sizedec;
+	p->mode         = fill;
+}

particle.h

@@ -0,0 +1,52 @@
+#pragma once
+
+#include "types.h"
+#include "render_util.h"
+#include "util/tree.h"
+#include "util/vector.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+// A particle instance.
+typedef struct {
+	uintptr_t id;            // ID.
+	double    size, sizedec; // Diameter & decrease speed, size=0 and the particle is removed
+	Duration  tolive;        // Time desiginated to live, 0 for forever
+	TimePoint addtime;       // Time when this particle is added
+
+	Vec2   pos, vec;     // Center & Speed
+	double vec_friction; // Friction, fraction of Vec per second
+
+	const FillMode *mode; // Fill Modes, NULL for default mode (solid fill)
+} Particle;
+
+
+typedef struct _App App;
+
+// Particle system.
+typedef struct {
+	App           *super;
+	tree_Tree     *parts; // uintptr_t -> struct Particle
+	vector_Vector *deleted_ids;
+	uintptr_t      maxID;
+} System_Particle;
+
+System_Particle *particle_NewSystem(App *super);
+void             particle_DeleteSystem(System_Particle *sys);
+
+void particle_Advance(System_Particle *sys, Duration deltaTime);
+void particle_Render(System_Particle *sys);
+
+
+// Emit a particle here.
+void particle_Emit(System_Particle *sys, Vec2 pos, Vec2 vec, double vec_friction, double size, double sizedec, Duration tolive, const FillMode *fill);
+void particle_Delete(System_Particle *sys, uintptr_t id);
+
+
+#ifdef __cplusplus
+}
+#endif

particle_render.cpp

@@ -0,0 +1,25 @@
+
+#include "camera.h"
+#include "particle.h"
+#include "app.h"
+#include "render_util.h"
+#include "util/assert.h"
+#include <easyx.h>
+
+
+extern "C" {
+
+void particle_Render(System_Particle *sys) {
+	ASSERT(sys->super->camera && "particle_Render called without a Camera system");
+	System_Camera *cam = sys->super->camera;
+
+	for (tree_Node *i = tree_FirstNode(sys->parts);
+		 i != NULL;
+		 i = tree_Node_Next(i)) {
+		Particle *p = (Particle *)i->data;
+
+		render_SetModes(*p->mode, p->addtime);
+		render_FillCircleW(sys->super, p->pos, p->size);
+	}
+}
+}

render_util.cpp

@@ -47,13 +47,20 @@ void render_DrawText(int x, int y, const char *str) {
 }
 
 
-const FillMode render_DefaultMode = {
+const FillMode render_ModeDefault = {
 	.rop2     = R2_COPYPEN,
 	.style    = BS_SOLID,
 	.hatch    = 0,
 	.rotate   = {.microseconds = 0},
 	.dissolve = {.microseconds = 0},
 	.fadein   = false};
+const FillMode render_ModeInverse = {
+	.rop2     = R2_NOT,
+	.style    = BS_SOLID,
+	.hatch    = 0,
+	.rotate   = {.microseconds = 0},
+	.dissolve = {.microseconds = 0},
+	.fadein   = false};
 
 
 void render_SetModes(FillMode mode, TimePoint since) {

render_util.h

@@ -49,7 +49,13 @@ typedef struct {
 //     rop2 = R2_COPYPEN,
 //     style = BS_SOLID,
 //     others = 0
-extern const FillMode render_DefaultMode;
+extern const FillMode render_ModeDefault;
+
+// Fill mode that inverses the screen.
+//     rop2 = R2_NOT,
+//     style = BS_SOLID,
+//     others = 0
+extern const FillMode render_ModeInverse;
 
 typedef struct _App App;
 

types.h

@@ -4,6 +4,7 @@
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
+#include <math.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -60,8 +61,12 @@ typedef struct {
 	int64_t microseconds;
 } Duration;
 
-static inline double duration_Seconds(const Duration t) { return ((double)t.microseconds) / 1000000.0; }
-static inline double duration_Milliseconds(const Duration t) { return ((double)t.microseconds) / 1000.0; }
+static inline double   duration_Seconds(const Duration t) { return ((double)t.microseconds) / 1000000.0; }
+static inline double   duration_Milliseconds(const Duration t) { return ((double)t.microseconds) / 1000.0; }
+static inline Duration duration_FromSeconds(double seconds) {
+	Duration d = {.microseconds = (int64_t)round(seconds * 1000.0 * 1000.0)};
+	return d;
+}
 // This function has a precision of at most 1ms under Windows. Sad
 void duration_Sleep(const Duration t);