sm64/enhancements/debug_box.patch

diff --git a/src/game/area.c b/src/game/area.c
index af9d0156..c68a7f6e 100644
--- a/src/game/area.c
+++ b/src/game/area.c
@@ -22,6 +22,7 @@
 #include "save_file.h"
 #include "level_table.h"
 #include "dialog_ids.h"
+#include "debug_box.h"
 
 struct SpawnInfo gPlayerSpawnInfos[1];
 struct GraphNode *D_8033A160[0x100];
@@ -363,6 +364,8 @@ void render_game(void) {
     if (gCurrentArea != NULL && !gWarpTransition.pauseRendering) {
         geo_process_root(gCurrentArea->unk04, D_8032CE74, D_8032CE78, gFBSetColor);
 
+        render_debug_boxes();
+
         gSPViewport(gDisplayListHead++, VIRTUAL_TO_PHYSICAL(&D_8032CF00));
 
         gDPSetScissor(gDisplayListHead++, G_SC_NON_INTERLACE, 0, BORDER_HEIGHT, SCREEN_WIDTH,
diff --git a/src/game/debug_box.c b/src/game/debug_box.c
new file mode 100644
index 00000000..1ffe0288
--- /dev/null
+++ b/src/game/debug_box.c
@@ -0,0 +1,281 @@
+#include <ultra64.h>
+
+#include "sm64.h"
+#include "game/game_init.h"
+#include "game/geo_misc.h"
+#include "engine/math_util.h"
+
+#include "debug_box.h"
+
+/**
+ * @file debug_box.c
+ * Draws 3D boxes for debugging purposes.
+ *
+ * How to use:
+ *
+ * In render_game() in area.c, add a call to render_debug_boxes():
+ *
+ * void render_game(void) {
+ *    if (gCurrentArea != NULL && !gWarpTransition.pauseRendering) {
+ *        geo_process_root(...);
+ *
+ *        render_debug_boxes(); // add here
+ *
+ *        gSPViewport(...);
+ *        gDPSetScissor(...);
+ *    //...
+ *
+ * Now just call debug_box() whenever you want to draw one!
+ *
+ * debug_box by default takes two arguments: a center and bounds vec3f.
+ * This will draw a box starting from the point (center - bounds) to (center + bounds).
+ *
+ * Use debug_box_rot to draw a box rotated in the xz-plane.
+ *
+ * If you want to draw a box by specifying min and max points, use debug_box_pos() instead.
+ */
+
+/**
+ * Internal struct containing box info
+ */
+struct DebugBox {
+    u32 color;
+    Vec3s center;
+    Vec3s bounds;
+    s16 yaw;
+};
+
+struct DebugBox sBoxes[MAX_DEBUG_BOXES];
+s16 sNumBoxes = 0;
+
+extern Mat4 gMatStack[32]; //XXX: Hack
+
+/**
+ * The debug boxes' default transparency
+ */
+#define DBG_BOX_ALPHA     0x7F
+/**
+ * The debug boxes' default color. sCurBoxColor is reset to this every frame.
+ */
+#define DBG_BOX_DEF_COLOR 0xFF0000
+
+/**
+ * The color that new boxes will be drawn with.
+ */
+u32 sCurBoxColor = DBG_BOX_ALPHA << 24 | DBG_BOX_DEF_COLOR;
+
+/**
+ * The allocated size of a rotated box's dl
+ */
+#define DBG_BOX_ROT_DLSIZE ((s32)(6 * sizeof(Gfx) + 8 * sizeof(Vtx)))
+/**
+ * The allocated size of a normal box's dl
+ */
+#define DBG_BOX_DLSIZE     ((s32)(2 * sizeof(Gfx) + 8 * sizeof(Vtx)))
+
+/**
+ * Sets up the RCP for drawing the boxes
+ */
+static const Gfx dl_debug_box_begin[] = {
+    gsDPPipeSync(),
+#if DBG_BOX_ALPHA < 0xFF
+    gsDPSetRenderMode(G_RM_ZB_XLU_SURF, G_RM_NOOP2),
+#else
+    gsDPSetRenderMode(G_RM_ZB_OPA_SURF, G_RM_NOOP2),
+#endif
+    gsSPClearGeometryMode(G_LIGHTING | G_CULL_BACK),
+    gsSPSetGeometryMode(G_ZBUFFER | G_SHADE | G_SHADING_SMOOTH),
+    gsSPTexture(0, 0, 0, 0, G_OFF),
+    gsDPSetCombineMode(G_CC_SHADE, G_CC_SHADE),
+    gsSPEndDisplayList(),
+};
+
+/**
+ * Actually draws the box
+ */
+static const Gfx dl_debug_draw_box[] = {
+    gsSP2Triangles(5,  4,  6, 0x0,  5,  6,  7, 0x0), // front
+    gsSP2Triangles(0,  1,  2, 0x0,  2,  1,  3, 0x0), // back
+
+    gsSP2Triangles(4,  0,  2, 0x0,  2,  6,  4, 0x0), // left
+    gsSP2Triangles(1,  5,  3, 0x0,  3,  5,  7, 0x0), // right
+
+    gsSP2Triangles(1,  0,  4, 0x0,  1,  4,  5, 0x0), // top
+    gsSP2Triangles(2,  3,  6, 0x0,  6,  3,  7, 0x0), // bottom
+
+    gsSPEndDisplayList(),
+};
+
+/**
+ * Adds a box to the list to be rendered this frame.
