texture_origin option for sprite rendering

apps/testgame/scenes/ingame.c

@@ -54,10 +54,11 @@ static void ingame_tick(struct state *state) {
         input_set_mouse_captured(&ctx.input, !input_is_mouse_captured(&ctx.input));
     }
 
-    m_sprite(m_set(path,  "/assets/light.png"),
+    m_sprite(m_set(path,  "/assets/player/baron-walk.png"),
-             m_set(rect,  ((t_frect){ 0, 128, 256, 32 })),
+             m_set(rect,  ((t_frect){ 256, 256, 48, 48 })),
-             m_opt(color, ((t_color){ 255, 0, 0, 255 })),
+             m_opt(color, ((t_color){ 255, 255, 255, 255 })),
-             m_opt(scale, false ));
+             m_opt(scale, false ),
+             m_opt(texture_origin, ((t_fvec2){ ctx.tick_count % 48, ctx.tick_count % 48 })));
 
     m_sprite(m_set(path,  "/assets/light.png"),
              m_set(rect,  ((t_frect){ 48, 64, 64, 64 })),

townengine/macros/option.h

@@ -31,6 +31,10 @@
 /* warn: beware of double evaluation! */
 #define m_or(p_value, p_member, p_default) ((p_value).p_member##_opt_set ? (p_value).p_member##_opt : (p_default))
 
+/* warn: beware of double evaluation! */
+#define m_opt_from(p_member, p_value, p_member_from) .p_member##_opt     = (p_value).p_member_from##_opt, \
+                                                     .p_member##_opt_set = (p_value).p_member_from##_opt_set
+
 #define m_option_list_2(t0, m0) \
         t0 m0##_opt;            \
         bool m0##_opt_set : 1;  \
@@ -72,6 +76,21 @@
         bool m3##_opt_set : 1;                          \
         bool m4##_opt_set : 1;                          \
 
+#define m_option_list_12(t0, m0, t1, m1, t2, m2,        \
+                         t3, m3, t4, m4, t5, m5)        \
+        t0 m0##_opt;                                    \
+        t1 m1##_opt;                                    \
+        t2 m2##_opt;                                    \
+        t3 m3##_opt;                                    \
+        t4 m4##_opt;                                    \
+        t5 m5##_opt;                                    \
+        bool m0##_opt_set : 1;                          \
+        bool m1##_opt_set : 1;                          \
+        bool m2##_opt_set : 1;                          \
+        bool m3##_opt_set : 1;                          \
+        bool m4##_opt_set : 1;                          \
+        bool m5##_opt_set : 1;                          \
+
 #define m_option_list_(p_n, ...) m_concatenate(m_option_list_, p_n)(__VA_ARGS__)
 #define m_option_list(...)       m_option_list_(m_narg(__VA_ARGS__), __VA_ARGS__)
 

townengine/macros/varargcount.h

@@ -3,7 +3,7 @@
 
 #define m_narg(...) m_narg_(__VA_ARGS__, m_rseq_n_())
 #define m_narg_(...) m_arg_n_(__VA_ARGS__) 
-#define m_arg_n_(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, N, ...) N 
+#define m_arg_n_(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, N, ...) N 
-#define m_rseq_n_() 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
+#define m_rseq_n_() 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
 
 #endif

townengine/rendering.h

@@ -14,6 +14,7 @@ typedef struct push_sprite_args {
     t_frect rect;
 
     m_option_list(
+        t_fvec2, texture_origin,
         t_color, color,
         float,   rotation,
         bool,    flip_x,

townengine/rendering/internal_api.h

@@ -1,8 +1,9 @@
 #ifndef RENDERING_INTERNAL_API_H
 #define RENDERING_INTERNAL_API_H
 
-#include "../util.h"
+#include "townengine/textures/internal_api.h"
-#include "../textures/internal_api.h"
+#include "townengine/util.h"
+#include "townengine/macros/option.h"
 
 #include <SDL2/SDL.h>
 #include <glad/glad.h>
@@ -17,6 +18,9 @@ struct sprite_primitive {
     bool flip_x;
     bool flip_y;
     bool repeat;
+
+    m_option_list(
+        t_fvec2, texture_origin )
 };
 
 struct rect_primitive {

townengine/rendering/sprites.h

@@ -70,6 +70,7 @@ void push_sprite(const t_push_sprite_args args) {
         .flip_x = m_or(args, flip_x, false),
         .flip_y = m_or(args, flip_y, false),
         .repeat = !m_or(args, scale, true),
+        m_opt_from(texture_origin, args, texture_origin)
     };
 
     struct primitive_2d primitive = {
@@ -220,6 +221,16 @@ static void render_sprites(const struct primitive_2d primitives[],
                 uv1 = (t_fvec2){ rx *  sprite.flip_x, ry * !sprite.flip_y };
                 uv2 = (t_fvec2){ rx * !sprite.flip_x, ry * !sprite.flip_y };
                 uv3 = (t_fvec2){ rx * !sprite.flip_x, ry *  sprite.flip_y };
+
+                if (m_is_set(sprite, texture_origin)) {
+                    /* displace origin */
+
+                    const float ax = sprite.texture_origin_opt.x / srcrect.w;
+                    const float ay = sprite.texture_origin_opt.y / srcrect.h;
+
+                    uv0.x += ax; uv1.x += ax; uv2.x += ax; uv3.x += ax;
+                    uv0.y += ay; uv1.y += ay; uv2.y += ay; uv3.y += ay;
+                }
             }
 
             t_fvec2 v0, v1, v2, v3;

townengine/vec.h

@@ -74,6 +74,10 @@ 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_fvec2 fvec2_div(t_fvec2 a, t_fvec2 b) {
+    return (t_fvec2) { a.x / b.x, a.y / b.y };
+}
+
 static inline t_fvec2 fvec2_scale(t_fvec2 a, float s) {
     return (t_fvec2) { a.x * s, a.y * s };
 }
@@ -136,6 +140,10 @@ static inline t_fvec3 fvec3_rotate(t_fvec3 v, float angle, t_fvec3 axis) {
                                     t_fvec3:   fvec3_sub            \
                                 )(p_any_vec0, p_any_vec1))
 
+#define m_vec_div(p_any_vec0, p_any_vec1) (_Generic((p_any_vec0),   \
+                                    t_fvec2:   fvec2_div            \
+                                )(p_any_vec0, p_any_vec1))
+
 #define m_vec_scale(p_any_vec, p_any_scalar) (_Generic((p_any_vec),     \
                                     t_fvec2:   fvec2_scale,             \
                                     t_fvec3:   fvec3_scale              \