Add control / update logic

main.c

@@ -3,19 +3,38 @@
 
 #include <linux/input-event-codes.h>
 #include <sys/select.h>
+#include <stdio.h>
+
+#define LIN_PWR 0.0001
+#define ROT_PWR 0.001
 
 #define MAX(a, b) ((a) < (b) ? (b) : (a))
 #define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
 
+static float aspect;
 static bool quit = false;
 
+static struct {
+	int rot;
+	int fwd;
+} input;
+
+static struct {
+	vec2_t pos;
+	vec2_t vel;
+	mat2_t dir;
+	float omg;
+} state;
+
 static const vec2_t ship[] = {
-	{ 0.0, 0.1 },
+	{ 0.0, 0.08 },
 	{ 0.05, -0.1 },
-	{ 0.0, -0.05 },
+	{ 0.0, -0.07 },
 	{ -0.05, -0.1 },
 };
 
+static const vec2_t thrust = { 0, LIN_PWR };
+
 static void key_press_callback(int key)
 {
 	switch (key) {
@@ -23,21 +42,82 @@ static void key_press_callback(int key)
 		quit = true;
 		break;
 
+	case KEY_UP:
+		++input.fwd;
+		break;
+
+	case KEY_LEFT:
+		++input.rot;
+		break;
+	case KEY_RIGHT:
+		--input.rot;
+		break;
+
 	default:
 		break;
 	}
 }
 
+static void key_release_callback(int key)
+{
+	switch (key) {
+	case KEY_Q:
+		quit = true;
+		break;
+
+	case KEY_UP:
+		--input.fwd;
+		break;
+
+	case KEY_LEFT:
+		--input.rot;
+		break;
+	case KEY_RIGHT:
+		++input.rot;
+		break;
+
+	default:
+		break;
+	}
+}
+
+static mat3_t update()
+{
+	state.omg += ROT_PWR * (float)input.rot;
+	state.dir = mat2_mul_mat2(mat2_rotation(state.omg), state.dir);
+
+	const vec2_t acc
+	    = mat2_mul_vec2(state.dir, vec2_scale(thrust, (float)input.fwd));
+	state.vel = vec2_add(state.vel, acc);
+	state.pos = vec2_add(state.pos, state.vel);
+
+	if (state.pos.y > 1)
+		state.pos.y -= 2;
+	else if (state.pos.y < -1)
+		state.pos.y += 2;
+	if (state.pos.x > aspect)
+		state.pos.x -= 2 * aspect;
+	else if (state.pos.x < -aspect)
+		state.pos.x += 2 * aspect;
+
+	return mat3_mul_mat3(
+	    mat3_translation(state.pos), mat2_extend(state.dir));
+}
+
 int main()
 {
 	const int input_fd = input_init();
 	input_on_press(key_press_callback);
+	input_on_release(key_release_callback);
 
 	const renderer_params_t renderer_params = renderer_init();
+	aspect = renderer_params.aspect;
 	const int drm_fd = renderer_params.drm_fd;
 	renderer_clear();
 	renderer_swap();
 
+	state.dir = (mat2_t) { { 1, 0 }, { 0, 1 } };
+
 	const int max_fd = MAX(input_fd, drm_fd);
 	fd_set set;
 
@@ -53,8 +133,11 @@ int main()
 
 		if (FD_ISSET(drm_fd, &set)) {
 			renderer_handle();
+
+			const mat3_t m = update();
+
 			renderer_clear();
-			renderer_draw(ship, NELEMS(ship));
+			renderer_draw(ship, NELEMS(ship), m);
 			renderer_swap();
 		}
 	}

maths.c

@@ -1,15 +1,82 @@
 #include "maths.h"
 
+#include <math.h>
+
+vec2_t vec2_add(vec2_t v1, vec2_t v2)
+{
+	return (vec2_t) { v1.x + v2.x, v1.y + v2.y };
+}
+
+vec2_t vec2_scale(vec2_t v, float s)
+{
+	return (vec2_t) { s * v.x, s * v.y };
+}
+
 vec3_t vec2_extend(vec2_t v)
 {
 	return (vec3_t) { v.x, v.y, 1 };
 }
 
