From 61c7efc6dd2a036b5d14aa223d06a18cb7d1388e Mon Sep 17 00:00:00 2001
From: dec05eba <dec05eba@protonmail.com>
Date: Tue, 16 Nov 2021 03:54:26 +0100
Subject: Sprite: add rotation and origin

---
 include/mgl/gl.h              |  1 +
 include/mgl/graphics/sprite.h |  6 +++++-
 src/gl.c                      |  1 +
 src/graphics/sprite.c         | 25 +++++++++++++++++++------
 tests/main.c                  | 11 +++++++++--
 5 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/include/mgl/gl.h b/include/mgl/gl.h
index 75bc764..7dc1dd7 100644
--- a/include/mgl/gl.h
+++ b/include/mgl/gl.h
@@ -43,6 +43,7 @@ typedef struct {
     void (*glLoadIdentity)(void);
     void (*glLoadMatrixf)(const float *m);
     void (*glTranslatef)(float x, float y, float z);
+    void (*glRotatef)(float angle, float x, float y, float z);
     void (*glGenBuffers)(int n, unsigned int *buffers);
     void (*glBindBuffer)(unsigned int target, unsigned int buffer);
     void (*glDeleteBuffers)(int n, const unsigned int *buffers);
diff --git a/include/mgl/graphics/sprite.h b/include/mgl/graphics/sprite.h
index 03f81ab..64d9c03 100644
--- a/include/mgl/graphics/sprite.h
+++ b/include/mgl/graphics/sprite.h
@@ -12,15 +12,19 @@ typedef struct {
     mgl_color color;
     mgl_vec2f position;
     mgl_vec2f scale;
+    mgl_vec2f origin; /* top left by default (0, 0) */
+    float rotation; /* in degrees */
 } mgl_sprite;
 
 /* |texture| may be NULL */
-void mgl_sprite_init(mgl_sprite *self, mgl_texture *texture, float x, float y);
+void mgl_sprite_init(mgl_sprite *self, mgl_texture *texture);
 
 /* |texture| may be NULL */
 void mgl_sprite_set_texture(mgl_sprite *self, mgl_texture *texture);
 void mgl_sprite_set_position(mgl_sprite *self, mgl_vec2f position);
 void mgl_sprite_set_color(mgl_sprite *self, mgl_color color);
+void mgl_sprite_set_rotation(mgl_sprite *self, float degrees);
+void mgl_sprite_set_origin(mgl_sprite *self, mgl_vec2f origin);
 void mgl_sprite_draw(mgl_context *context, mgl_sprite *sprite);
 
 #endif /* MGL_SPRITE_H */
diff --git a/src/gl.c b/src/gl.c
index 5999b80..4d8fb58 100644
--- a/src/gl.c
+++ b/src/gl.c
@@ -57,6 +57,7 @@ int mgl_gl_load(mgl_gl *self) {
         { &self->glLoadIdentity, "glLoadIdentity" },
         { &self->glLoadMatrixf, "glLoadMatrixf" },
         { &self->glTranslatef, "glTranslatef" },
+        { &self->glRotatef, "glRotatef" },
         { &self->glGenBuffers, "glGenBuffers" },
         { &self->glBindBuffer, "glBindBuffer" },
         { &self->glDeleteBuffers, "glDeleteBuffers" },
diff --git a/src/graphics/sprite.c b/src/graphics/sprite.c
index 2aecdd1..df3e902 100644
--- a/src/graphics/sprite.c
+++ b/src/graphics/sprite.c
@@ -2,11 +2,13 @@
 #include "../../include/mgl/graphics/texture.h"
 #include "../../include/mgl/mgl.h"
 
-void mgl_sprite_init(mgl_sprite *self, mgl_texture *texture, float x, float y) {
+void mgl_sprite_init(mgl_sprite *self, mgl_texture *texture) {
     self->texture = texture;
     self->color = (mgl_color){ 255, 255, 255, 255 };
-    self->position = (mgl_vec2f){ x, y };
+    self->position = (mgl_vec2f){ 0.0f, 0.0f };
     self->scale = (mgl_vec2f){ 1.0f, 1.0f };
+    self->origin = (mgl_vec2f){ 0.0f, 0.0f };
+    self->rotation = 0.0f;
 }
 
 void mgl_sprite_set_texture(mgl_sprite *self, mgl_texture *texture) {
@@ -21,6 +23,14 @@ void mgl_sprite_set_color(mgl_sprite *self, mgl_color color) {
     self->color = color;
 }
 
