render set clip, fix render push vertex

src/render/render_opengl.c

@@ -14,7 +14,6 @@ struct rn_vertex_t {
 
 typedef enum {
     rn_cmd_kind_null,
-    rn_cmd_kind_clear,
     rn_cmd_kind_quad,
     rn_cmd_kind_set_clip,
 } rn_cmd_kind_t;
@@ -104,6 +103,7 @@ rn_cmd_t *rn_get_cmd(rn_cmd_kind_t kind) {
 
 rn_vertex_t *rn_push_vertex(rn_cmd_t *cmd, u32 count) {
     rn_vertex_t *result = cmd->vertex + cmd->len;
+    rn_state.len += count;
     cmd->len += count;
     return result;
 }
@@ -201,6 +201,11 @@ v2f32_t rn_measure_string(rn_font_t *font, s8_t string) {
     return rn_base_draw_string(font, string, v2f32(0,0), v4f32(0,0,0,0), false);
 }
 
+void rn_set_clip(r2f32_t rect) {
+    rn_cmd_t *cmd = rn_get_cmd(rn_cmd_kind_set_clip);
+    cmd->rect = rect;
+}
+
 void rn_init(ma_arena_t *perm, f32 _font_size) {
     rn_state.cap = 1024*256;
     rn_state.vertices = ma_push_array(perm, rn_vertex_t, rn_state.cap);
@@ -323,6 +328,12 @@ void rn_end(v2f32_t window_size, v4f32_t color) {
             GLint s_texture = 0; // texture unit that sampler2D will use in GLSL code
             glBindTextureUnit(s_texture, rn_state.main_font.texture_id);
             glDrawArrays(GL_TRIANGLES, 0, it->len);
+        } else if (it->kind == rn_cmd_kind_set_clip) {
+            GLint   x    = (GLint)it->rect.min.x;
+            GLint   y    = (GLint)it->rect.min.y;
+            GLsizei w    = (GLsizei)(it->rect.max.x - x);
+            GLsizei h    = (GLsizei)(it->rect.max.y - y);
+            glScissor(x, (GLint)window_size.y - (GLint)it->rect.max.y, w, h);
         } else_is_invalid;
     }
 

src/wasm_app/ui.c

@@ -373,6 +373,7 @@ fn void ui_draw(void) {
             rect_color = accent1_color_global;
         }
 
+        // rn_set_clip(box->parent->rect);
         if (is_flag_set(box->flags, ui_box_flag_draw_rect)) {
             rn_draw_rect(box->rect, rect_color);
         }