separation to vec.h, generic vector ops, camera class and its usage for spatial rendering

CMakeLists.txt

@@ -36,16 +36,16 @@ set(SOURCE_FILES
         third-party/stb/stb_vorbis.c
         third-party/glad/src/glad.c
 
-        src/config.h
-        src/context.h
-        src/context.c
         src/main.c
-        src/audio.c
+        src/config.h
+        src/context.c src/context.h
+        src/audio.c src/audio.h
         src/util.c src/util.h
         src/rendering.c src/rendering.h
         src/textures.c src/textures.h
         src/input.c src/input.h
         src/text.c src/text.h
+        src/camera.c src/camera.h
         src/game_api.h
 
         src/game/game.c src/game/game.h

src/camera.c

@@ -0,0 +1,27 @@
+#include "camera.h"
+
+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);
+
+    t_matrix4 result;
+
+    result.row[0].x = r.x;
+    result.row[0].y = u.x;
+    result.row[0].z =-f.x;
+    result.row[1].x = r.y;
+    result.row[1].y = u.y;
+    result.row[1].z =-f.y;
+    result.row[2].x = r.z;
+    result.row[2].y = u.z;
+    result.row[2].z =-f.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[0].w = result.row[1].w = result.row[2].w = 0.0f;
+    result.row[3].w = 1.0f;
+
+    return result;
+}

src/camera.h

@@ -0,0 +1,15 @@
+#ifndef CAMERA_H
+#define CAMERA_H
+
+#include "util.h"
+
+/* first person camera class */
+typedef struct camera {
+	t_fvec3 pos;		/* eye position */
+	t_fvec3 target;		/* target point */
+	t_fvec3 up;			/* normalized up vector */
+} t_camera;
+
+t_matrix4 camera_look_at(const t_camera *camera);
+
+#endif

src/game/scenes/ingame.c

@@ -11,6 +11,15 @@ 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 } };
+
+    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;
+
+    push_camera(&cam);
+
     push_sprite_ex((t_frect){ .x = 32, .y = 64, .w = 64, .h = 64 }, (t_push_sprite_args){
         .path = "/assets/light.png",
         .color = (t_color){255, 0, 0, 255}, });

src/rendering.c

@@ -13,6 +13,10 @@
 #include <tgmath.h>
 
 
+/* TODO: have a default initialized one */
+static t_matrix4 camera_projection;
+
+
 void render_queue_clear(void) {
     /* since i don't intend to free the queues, */
     /* it's faster and simpler to just "start over" */
@@ -160,7 +164,7 @@ void render(void) {
 
     {
         glMatrixMode(GL_PROJECTION);
-        glLoadIdentity();
+        glLoadMatrixf(&camera_projection.row[0].x);
 
         glMatrixMode(GL_MODELVIEW);
         glLoadIdentity();
@@ -168,6 +172,9 @@ void render(void) {
         render_space();
     }
 
+    /* TODO: only do it when transition between spaces is needed */
+    glClear(GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
+
     {
         glMatrixMode(GL_PROJECTION);
         glLoadIdentity();
@@ -181,3 +188,8 @@ void render(void) {
 
     SDL_GL_SwapWindow(ctx.window);
 }
+
+void push_camera(const t_camera *const camera) {
+    /* TODO: skip recaulculating if it's the same? */
+    camera_projection = camera_look_at(camera);
+}

src/rendering.h

@@ -2,6 +2,7 @@
 #define RENDERING_H
 
 #include "util.h"
+#include "camera.h"
 
 #include <SDL2/SDL.h>
 
@@ -63,6 +64,9 @@ void unfurl_triangle(const char *path,
 //                      t_fvec2 scaling,
 //                      t_frect uvs);
 
+/* pushes a camera state to be used for all future unfurl_* commands */
+void push_camera(const t_camera *camera);
+
 /* renders the background, then the primitives in all render queues */
 void render(void);
 

src/rendering/circles.h

@@ -3,8 +3,8 @@
 #define CIRCLES_H
 
 #include "../util.h"
-#include "internal_api.h"
 #include "../context.h"
+#include "internal_api.h"
 
