twn_draw.h: new camera api

apps/demos/scenery/scenes/ingame.c

@@ -24,40 +24,34 @@ static void ingame_tick(State *state) {
     input_bind_action_control("mouse_capture_toggle", CONTROL_ESCAPE);
 
     if (scn->mouse_captured) {
-        const float sensitivity = 0.6f; /* TODO: put this in a better place */
+        const float sensitivity = 0.4f * (float)DEG2RAD; /* TODO: put this in a better place */
         scn->yaw += (float)ctx.mouse_movement.x * sensitivity;
         scn->pitch -= (float)ctx.mouse_movement.y * sensitivity;
-        scn->pitch = clampf(scn->pitch, -89.0f, 89.0f);
-
-        const float yaw_rad = scn->yaw * (float)DEG2RAD;
-        const float pitch_rad = scn->pitch * (float)DEG2RAD;
-
-        scn->cam.target = m_vec_norm(((Vec3){
-            cosf(yaw_rad) * cosf(pitch_rad),
-            sinf(pitch_rad),
-            sinf(yaw_rad) * cosf(pitch_rad)
-        }));
+        scn->pitch = clampf(scn->pitch, (float)-M_PI * 0.49f, (float)M_PI * 0.49f);
     }
 
-    const Vec3 right = m_vec_norm(m_vec_cross(scn->cam.target, scn->cam.up));
+    DrawCameraFromPrincipalAxesResult dir_and_up =
+        draw_camera_from_principal_axes(scn->pos, (float)M_PI_2, scn->roll, scn->pitch, scn->yaw);
+
+    const Vec3 right = m_vec_norm(m_vec_cross(dir_and_up.direction, dir_and_up.up));
     const float speed = 0.04f; /* TODO: put this in a better place */
     if (input_is_action_pressed("player_left"))
-        scn->cam.pos = vec3_sub(scn->cam.pos, m_vec_scale(right, speed));
+        scn->pos = vec3_sub(scn->pos, m_vec_scale(right, speed));
 
     if (input_is_action_pressed("player_right"))
-        scn->cam.pos = vec3_add(scn->cam.pos, m_vec_scale(right, speed));
+        scn->pos = vec3_add(scn->pos, m_vec_scale(right, speed));
 
     if (input_is_action_pressed("player_forward"))
-        scn->cam.pos = vec3_add(scn->cam.pos, m_vec_scale(scn->cam.target, speed));
+        scn->pos = vec3_add(scn->pos, m_vec_scale(dir_and_up.direction, speed));
 
     if (input_is_action_pressed("player_backward"))
-        scn->cam.pos = vec3_sub(scn->cam.pos, m_vec_scale(scn->cam.target, speed));
+        scn->pos = vec3_sub(scn->pos, m_vec_scale(dir_and_up.direction, speed));
 
     if (input_is_action_pressed("player_jump"))
-        scn->cam.pos.y += speed;
+        scn->pos.y += speed;
 
     if (input_is_action_pressed("player_run"))
-        scn->cam.pos.y -= speed;
+        scn->pos.y -= speed;
 
     /* toggle mouse capture with end key */
     if (input_is_action_just_pressed("mouse_capture_toggle"))
@@ -65,14 +59,12 @@ static void ingame_tick(State *state) {
 
     input_set_mouse_captured(scn->mouse_captured);
 
-    draw_camera(&scn->cam);
-
     #define TERRAIN_FREQUENCY 0.1f
 
     for (int ly = 64; ly--;) {
         for (int lx = 64; lx--;) {
-            float x = SDL_truncf(scn->cam.pos.x + 32 - (float)lx);
-            float y = SDL_truncf(scn->cam.pos.z + 32 - (float)ly);
+            float x = SDL_truncf(scn->pos.x + 32 - (float)lx);
+            float y = SDL_truncf(scn->pos.z + 32 - (float)ly);
 
             float d0 = stb_perlin_noise3((float)x       * TERRAIN_FREQUENCY, (float)y       * TERRAIN_FREQUENCY, 0, 0, 0, 0) * 3 - 6;
             float d1 = stb_perlin_noise3((float)(x + 1) * TERRAIN_FREQUENCY, (float)y       * TERRAIN_FREQUENCY, 0, 0, 0, 0) * 3 - 6;
@@ -114,7 +106,6 @@ Scene *ingame_scene(State *state) {
     new_scene->base.tick = ingame_tick;
     new_scene->base.end = ingame_end;
 
-    new_scene->cam = (Camera){ .pos = { 32, 0, 1 }, .up = { 0, 1, 0 }, .fov = (float)M_PI_2 };
     new_scene->mouse_captured = true;
 
     m_audio(m_set(path, "music/mod65.xm"),

apps/demos/scenery/scenes/ingame.h

@@ -12,9 +12,7 @@
 typedef struct SceneIngame {
     Scene base;
 