+ *
+ * If there are already MAX_DEBUG_BOXES boxes, does nothing.
+ */
+static void append_debug_box(Vec3f center, Vec3f bounds, s16 yaw)
+{
+    if (sNumBoxes >= MAX_DEBUG_BOXES) {
+        return;
+    }
+
+    vec3f_to_vec3s(sBoxes[sNumBoxes].center, center);
+    vec3f_to_vec3s(sBoxes[sNumBoxes].bounds, bounds);
+
+    sBoxes[sNumBoxes].yaw = yaw;
+    sBoxes[sNumBoxes].color = sCurBoxColor;
+
+    ++sNumBoxes;
+}
+
+/**
+ * Draw new boxes with the given color.
+ * Color format is 32-bit ARGB.
+ * If the alpha component is zero, DBG_BOX_ALPHA (0x7f) will be used instead.
+ * Ex: 0xFF0000 becomes 0x7FFF0000
+ */
+void debug_box_color(u32 color)
+{
+    if ((color >> 24) == 0) color |= (DBG_BOX_ALPHA << 24);
+    sCurBoxColor = color;
+}
+
+/**
+ * Draws a debug box from (center - bounds) to (center + bounds)
+ * To draw a rotated box, use debug_box_rot()
+ *
+ * @see debug_box_rot()
+ */
+void debug_box(Vec3f center, Vec3f bounds)
+{
+    append_debug_box(center, bounds, 0);
+}
+
+/**
+ * Draws a debug box from (center - bounds) to (center + bounds), rotating it by `yaw`
+ */
+void debug_box_rot(Vec3f center, Vec3f bounds, s16 yaw)
+{
+    append_debug_box(center, bounds, yaw);
+}
+
+/**
+ * Draws a debug box from pMin to pMax
+ * To draw a rotated box this way, use debug_box_pos_rot()
+ *
+ * @see debug_box_pos_rot()
+ */
+void debug_box_pos(Vec3f pMin, Vec3f pMax)
+{
+    debug_box_pos_rot(pMin, pMax, 0);
+}
+
+/**
+ * Draws a debug box from pMin to pMax, rotating it in the xz-plane by `yaw`
+ */
+void debug_box_pos_rot(Vec3f pMin, Vec3f pMax, s16 yaw)
+{
+    Vec3f center, bounds;
+
+    bounds[0] = (pMax[0] - pMin[0]) / 2.0f;
+    bounds[1] = (pMax[1] - pMin[1]) / 2.0f;
+    bounds[2] = (pMax[2] - pMin[2]) / 2.0f;
+
+    center[0] = pMin[0] + bounds[0];
+    center[1] = pMin[1] + bounds[1];
+    center[2] = pMin[2] + bounds[2];
+
+    append_debug_box(center, bounds, yaw);
+}
+
+static void render_box(int index)
+{
+    Vtx *verts;
+    Mtx *translate;
+    Mtx *rotate;
+    Mtx *translateback;
+    struct DebugBox *box = &sBoxes[index];
+    u32 color = box->color;
+
+    s32 x0 = box->center[0],
+        y0 = box->center[1],
+        z0 = box->center[2];
+
+    s32 xb = box->bounds[0],
+        yb = box->bounds[1],
+        zb = box->bounds[2];
+
+    if (box->yaw != 0 && (Gfx*)gGfxPoolEnd - gDisplayListHead < DBG_BOX_ROT_DLSIZE)
+        return;
+    else if ((Gfx*)gGfxPoolEnd - gDisplayListHead < DBG_BOX_DLSIZE)
+        return;
+
+    verts = alloc_display_list(8 * sizeof(Vtx));
+
+    if (verts != NULL) {
+        if (box->yaw != 0) {
+            // Translate to the origin, rotate, then translate back, effectively rotating the box about
+            // its center
+            translate =     alloc_display_list(sizeof(Mtx));
+            rotate =        alloc_display_list(sizeof(Mtx));
+            translateback = alloc_display_list(sizeof(Mtx));
+
+            guTranslate(translate, box->center[0],  box->center[1],  box->center[2]);