+void mgl_sprite_set_rotation(mgl_sprite *self, float degrees) {
+    self->rotation = degrees;
+}
+
+void mgl_sprite_set_origin(mgl_sprite *self, mgl_vec2f origin) {
+    self->origin = origin;
+}
+
 /* TODO: Cache texture bind to not bind texture if its already bound and do not bind texture 0 */
 void mgl_sprite_draw(mgl_context *context, mgl_sprite *sprite) {
     if(!sprite->texture)
@@ -35,18 +45,21 @@ void mgl_sprite_draw(mgl_context *context, mgl_sprite *sprite) {
 
     context->gl.glColor4ub(sprite->color.r, sprite->color.g, sprite->color.b, sprite->color.a);
     mgl_texture_use(sprite->texture);
+    context->gl.glTranslatef(sprite->position.x, sprite->position.y, 0.0f);
+    context->gl.glRotatef(sprite->rotation, 0.0f, 0.0f, 1.0f);
     context->gl.glBegin(GL_QUADS);
         context->gl.glTexCoord2f(0.0f, 0.0f);
-        context->gl.glVertex3f(sprite->position.x, sprite->position.y, 0.0f);
+        context->gl.glVertex3f(-sprite->origin.x * sprite->scale.x, -sprite->origin.y * sprite->scale.y, 0.0f);
 
         context->gl.glTexCoord2f(texture_right, 0.0f);
-        context->gl.glVertex3f(sprite->position.x + sprite->texture->width * sprite->scale.x, sprite->position.y, 0.0f);
+        context->gl.glVertex3f((sprite->texture->width - sprite->origin.x) * sprite->scale.x, -sprite->origin.y * sprite->scale.y, 0.0f);
 
         context->gl.glTexCoord2f(texture_right, texture_bottom);
-        context->gl.glVertex3f(sprite->position.x + sprite->texture->width * sprite->scale.x, sprite->position.y + sprite->texture->height * sprite->scale.y, 0.0f);
+        context->gl.glVertex3f((sprite->texture->width - sprite->origin.x) * sprite->scale.x, (sprite->texture->height - sprite->origin.y) * sprite->scale.y, 0.0f);
 
         context->gl.glTexCoord2f(0.0f, texture_bottom);
-        context->gl.glVertex3f(sprite->position.x, sprite->position.y + sprite->texture->height * sprite->scale.y, 0.0f);
+        context->gl.glVertex3f(-sprite->origin.x * sprite->scale.x, (sprite->texture->height - sprite->origin.y) * sprite->scale.y, 0.0f);
     context->gl.glEnd();
     mgl_texture_use(NULL);
+    context->gl.glLoadIdentity(); /* TODO: Remove, but what about glRotatef above */
 }
diff --git a/tests/main.c b/tests/main.c
index 3dc8c98..f76f384 100644
--- a/tests/main.c
+++ b/tests/main.c
@@ -34,9 +34,16 @@ static void draw(mgl_window *window, void *userdata) {
 
     mgl_shader_program_set_uniform_vec2f(u->shader_program, "resolution", (mgl_vec2f){ u->texture->width, u->texture->height });
 
+    static float rot = 0.0f;
+    rot += 5.0f;
+
     mgl_sprite sprite;
-    mgl_sprite_init(&sprite, u->texture, 100.0f - 10.0f, 0.0f);
+    mgl_sprite_init(&sprite, u->texture);
+    mgl_sprite_set_position(&sprite, (mgl_vec2f){ 100.0f - 10.0f + u->texture->width * 0.5f * 2.0f, u->texture->height * 0.5f * 2.0f });
     mgl_sprite_set_color(&sprite, (mgl_color){255, 255, 255, 128});
+    mgl_sprite_set_rotation(&sprite, rot);
+    mgl_sprite_set_origin(&sprite, (mgl_vec2f){ u->texture->width * 0.5f, u->texture->height * 0.5f });
+    sprite.scale = (mgl_vec2f){ 2.0f, 2.0f };
     mgl_shader_program_use(u->shader_program);
     mgl_sprite_draw(context, &sprite);
     mgl_shader_program_use(NULL);
@@ -213,7 +220,7 @@ int main(int argc, char **argv) {
     if(mgl_texture_init(&texture) != 0)
         return 1;
 
-    if(mgl_texture_load_from_file(&texture, "tests/X11.jpg", &(mgl_texture_load_options){ false, true }) != 0)
+    if(mgl_texture_load_from_file(&texture, "tests/X11.jpg", &(mgl_texture_load_options){ false, false }) != 0)
         return 1;
 
     if(mgl_mapped_file_load("/usr/share/fonts/noto/NotoSans-Regular.ttf", &font_file, &(mgl_memory_mapped_file_load_options){ .readable = true, .writable = false }) != 0)
-- 
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