working camera

apps/testgame/scenes/ingame.c

@@ -11,14 +11,14 @@ static void ingame_tick(struct state *state) {
     world_drawdef(scn->world);
     player_calc(scn->player);
 
-    static t_camera cam = { .pos = { 0 }, .target = { 0, 0, -1 }, .up = { 0, -1, 0 }, .fov = (float)M_PI_2 };
+    static t_camera cam = { .pos = { 0, 0, 1 }, .target = { 0, 0, -1 }, .up = { 0, 1, 0 }, .fov = (float)M_PI_2 };
 
     if (input_is_action_pressed(&ctx.input, "player_left"))
         cam.pos.x -= 0.01f;
     if (input_is_action_pressed(&ctx.input, "player_right"))
         cam.pos.x += 0.01f;
     if (input_is_action_pressed(&ctx.input, "player_jump"))
-        cam.pos.z -= 0.01f;
+        cam.pos.z += 0.01f;
 
     m_sprite(m_set(path,  "/assets/light.png"),
              m_set(rect,  ((t_frect){ 48, 64, 64, 64 })),

src/camera.c

@@ -1,27 +1,52 @@
 #include "camera.h"
+#include "context.h"
+
+#include <math.h>
+
+
+#define CAMERA_NEAR_Z 0.1f
+#define CAMERA_FAR_Z 100.0f
+
 
 t_matrix4 camera_look_at(const t_camera *const camera) {
     /* from cglm */
-    const t_fvec3 f = m_vec_norm(m_vec_sub(camera->pos, camera->target));
-    const t_fvec3 r = m_vec_norm(m_vec_cross(f, camera->up));
-    const t_fvec3 u = m_vec_cross(f, r);
+    const t_fvec3 r = m_vec_norm(m_vec_cross(camera->target, camera->up));
+    const t_fvec3 u = m_vec_cross(r, camera->target);
 
     t_matrix4 result;
 
     result.row[0].x =  r.x;
     result.row[0].y =  u.x;
-    result.row[0].z =-f.x;
+    result.row[0].z = -camera->target.x;
     result.row[1].x =  r.y;
     result.row[1].y =  u.y;
-    result.row[1].z =-f.y;
+    result.row[1].z = -camera->target.y;
     result.row[2].x =  r.z;
     result.row[2].y =  u.z;
-    result.row[2].z =-f.z;
+    result.row[2].z = -camera->target.z;
     result.row[3].x = -m_vec_dot(r, camera->pos);
     result.row[3].y = -m_vec_dot(u, camera->pos);
-    result.row[3].z = m_vec_dot(f, camera->pos);
+    result.row[3].z =  m_vec_dot(camera->target, camera->pos);
     result.row[0].w =  result.row[1].w = result.row[2].w = 0.0f;
     result.row[3].w =  1.0f;
 
     return result;
 }
+
+t_matrix4 camera_perspective(const t_camera *const camera) {
+    /* from cglm */
+    t_matrix4 result = {0};
+
+    const float aspect = RENDER_BASE_RATIO;
+
+    const float f  = 1.0f / tanf(camera->fov * 0.5f);
+    const float fn = 1.0f / (CAMERA_NEAR_Z - CAMERA_FAR_Z);
+
+    result.row[0].x =  f / aspect;
+    result.row[1].y =  f;
+    result.row[2].z =  (CAMERA_NEAR_Z + CAMERA_FAR_Z) * fn;
+    result.row[2].w = -1.0f;
+    result.row[3].z =  2.0f * CAMERA_NEAR_Z * CAMERA_FAR_Z * fn;
+
+    return result;
+}

src/camera.h

@@ -3,13 +3,19 @@
 
 #include "util.h"
 
+/* TODO: make it cached */
+/*       for example, perspective matrix only needs recaluclation on FOV change */
+
 /* first person camera class */
 typedef struct camera {
     t_fvec3 pos;        /* eye position */
-	t_fvec3 target;		/* target point */
+    t_fvec3 target;     /* normalized target vector */
     t_fvec3 up;         /* normalized up vector */
+    float fov;        /* field of view, in radians */
 } t_camera;
 
 t_matrix4 camera_look_at(const t_camera *camera);
 
+t_matrix4 camera_perspective(const t_camera *const camera);
+
 #endif

src/rendering.c

@@ -14,7 +14,8 @@
 
 
 /* TODO: have a default initialized one */
-static t_matrix4 camera_projection;
+static t_matrix4 camera_projection_matrix;
+static t_matrix4 camera_look_at_matrix;
 
 
 void render_queue_clear(void) {
@@ -164,10 +165,10 @@ void render(void) {
 
     {
         glMatrixMode(GL_PROJECTION);
-        glLoadMatrixf(&camera_projection.row[0].x);
+        glLoadMatrixf(&camera_projection_matrix.row[0].x);
 
         glMatrixMode(GL_MODELVIEW);
-        glLoadIdentity();
+        glLoadMatrixf(&camera_look_at_matrix.row[0].x);
 
         render_space();
     }
@@ -189,7 +190,8 @@ void render(void) {
     SDL_GL_SwapWindow(ctx.window);
 }
 
-void push_camera(const t_camera *const camera) {
+void set_camera(const t_camera *const camera) {
     /* TODO: skip recaulculating if it's the same? */
-    camera_projection = camera_look_at(camera);
+    camera_projection_matrix = camera_perspective(camera);
+    camera_look_at_matrix = camera_look_at(camera);
 }