+mat2_t mat2_rotation(float theta)
+{
+	return (mat2_t) {
+		{ cosf(theta), sinf(theta) },
+		{ -sinf(theta), cosf(theta) },
+	};
+}
+
+vec2_t mat2_mul_vec2(mat2_t m, vec2_t v)
+{
+	return (vec2_t) {
+		m.x.x * v.x + m.y.x * v.y,
+		m.x.y * v.x + m.y.y * v.y,
+	};
+}
+
+mat2_t mat2_mul_mat2(mat2_t m1, mat2_t m2)
+{
+#define ELEM(i, j) m1.x.j *m2.i.x + m1.y.j *m2.i.y
+	return (mat2_t) {
+		{ ELEM(x, x), ELEM(x, y) },
+		{ ELEM(y, x), ELEM(y, y) },
+	};
+#undef ELEM
+}
+
+mat3_t mat2_extend(mat2_t m)
+{
+	return (mat3_t) {
+		{ m.x.x, m.x.y, 0 },
+		{ m.y.x, m.y.y, 0 },
+		{ 0, 0, 1 },
+	};
+}
+
+mat3_t mat3_translation(vec2_t v)
+{
+	return (mat3_t) {
+		{ 1, 0, 0 },
+		{ 0, 1, 0 },
+		{ v.x, v.y, 1 },
+	};
+}
+
 vec3_t mat3_mul_vec3(mat3_t m, vec3_t v)
 {
 	return (vec3_t) {
-		.x = m.x.x * v.x + m.y.x * v.y + m.z.x * v.z,
-		.y = m.x.y * v.x + m.y.y * v.y + m.z.y * v.z,
-		.z = m.x.z * v.x + m.y.z * v.y + m.z.z * v.z,
+		m.x.x * v.x + m.y.x * v.y + m.z.x * v.z,
+		m.x.y * v.x + m.y.y * v.y + m.z.y * v.z,
+		m.x.z * v.x + m.y.z * v.y + m.z.z * v.z,
 	};
 }
+
+mat3_t mat3_mul_mat3(mat3_t m1, mat3_t m2)
+{
+#define ELEM(i, j) m1.x.j *m2.i.x + m1.y.j *m2.i.y + m1.z.j *m2.i.z
+	return (mat3_t) {
+		{ ELEM(x, x), ELEM(x, y), ELEM(x, z) },
+		{ ELEM(y, x), ELEM(y, y), ELEM(y, z) },
+		{ ELEM(z, x), ELEM(z, y), ELEM(z, z) },
+	};
+#undef ELEM
+}

maths.h

@@ -1,24 +1,35 @@
 #ifndef MATHS_H
 #define MATHS_H
 
+#define PI 3.14159265358979323846264
+
 typedef struct {
-	float x;
-	float y;
+	float x, y;
 } vec2_t;
 
 typedef struct {
-	float x;
-	float y;
-	float z;
+	vec2_t x, y;
+} mat2_t;
+
+typedef struct {
+	float x, y, z;
 } vec3_t;
 
 typedef struct {
-	vec3_t x;
-	vec3_t y;
-	vec3_t z;
+	vec3_t x, y, z;
 } mat3_t;
 
+vec2_t vec2_add(vec2_t v1, vec2_t v2);
+vec2_t vec2_scale(vec2_t v, float s);
 vec3_t vec2_extend(vec2_t v);
+
+mat2_t mat2_rotation(float theta);
+vec2_t mat2_mul_vec2(mat2_t m, vec2_t v);
+mat2_t mat2_mul_mat2(mat2_t m1, mat2_t m2);
+mat3_t mat2_extend(mat2_t m);
+
+mat3_t mat3_translation(vec2_t v);
 vec3_t mat3_mul_vec3(mat3_t m, vec3_t v);
+mat3_t mat3_mul_mat3(mat3_t m1, mat3_t m2);
 
 #endif

renderer.c

@@ -143,11 +143,12 @@ void renderer_swap()
 	back = (back + 1) & 1;
 }
 
-void renderer_draw(const vec2_t *vs, unsigned count)
+void renderer_draw(const vec2_t *vs, unsigned count, mat3_t model)
 {
+	mat3_t transform = mat3_mul_mat3(view, model);
 	assert(count < MAX_VERTS_PER_DRAW);
 	for (unsigned i = 0; i < count; ++i)
-		vert_buf[i] = mat3_mul_vec3(view, vec2_extend(vs[i]));
+		vert_buf[i] = mat3_mul_vec3(transform, vec2_extend(vs[i]));
 	for (unsigned i = 1; i < count; ++i)
 		draw_line(vert_buf[i - 1], vert_buf[i]);
 	draw_line(vert_buf[count - 1], vert_buf[0]);

renderer.h

@@ -17,6 +17,6 @@ void renderer_handle();
 void renderer_clear();
 void renderer_swap();
 
-void renderer_draw(const vec2_t *vs, unsigned count);
+void renderer_draw(const vec2_t *vs, unsigned count, mat3_t model);
 
 #endif