 #include <SDL2/SDL.h>
 #include <stb_ds.h>

src/rendering/sprites.h

@@ -7,6 +7,7 @@
 #include "../context.h"
 #include "../util.h"
 #include "quad_element_buffer.h"
+#include "internal_api.h"
 
 #include <stb_ds.h>
 

src/rendering/triangles.h

@@ -4,6 +4,7 @@
 
 #include "../textures.h"
 #include "../context.h"
+#include "internal_api.h"
 
 #include <stb_ds.h>
 
@@ -66,6 +67,8 @@ static void draw_uncolored_space_traingle_batch(struct mesh_batch *batch,
         t_rect srcrect = textures_get_srcrect(&ctx.texture_cache, texture_key);
         t_rect dims    = textures_get_dims(&ctx.texture_cache, texture_key);
 
+        /* TODO: fast path for uvs mapped directly on srcrect corners? */
+
         const float wr = (float)srcrect.w / (float)dims.w;
         const float hr = (float)srcrect.h / (float)dims.h;
         const float xr = (float)srcrect.x / (float)dims.w;

src/util.c

@@ -194,21 +194,6 @@ t_fvec2 frect_center(t_frect rect) {
 }
 
 
-t_fvec2 fvec2_from_vec2(t_vec2 vec) {
-    return (t_fvec2) {
-        .x = (float)vec.x,
-        .y = (float)vec.y,
-    };
-}
-
-t_fvec2 fvec2_from_shvec2(t_shvec2 vec) {
-    return (t_fvec2) {
-        .x = (float)vec.x,
-        .y = (float)vec.y,
-    };
-}
-
-
 void tick_timer(int *value) {
     *value = MAX(*value - 1, 0);
 }

src/util.h

@@ -1,6 +1,7 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#include "vec.h"
 
 #include <SDL2/SDL.h>
 #include <physfs.h>
@@ -78,40 +79,13 @@ _Alignas(4)
 } t_color;
 
 
-/* a point in some space (integer) */
-typedef struct vec2 {
-    int x, y;
-} t_vec2;
-
-
-/* a point in some space (floating point) */
-typedef struct fvec2 {
-_Alignas(8)
-    float x;
-    float y;
-} t_fvec2;
-
-
-/* a point in some three dimension space (floating point) */
-/* y goes up, x goes to the right */
-typedef struct fvec3 {
-_Alignas(8)
-    float x;
-    float y;
-    float z;
-} t_fvec3;
-
-
-/* a point in some space (short) */
-typedef struct shvec2 {
-    short x, y;
-} t_shvec2;
-
-
 /* a rectangle with the origin at the upper left (integer) */
 typedef struct rect {
-    int x, y;
-    int w, h;
+_Alignas(16)
+    int32_t x;
+    int32_t y;
+    int32_t w;
+    int32_t h;
 } t_rect;
 
 
@@ -135,15 +109,9 @@ t_frect to_frect(t_rect rect);
 t_fvec2 frect_center(t_frect rect);
 
 
-/* aren't macros to prevent double evaluation with side effects */
-/* maybe could be inlined? i hope LTO will resolve this */
-t_fvec2 fvec2_from_vec2(t_vec2 vec);
-t_fvec2 fvec2_from_shvec2(t_shvec2 vec);
-
-#define m_to_fvec2(p_any_vec2) (_Generic((p_any_vec2),          \
-                                    t_vec2:   fvec2_from_vec2,  \
-                                    t_shvec2: fvec2_from_shvec2 \
-                                )(p_any_vec2))
+typedef struct matrix4 {
+    t_fvec4 row[4];
+} t_matrix4;
 
