Don't update xsections if unnecessary.

5 files changed, 57 insertions, 31 deletions

diff --git a/src/physics.c b/src/physics.c
index 3981258..04c655c 100644
--- a/src/physics.c
+++ b/src/physics.c
@@ -34,6 +34,8 @@ void phy_sim_reset(phy_sim *sim)
 
 	sim->time = 0;
 	sim->running = false;
+
+	sim->frame_index = get_time();
 }
 
 int phy_sim_create(phy_sim *sim)
@@ -45,8 +47,8 @@ int phy_sim_create(phy_sim *sim)
 
 	fi = &sim->field_info;
 
-	fi->width = 100;
-	fi->height = 100;
+	fi->width = 50;
+	fi->height = 50;
 	fi->depth = 50;
 	fi->spacing = 1.5e10f / max3(fi->width, fi->height, fi->depth);
 	sim->time_delta = 0.1;
@@ -171,45 +173,58 @@ void phy_sim_step_H(phy_field_info *fi, float *mul_const, float dt,
 	}
 }
 
-void phy_sim_add_sources(phy_sim *sim)
+void phy_sim_add_sources_E(phy_sim *sim)
 {
 	phy_field_info *fi = &sim->field_info;
 	float *E;
 	size_t x, y, z;
 
-	for (z = 1; z < fi->depth - 1; z++)
-	for (y = 15; y < fi->height - 15; y++)
-	for (x = 1; x < fi->width - 1; x++) {
-		float s;
+	x = fi->width / 2;
+	y = fi->height / 2;
+	z = fi->depth / 2;
 
-		E = sim->fields[2].E + z * fi->zstr + y * fi->ystr + x * fi->xstr;
+	E = sim->fields[2].E + z * fi->zstr + y * fi->ystr + x * fi->xstr;
+	E[0] += exp(-0.1f * pow(sim->time - 5.0f, 2)) * 5;
+}
 
-		s = exp(-600.0f * pow((float)x / fi->width - 0.15f, 2));
-		s *= sin(sim->time);
-		//s *= exp(-2.0f * pow(sim->time - 2.0f, 2)) * 1000;
-		E[0] += s;
-	}
+void phy_sim_add_sources_H(phy_sim *sim)
+{
+	phy_field_info *fi = &sim->field_info;
+	float *H;
+	size_t x, y, z;
+
+	x = fi->width / 2;
+	y = fi->height / 2;
+	z = fi->depth / 2;
+
+	H = sim->fields[2].H + z * fi->zstr + y * fi->ystr + x * fi->xstr;
+	H[1] -= exp(-0.1f * pow(sim->time - 4.5f, 2)) * 5;
 }
 
 void phy_sim_step(phy_sim *sim) {
 	phy_field_info *fi = &sim->field_info;
 	phy_field_em *fields = sim->fields, tmp;
 
-	// note: only pointers are rotated, not the entire fields
+
+	phy_sim_step_E(fi, sim->field_mu, sim->time_delta,
+	               fields[2].E, fields[0].E, fields[1].H);
+	phy_sim_add_sources_E(sim);
+	phy_sim_step_H(fi, sim->field_eps, sim->time_delta,
+	               fields[2].H, fields[0].H, fields[1].E);
+	phy_sim_add_sources_H(sim);
+
 	SDL_mutexP(sim->rotate_lock);
+
+	// note: only pointers are rotated, not the entire fields
 	memcpy(&tmp, fields, sizeof(phy_field_em));
 	memcpy(fields, fields + 1, sizeof(phy_field_em));
 	memcpy(fields + 1, fields + 2, sizeof(phy_field_em));
 	memcpy(fields + 2, &tmp, sizeof(phy_field_em));
-	SDL_mutexV(sim->rotate_lock);
+	sim->time += sim->time_delta;
 
-	phy_sim_step_H(fi, sim->field_eps, sim->time_delta,
-	               fields[2].H, fields[0].H, fields[1].E);
-	phy_sim_step_E(fi, sim->field_mu, sim->time_delta,
-	               fields[2].E, fields[0].E, fields[1].H);
-	phy_sim_add_sources(sim);
+	sim->frame_index = get_time();
 