-    Camera cam;
-
-    /* TODO: put this in a better place */
+    Vec3 pos;
     float yaw;
     float pitch;
     float roll;

include/twn_draw.h

@@ -3,7 +3,6 @@
 
 #include "twn_types.h"
 #include "twn_option.h"
-#include "twn_camera.h"
 #include "twn_engine_api.h"
 
 #include <stdbool.h>
@@ -76,8 +75,21 @@ TWN_API void draw_triangle(char const *path,
 //                       Vec2 scaling,
 //                       Rect uvs);
 
-/* pushes a camera state to be used for all future unfurl_* commands */
-TWN_API void draw_camera(const Camera *camera);
+/* sets a perspective 3d camera to be used for all 3d commands */
+TWN_API void draw_camera(Vec3 position, float fov, Vec3 up, Vec3 direction);
+
+/* same as draw_camera(), but with specific use case */
+/* direction and up vectors are inferred from roll, pitch and yaw parameters (in radians) */
+/* return value is direction and up vectors, so that you can use them in logic (such as controllers) */
+typedef struct DrawCameraFromPrincipalAxesResult {
+    Vec3 direction;
+    Vec3 up;
+} DrawCameraFromPrincipalAxesResult;
+DrawCameraFromPrincipalAxesResult TWN_API draw_camera_from_principal_axes(Vec3 position,
+                                                                          float fov,
+                                                                          float roll,
+                                                                          float pitch,
+                                                                          float yaw);
 
 /* expects '*' masks that will be expanded to 6 names: 'up', 'down', 'east', 'west', 'north' and 'south' */
 TWN_API void draw_skybox(const char *paths);

src/rendering/twn_draw.c

@@ -1,8 +1,9 @@
 #include "twn_draw_c.h"
 #include "twn_draw.h"
 #include "twn_engine_context_c.h"
-#include "twn_camera.h"
+#include "twn_camera_c.h"
 #include "twn_types.h"
+#include "twn_vec.h"
 
 #include <SDL2/SDL.h>
 #include <stb_ds.h>
@@ -382,8 +383,39 @@ void render(void) {
 }
 
 
-void draw_camera(const Camera *const camera) {
-    /* TODO: skip recaulculating if it's the same? */
-    camera_projection_matrix = camera_perspective(camera);
-    camera_look_at_matrix    = camera_look_at(camera);
+void draw_camera(Vec3 position, float fov, Vec3 up, Vec3 direction) {
+    Camera const camera = {
+        .fov = fov,
+        .pos = position,
+        .target = direction,
+        .up = up,
+    };
+    camera_projection_matrix = camera_perspective(&camera);
+    camera_look_at_matrix    = camera_look_at(&camera);
+}
+
+
+/* TODO: https://stackoverflow.com/questions/62493770/how-to-add-roll-in-camera-class */
+DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 position, float fov, float roll, float pitch, float yaw) {
+    (void)roll;
+    float yawc, yaws, pitchc, pitchs;
+    sincosf(yaw, &yaws, &yawc);
+    sincosf(pitch, &pitchs, &pitchc);
+    Camera const camera = {
+        .fov = fov,
+        .pos = position,
+        .target = m_vec_norm(((Vec3){
+            yawc * pitchc,
+            pitchs,
+            yaws * pitchc,
+        })),
+        .up = (Vec3){0, 1, 0},
+    };
+    camera_projection_matrix = camera_perspective(&camera);
+    camera_look_at_matrix    = camera_look_at(&camera);
+
+    return (DrawCameraFromPrincipalAxesResult) {
+        .direction = camera.target,
+        .up = camera.up,
+    };
 }

src/twn_camera.c

@@ -1,4 +1,4 @@
-#include "twn_camera.h"
+#include "twn_camera_c.h"
 #include "twn_vec.h"
 #include "twn_engine_context_c.h"
 

src/twn_camera_c.h

@@ -2,7 +2,6 @@
 #define TWN_CAMERA_H
 
 #include "twn_types.h"
-#include "twn_engine_api.h"
 
 /* TODO: make it cached? */
 /*       for example, perspective matrix only needs recaluclation on FOV change */
@@ -15,8 +14,8 @@ typedef struct Camera {
     float fov;       /* field of view, in radians */
 } Camera;
 
-TWN_API Matrix4 camera_look_at(const Camera *camera);
+Matrix4 camera_look_at(const Camera *camera);
 
-TWN_API Matrix4 camera_perspective(const Camera *const camera);
+Matrix4 camera_perspective(const Camera *const camera);
 
 #endif