 
 /* decrements an lvalue (which should be an int), stopping at 0 */

src/vec.h

@@ -0,0 +1,121 @@
+#ifndef VEC_H
+#define VEC_H
+
+#include <stdint.h>
+#include <math.h>
+
+
+/* a point in some space (integer) */
+typedef struct vec2 {
+_Alignas(8)
+    int32_t x;
+    int32_t y;
+} t_vec2;
+
+
+/* a point in some space (floating point) */
+typedef struct fvec2 {
+_Alignas(8)
+    float x;
+    float y;
+} t_fvec2;
+
+
+/* a point in some three dimension space (floating point) */
+/* y goes up, x goes to the right */
+typedef struct fvec3 {
+_Alignas(16)
+    float x;
+    float y;
+    float z;
+} t_fvec3;
+
+
+/* a point in some three dimension space (floating point) */
+/* y goes up, x goes to the right */
+typedef struct fvec4 {
+_Alignas(16)
+    float x;
+    float y;
+    float z;
+    float w;
+} t_fvec4;
+
+
+/* a point in some space (short) */
+typedef struct shvec2 {
+_Alignas(4)
+    int16_t x;
+    int16_t y;
+} t_shvec2;
+
+
+/* aren't macros to prevent double evaluation with side effects */
+/* maybe could be inlined? i hope LTO will resolve this */
+static inline t_fvec2 fvec2_from_vec2(t_vec2 vec) {
+    return (t_fvec2) {
+        .x = (float)vec.x,
+        .y = (float)vec.y,
+    };
+}
+
+static inline t_fvec2 fvec2_from_shvec2(t_shvec2 vec) {
+    return (t_fvec2) {
+        .x = (float)vec.x,
+        .y = (float)vec.y,
+    };
+}
+
+static inline t_fvec3 fvec3_sub(t_fvec3 a, t_fvec3 b) {
+    return (t_fvec3) { a.x - b.x, a.y - b.y, a.z - b.z };
+}
+
+static inline t_fvec3 fvec3_scale(t_fvec3 a, float s) {
+    return (t_fvec3) { a.x * s, a.y * s, a.z * s };
+}
+
+static inline float fvec3_dot(t_fvec3 a, t_fvec3 b) {
+    return a.x * b.x + a.x * b.x + a.z * b.z;
+}
+
+static inline t_fvec3 fvec3_cross(t_fvec3 a, t_fvec3 b) {
+    return (t_fvec3) {
+        a.y * b.z - a.z * b.y,
+        a.z * b.x - a.x * b.z,
+        a.x * b.y - a.y * b.x,
+    };
+}
+
+/* TODO: fast_sqrt version? */
+static inline t_fvec3 fvec3_norm(t_fvec3 a) {
+    const float n = sqrtf(fvec3_dot(a, a));
+    /* TODO: do we need truncating over epsilon as cglm does? */
+    return fvec3_scale(a, 1.0f / n);
+}
+
+#define m_to_fvec2(p_any_vec2) (_Generic((p_any_vec2),          \
+                                    t_vec2:   fvec2_from_vec2,  \
+                                    t_shvec2: fvec2_from_shvec2 \
+                                )(p_any_vec2))
+
+#define m_vec_sub(p_any_vec0, p_any_vec1) (_Generic((p_any_vec0),   \
+                                    t_fvec3:   fvec3_sub            \
+                                )(p_any_vec0, p_any_vec1))
+
+#define m_vec_scale(p_any_vec, p_any_scalar) (_Generic((p_any_vec),     \
+                                    t_fvec3:   fvec3_scale              \
+                                )(p_any_vec, p_any_scalar))
+
+#define m_vec_dot(p_any_vec0, p_any_vec1) (_Generic((p_any_vec0),   \
+                                    t_fvec3:   fvec3_dot            \
+                                )(p_any_vec0, p_any_vec1))
+
+#define m_vec_cross(p_any_vec0, p_any_vec1) (_Generic((p_any_vec0),     \
+                                    t_fvec3:   fvec3_cross              \
+                                )(p_any_vec0, p_any_vec1))
+
+#define m_vec_norm(p_any_vec) (_Generic((p_any_vec),            \
+                                    t_fvec3:   fvec3_norm       \
+                                )(p_any_vec))
+
+#endif