add fov support

It's needed in order to avoid conflicts with GLRage. Basically we
override the entire thing in a way that stays consistent with it. In the
future it might be a subject to improvements.

Tomb1Main.json

@@ -130,5 +130,15 @@
     // Fixes ability to obtain pistols by running out of ammo with other guns.
     // (Happens if you get to shotgun before obtaining pistols in Natla's
     // Mines)
-    "fix_illegal_gun_equip": true
+    "fix_illegal_gun_equip": true,
+
+    // The desired field of view in degrees, which overrides the hardcoded
+    // default. The default values are 80 (horizontal) and 65 (vertical).
+    "fov_value": 65,
+
+    // Interprets fov_value as vertical instead of horizontal field of view.
+    // May be advantageous for widescreen resolutions, especially for
+    // multi-screen setups, since it distorts the left and right side instead
+    // of cropping away the top and bottom part of the screen.
+    "fov_vertical": true,
 }

src/3dsystem/3d_gen.c

@@ -1,6 +1,12 @@
 #include "3dsystem/3d_gen.h"
 #include "3dsystem/phd_math.h"
 #include "game/vars.h"
+#include "config.h"
+
+#ifdef T1M_FEAT_UI
+    #include "specific/output.h"
+    #include <math.h>
+#endif
 
 void phd_InitWindow(
     int32_t x, int32_t y, int32_t width, int32_t height, int32_t nearz,
@@ -32,6 +38,19 @@ void phd_InitWindow(
 
 void AlterFOV(PHD_ANGLE fov)
 {
+#ifdef T1M_FEAT_UI
+    // NOTE: every caller GAME_FOV anyway, apart from GLRage which we override
+    // here.
+    fov = T1MConfig.fov_value * PHD_DEGREE;
+
+    if (T1MConfig.fov_vertical) {
+        double aspect_ratio = GetRenderWidth() / (double)GetRenderHeight();
+        double fov_rad_h = fov * M_PI / 32760;
+        double fov_rad_v = 2 * atan(aspect_ratio * tan(fov_rad_h / 2));
+        fov = round((fov_rad_v / M_PI) * 32760);
+    }
+#endif
+
     int16_t c = phd_cos(fov / 2);
     int16_t s = phd_sin(fov / 2);
     PhdPersp = (c * (PhdWinWidth / 2)) / s;

src/config.c

@@ -1,8 +1,9 @@
+#include "config.h"
+#include "game/const.h"
+#include "json_utils.h"
+#include "util.h"
 #include <stdio.h>
 #include <string.h>
-#include "json_utils.h"
-#include "config.h"
-#include "utils.h"
 
 #define Q(x) #x
 #define QUOTE(x) Q(x)
@@ -119,6 +120,7 @@ int T1MReadConfig()
     READ_BOOL(fix_pyramid_secret_trigger);
     READ_BOOL(fix_hardcoded_secret_counts);
     READ_BOOL(fix_illegal_gun_equip);
+    READ_BOOL(fov_vertical);
 
     T1MConfig.healthbar_showing_mode =
         ReadBarShowingMode(json, "healthbar_showing_mode");
@@ -139,6 +141,12 @@ int T1MReadConfig()
     T1MConfig.enemy_healthbar_color =
         ReadBarColorConfig(json, "enemy_healthbar_color", T1M_BC_GREY);
 
+    T1MConfig.fov_value = JSONGetIntegerValue(json, "fov_value");
+    if (!T1MConfig.fov_value) {
+        T1MConfig.fov_value = GAME_FOV;
+    }
+    CLAMP(T1MConfig.fov_value, 30, 255);
+
     free(json);
     free(cfg_data);
     return 1;

src/config.h

@@ -60,6 +60,8 @@ struct {
     int8_t fix_pyramid_secret_trigger;
     int8_t fix_hardcoded_secret_counts;
     int8_t fix_illegal_gun_equip;
+    int8_t fov_value;
+    int8_t fov_vertical;
 } T1MConfig;
 
 int T1MReadConfig();

src/json_utils.c

@@ -1,5 +1,6 @@
 #include "json_utils.h"
 #include <string.h>
+#include "util.h"
 
 struct json_value_s* JSONGetField(struct json_value_s* root, const char* name)
 {
@@ -27,6 +28,19 @@ int8_t JSONGetBooleanValue(struct json_value_s* root, const char* name)
     return field->type == json_type_true;
 }
 
+int32_t JSONGetIntegerValue(struct json_value_s* root, const char* name)
+{
+    struct json_value_s* field = JSONGetField(root, name);
+    if (!field) {
+        return 0;
+    }
+    struct json_number_s* number = json_value_as_number(field);
+    if (!number) {
+        return 0;
+    }
+    return atoi(number->number);
+}
+
 const char* JSONGetStringValue(struct json_value_s* root, const char* name)
 {
     struct json_value_s* field = JSONGetField(root, name);

src/json_utils.h

@@ -5,6 +5,7 @@
 
 struct json_value_s* JSONGetField(struct json_value_s* root, const char* name);
 int8_t JSONGetBooleanValue(struct json_value_s* root, const char* name);
+int32_t JSONGetIntegerValue(struct json_value_s* root, const char* name);
 const char* JSONGetStringValue(struct json_value_s* root, const char* name);
 
 #endif

src/util.h

@@ -13,6 +13,30 @@
 #define CHK_ALL(a, b) (((a) & (b)) == (b))
 #define CHK_ANY(a, b) (((a) & (b)) != 0)
 
+#define CLAMPL(a, b)                                                           \
+    do {                                                                       \
+        if ((a) < (b))                                                         \
+            (a) = (b);                                                         \
+    } while (0)
+#define CLAMPG(a, b)                                                           \
+    do {                                                                       \
+        if ((a) > (b))                                                         \
+            (a) = (b);                                                         \
+    } while (0)
+#define CLAMP(a, b, c)                                                         \
+    do {                                                                       \
+        if ((a) < (b))                                                         \
+            (a) = (b);                                                         \
+        else if ((a) > (c))                                                    \
+            (a) = (c);                                                         \
+    } while (0)
+#define SWAP(a, b, c)                                                          \
+    do {                                                                       \
+        (c) = (a);                                                             \
+        (a) = (b);                                                             \
+        (b) = (c);                                                             \
+    } while (0)
+
 #pragma pack(push, 1)
 typedef struct {
     uint8_t opcode; // must be 0xE9