examples

commit 37e6ac5b19048e4bd2e0a220cce26fb1ab5da611
parent cf735b6b145557a74db354879fc3c94593106b3d
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Sat, 22 Jun 2024 11:06:50 +0100

sdl-gl: Drag objects around

Diffstat:
M
src/sdl-gl.cpp
 | 
82
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------

1 file changed, 60 insertions(+), 22 deletions(-)
diff --git a/src/sdl-gl.cpp b/src/sdl-gl.cpp
@@ -8,13 +8,12 @@
 
 #include "coroutine_owner.hpp"
 
+#include <algorithm>
 #include <cassert>
 #include <exception>
 #include <numbers>
 #include <print>
-
-#define ARRAY_SIZE(a) (sizeof(a) / sizeof(*(a)))
-#define ARRAY_SSIZE(a) ((ssize_t)ARRAY_SIZE(a))
+#include <vector>
 
 extern "C" char const* __asan_default_options() { return "detect_leaks=0"; }
 
@@ -174,28 +173,38 @@ point pan = {1, 0};
 
 point mouse_pos;
 
+struct object
+{
+	point pos;
+	rgb col;
+} objs[] = {
+	{{0, 0}, {.7,.2,.2}},
+	{{4, 0}, {.2,.7,.2}},
+	{{0, 5}, {.2,.2,.7}},
+};
+
+std::vector<point> shape;
+
 void presentScene(void)
 {
 	static double turns = 0;
 	turns += 1./60/4;
 	rotor r = rotor::angle(turns);
-	static point const square[4] = {{-1, -1}, {-1, 1}, {1, -1}, {1, 1}};
-	point objs[] = {{0, 0}, {4, 0}, {0, 5}};
 
 	float x_scale = (float)screen_height / screen_width;
 
 	glClearColor(0, 0, 0, 1);
 	glClear(GL_COLOR_BUFFER_BIT);
 	circle mouse_area{mouse_pos, 1};
-	for (auto op : objs) {
-		if (mouse_area.colliding(op))
-			glColor3d(1,1,0);
+	for (auto& op : objs) {
+		if (mouse_area.colliding(op.pos))
+			glColor3d(op.col.r + .25,op.col.g + .25,op.col.b + .25);
 		else
-			glColor3d(.5,.5,.5);
+			glColor3f(op.col.r, op.col.g, op.col.b);
 
-		glBegin(GL_TRIANGLE_STRIP);
-		for (auto& p : square) {
-			auto pp = (p * r + pan + op) * scale;
+		glBegin(GL_TRIANGLE_FAN);
+		for (auto& p : shape) {
+			auto pp = (p * r + pan + op.pos) * scale;
 			glVertex2f(pp.x * x_scale, pp.y);
 		}
 		glEnd();
@@ -249,20 +258,41 @@ coroutine_task mouse_task()
 	for (;;)
 	{
 		SDL_MouseButtonEvent const& e = co_await click_event;
-		if (e.button != SDL_BUTTON_RIGHT)
-			continue;
-
 		point drag_pos = pan - mouse_to_local(e.x, e.y);
-
-		for (;;)
+		switch (e.button)
+		{
+		case SDL_BUTTON_RIGHT:
 		{
-			SDL_Event const& e2 = co_await motion_or_release_event;
-			if (e2.type == SDL_MOUSEMOTION)
-				pan = drag_pos + mouse_to_local(e2.motion.x, e2.motion.y);
-			else if (auto& b = e2.button; b.button == SDL_BUTTON_RIGHT)
+			for (;;)
+			{
+				SDL_Event const& e2 = co_await motion_or_release_event;
+				if (e2.type == SDL_MOUSEMOTION)
+					pan = drag_pos + mouse_to_local(e2.motion.x, e2.motion.y);
+				else if (auto& b = e2.button; b.button == SDL_BUTTON_RIGHT)
+					break;
+			}
+			break;
+		}
+		case SDL_BUTTON_LEFT:
+		{
+			circle mouse_area{mouse_pos, 1};
+			auto obj = std::ranges::find_if(objs, [drag_pos, mouse_area](auto const& o){return mouse_area.colliding(o.pos);});
+			if (obj == std::end(objs))
 				break;
+			std::swap(obj->col.r, obj->col.g);
+			std::swap(obj->col.g, obj->col.b);
+			drag_pos = obj->pos - mouse_to_local(e.x, e.y);
+			for (;;)
+			{
+				SDL_Event const& e2 = co_await motion_or_release_event;
+				if (e2.type == SDL_MOUSEMOTION)
+					obj->pos = drag_pos + mouse_to_local(e2.motion.x, e2.motion.y);
+				else if (auto& b = e2.button; b.button == SDL_BUTTON_LEFT)
+					break;
+			}
+			break;
+		}
 		}
-
 	}
 }
 
@@ -322,8 +352,16 @@ void doInput()
 	}
 }
 
+void init_shape()
+{
+	shape.emplace_back(0,0);
+	for (int i = 0; i <= 8; ++i)
+		shape.push_back(point{1, 0} * rotor::angle((float)i / 8));
+}
+
 int main()
 {
+	init_shape();
 	mouse_task();
 	initSDL();
 	atexit(SDL_Quit);