+            guRotate(rotate, box->yaw / (float)0x10000 * 360.0f, 0, 1.0f, 0);
+            guTranslate(translateback, -box->center[0], -box->center[1], -box->center[2]);
+
+            gSPMatrix(gDisplayListHead++, translate,     G_MTX_MODELVIEW | G_MTX_MUL | G_MTX_PUSH);
+            gSPMatrix(gDisplayListHead++, rotate,        G_MTX_MODELVIEW | G_MTX_MUL | G_MTX_NOPUSH);
+            gSPMatrix(gDisplayListHead++, translateback, G_MTX_MODELVIEW | G_MTX_MUL | G_MTX_NOPUSH);
+        }
+
+#define DBG_BOX_COL /**/ (color >> 16) & 0xff, (color >> 8) & 0xff, color & 0xff, (color >> 24) & 0xff
+#define DBG_BOX_VTX(i, x, y, z) make_vertex(verts, i, x, y, z, 0, 0, DBG_BOX_COL)
+        DBG_BOX_VTX(0, x0 - xb, y0 + yb, z0 - zb);
+        DBG_BOX_VTX(1, x0 + xb, y0 + yb, z0 - zb);
+        DBG_BOX_VTX(2, x0 - xb, y0 - yb, z0 - zb);
+        DBG_BOX_VTX(3, x0 + xb, y0 - yb, z0 - zb);
+        DBG_BOX_VTX(4, x0 - xb, y0 + yb, z0 + zb);
+        DBG_BOX_VTX(5, x0 + xb, y0 + yb, z0 + zb);
+        DBG_BOX_VTX(6, x0 - xb, y0 - yb, z0 + zb);
+        DBG_BOX_VTX(7, x0 + xb, y0 - yb, z0 + zb);
+#undef DBG_BOX_VTX
+
+        gSPVertex(gDisplayListHead++, VIRTUAL_TO_PHYSICAL(verts), 8, 0);
+
+        gSPDisplayList(gDisplayListHead++, dl_debug_draw_box);
+
+        if (box->yaw != 0) {
+            gSPPopMatrix(gDisplayListHead++, G_MTX_MODELVIEW);
+        }
+    }
+}
+
+void render_debug_boxes(void)
+{
+    s32 i;
+    Mtx *mtx;
+
+    debug_box_color(DBG_BOX_DEF_COLOR);
+
+    if (sNumBoxes == 0) {
+        return;
+    }
+
+    mtx = alloc_display_list(sizeof(Mtx));
+    // Don't draw if there isn't space for the configuration + at least one box
+    if (mtx == NULL || ((Gfx*)gGfxPoolEnd - gDisplayListHead) <= (s32)(2 * sizeof(Gfx)) + DBG_BOX_DLSIZE) {
+        sNumBoxes = 0;
+        return;
+    }
+
+    //XXX: This is hacky. Ths camera's look-at matrix is stored in gMatStack[1], so this is a simple way
+    //     of using it without reconstructing the matrix.
+    mtxf_to_mtx(mtx, gMatStack[1]);
+    gSPMatrix(gDisplayListHead++, mtx, G_MTX_MODELVIEW | G_MTX_LOAD | G_MTX_NOPUSH);
+    gSPDisplayList(gDisplayListHead++, dl_debug_box_begin);
+
+    for (i = 0; i < sNumBoxes; ++i) {
+        render_box(i);
+    }
+
+    sNumBoxes = 0;
+}
diff --git a/src/game/debug_box.h b/src/game/debug_box.h
new file mode 100644
index 00000000..540c85e4
--- /dev/null
+++ b/src/game/debug_box.h
@@ -0,0 +1,26 @@
+#ifndef DEBUG_BOX_H
+#define DEBUG_BOX_H
+
+/**
+ * @file debug_box.h
+ * Draws debug boxes, see debug_box.c for details
+ */
+
+#include "types.h"
+
+/**
+ * The max amount of debug boxes before debug_box() just returns.
+ * You can set this to something higher, but you might run out of space in the gfx pool.
+ */
+#define MAX_DEBUG_BOXES 512
+
+void debug_box_color(u32 color);
+void debug_box(Vec3f center, Vec3f bounds);
+void debug_box_rot(Vec3f center, Vec3f bounds, s16 yaw);
+
+void debug_box_pos(Vec3f pMin, Vec3f pMax);
+void debug_box_pos_rot(Vec3f pMin, Vec3f pMax, s16 yaw);
+
+void render_debug_boxes(void);
+
+#endif /* DEBUG_BOX_H */