-	sim->time += sim->time_delta;
+	SDL_mutexV(sim->rotate_lock);
 }
 
 void phy_run_command(phy_sim *sim, int number, void *data)
diff --git a/src/physics.h b/src/physics.h
index 92ec6fd..1ce2a9c 100644
--- a/src/physics.h
+++ b/src/physics.h
@@ -35,6 +35,7 @@ typedef struct {
 	bool running;
 	itc_chan ctl;
 	SDL_mutex *rotate_lock;
+	int64_t frame_index; // to avoid re-drawing the same fields
 } phy_sim;
 
 void phy_sim_destroy(phy_sim *sim);
diff --git a/src/renderer.c b/src/renderer.c
index 3c403a0..fb1647b 100644
--- a/src/renderer.c
+++ b/src/renderer.c
@@ -360,13 +360,21 @@ void r_xsection_destroy(r_xsection *xsection)
 }
 
 int r_xsection_update(r_window *rw, r_xsection *xsection,
-                      phy_field_info *fi, float *field,
+                      phy_field_info *fi, float *field, int64_t frame_index,
                       r_xsection_type type, float frac)
 {
 	size_t width, height, x, y, z;
 	uint8_t *pixels;
 	int pitch;
 
+	if (xsection->frame_index &&
+	    xsection->frame_index == frame_index &&
+	    xsection->last_frac == frac &&
+	    xsection->last_type == type)
+		return 0; // nothing's changed
+
+	printf("r_xsection_update: tick %ld\n", frame_index);
+
 	switch (type) {
 	case XSECTION_XY:
 		width = fi->width;
@@ -462,6 +470,9 @@ int r_xsection_update(r_window *rw, r_xsection *xsection,
 
 	xsection->aspect_ratio = (float)width / height;
 
+	xsection->last_frac = frac;
+	xsection->last_type = type;
+	xsection->frame_index = frame_index;
 	return 0;
 }
 
diff --git a/src/renderer.h b/src/renderer.h
index 0c38e6d..ce373df 100644
--- a/src/renderer.h
+++ b/src/renderer.h
@@ -49,12 +49,16 @@ typedef enum {
 typedef struct {
 	SDL_Texture *texture;
 	float aspect_ratio;
+
+	r_xsection_type last_type;
+	float last_frac;
+	int64_t frame_index;
 } r_xsection;
 
 void r_xsection_create(r_xsection *xsection);
 void r_xsection_destroy(r_xsection *xsection);
 int r_xsection_update(r_window *rw, r_xsection *xsection,
-                      phy_field_info *fi, float *field,
+                      phy_field_info *fi, float *field, int64_t frame_index,
                       r_xsection_type type, float frac);
 void r_xsection_draw(r_window *rw, r_xsection *xsection,
                      float x, float y, float w, float h);
diff --git a/src/ui.c b/src/ui.c
index 72a7c7b..700950b 100644
--- a/src/ui.c
+++ b/src/ui.c
@@ -141,11 +141,6 @@ void ui_infof(ui_window *uiw, const char *fmt, ...)
 	uiw->simview.info_time = get_time();
 }
 
-static void ui_simview_set_select(ui_simview *sv, vec2_t sel_2d)
-{
-
-}
-
 void ui_event_window(SDL_Event *event, ui_window *uiw)
 {
 	ui_simview *sv = &uiw->simview;
@@ -300,8 +295,9 @@ void ui_draw_simview_xsection(ui_window *uiw, float *field)
 	vec2_t origin_s, scale_s;
 
 	SDL_mutexP(sim->rotate_lock);
-	r_xsection_update(uiw->rw, &sv->xsection, &sim->field_info,
-	                  field, sv->xsection_type, sv->xsection_frac);
+	r_xsection_update(uiw->rw, &sv->xsection, &sim->field_info, field,
+	                  sim->frame_index, sv->xsection_type,
+	                  sv->xsection_frac);
 	SDL_mutexV(sim->rotate_lock);
 
 	aspect_ratio = sv->xsection.aspect_ratio;
@@ -326,7 +322,6 @@ void ui_draw_simview_xsection(ui_window *uiw, float *field)
 void ui_draw_simview_selection(ui_window *uiw)
 {
 	ui_simview *sv = &uiw->simview;
-	phy_sim *sim = sv->sim;
 	vec2_t select_s;
 
 	if (sv->selecting)