orthographic projection for fov=0, rework of order and defaults for 3d camera api

include/twn_draw.h

@@ -79,7 +79,11 @@ TWN_API void draw_billboard(const char *texture,
                             bool cylindrical);  /* optional, default: false */
 
 /* sets a perspective 3d camera to be used for all 3d commands */
-TWN_API void draw_camera(Vec3 position, float fov, Vec3 up, Vec3 direction);
+/* fov = 0 corresponds to orthographic projection */
+TWN_API void draw_camera(Vec3 position,
+                         Vec3 direction,        /* optional, default: (0, 0, -1) */
+                         Vec3 up,               /* optional, default: (0, 1, 0) */
+                         float fov);            /* optional, default: PI / 6 * 3 (90 degrees) */
 
 /* same as draw_camera(), but with first person controller in mind */
 /* direction and up vectors are inferred from roll, pitch and yaw parameters (in radians) */
@@ -88,11 +92,12 @@ typedef struct DrawCameraFromPrincipalAxesResult {
     Vec3 direction;
     Vec3 up;
 } DrawCameraFromPrincipalAxesResult;
-TWN_API DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 position,
+TWN_API DrawCameraFromPrincipalAxesResult
-                                                                          float fov,
+draw_camera_from_principal_axes(Vec3 position,
-                                                                          float roll,
+                                float roll,   /* optional, default: 0 */
-                                                                          float pitch,
+                                float pitch,  /* optional, default: 0 */
-                                                                          float yaw);
+                                float yaw,    /* optional, default: 0 */
+                                float fov);   /* optional, default: PI / 6 * 3 (90 degrees) */
 
 /* expects '*' masks that will be expanded to 6 names: 'up', 'down', 'east', 'west', 'north' and 'south' */
 TWN_API void draw_skybox(const char *textures);

share/twn_api.json

@@ -179,9 +179,9 @@
             "header": "twn_draw.h",
             "params": [
                 { "name": "position", "type": "Vec3" },
-                { "name": "fov", "type": "float" },
+                { "name": "direction", "type": "Vec3", "default": { "x": 0, "y": 0, "z": -1 } },
-                { "name": "up", "type": "Vec3" },
+                { "name": "up", "type": "Vec3", "default": { "x": 0, "y": 1, "z": 0 } },
-                { "name": "direction", "type": "Vec3" }
+                { "name": "fov", "type": "float", "default": 1.57079632679 }
             ]
         },
 
@@ -191,10 +191,10 @@
             "header": "twn_draw.h",
             "params": [
                 { "name": "position", "type": "Vec3" },
-                { "name": "fov", "type": "float" },
+                { "name": "roll", "type": "float", "default": 0 },
-                { "name": "roll", "type": "float" },
+                { "name": "pitch", "type": "float", "default": 0 },
-                { "name": "pitch", "type": "float" },
+                { "name": "yaw", "type": "float", "default": 0 },
-                { "name": "yaw", "type": "float" }
+                { "name": "fov", "type": "float", "default": 1.57079632679 }
             ],
             "return": {
                 "fields": [

src/rendering/twn_draw.c

@@ -413,8 +413,9 @@ void render(void) {
 }
 
 
-void draw_camera(Vec3 position, float fov, Vec3 up, Vec3 direction) {
+void draw_camera(Vec3 position, Vec3 direction, Vec3 up, float fov) {
-    if (fabsf(0.0f - fov) < 0.00001f || fov >= M_PIf)
+    bool const orthographic = fabsf(0.0f - fov) < 0.00001f;
+    if (!orthographic && fov >= M_PIf)
         log_warn("Invalid fov given (%f)", (double)fov);
 
     Camera const camera = {
@@ -424,14 +425,24 @@ void draw_camera(Vec3 position, float fov, Vec3 up, Vec3 direction) {
         .up = up,
     };
 
-    camera_projection_matrix = camera_perspective(&camera);
+    if (!orthographic)
-    camera_look_at_matrix    = camera_look_at(&camera);
+        camera_projection_matrix = camera_perspective(&camera);
+    else
+        camera_projection_matrix = camera_orthographic(&camera);
+
+    camera_look_at_matrix = camera_look_at(&camera);
 }
 
 
 /* TODO: https://stackoverflow.com/questions/62493770/how-to-add-roll-in-camera-class */
-DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 position, float fov, float roll, float pitch, float yaw) {
+DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 position,
-    if (fabsf(0.0f - fov) < 0.00001f || fov >= M_PIf)
+                                                                  float roll,
+                                                                  float pitch,
+                                                                  float yaw,
+                                                                  float fov)
+{
+    bool const orthographic = fabsf(0.0f - fov) < 0.00001f;
+    if (!orthographic && fov >= M_PIf)
         log_warn("Invalid fov given (%f)", (double)fov);
 
     (void)roll;
@@ -451,8 +462,12 @@ DrawCameraFromPrincipalAxesResult draw_camera_from_principal_axes(Vec3 position,
         .up = (Vec3){0, 1, 0},
     };
 
-    camera_projection_matrix = camera_perspective(&camera);
+    if (!orthographic)
-    camera_look_at_matrix    = camera_look_at(&camera);
+        camera_projection_matrix = camera_perspective(&camera);
+    else
+        camera_projection_matrix = camera_orthographic(&camera);
+
+    camera_look_at_matrix = camera_look_at(&camera);
 
     return (DrawCameraFromPrincipalAxesResult) {
         .direction = camera.target,

src/twn_camera.c

@@ -52,3 +52,24 @@ Matrix4 camera_perspective(const Camera *const camera) {
 
     return result;
 }
+
+Matrix4 camera_orthographic(const Camera *const camera) {
+    /* from cglm */
+    (void)camera;
+
+    Matrix4 result = {0};
+
+    const float rl =  1.0f / (float)1;
+    const float tb =  1.0f / (float)1;
+    const float fn = -1.0f / (CAMERA_FAR_Z - CAMERA_NEAR_Z);
+
+    result.row[0].x =  2.0f * rl;
+    result.row[1].y =  2.0f * tb;
+    result.row[2].z =  2.0f * fn;
+    result.row[3].x = -(float)1   * rl;
+    result.row[3].y = -(float)1  * tb;
+    result.row[3].z =  (CAMERA_FAR_Z + CAMERA_NEAR_Z) * fn;
+    result.row[3].w =  1.0f;
+
+    return result;
+}

src/twn_camera_c.h

@@ -16,7 +16,7 @@ typedef struct Camera {
 } Camera;
 
 Matrix4 camera_look_at(const Camera *camera);
-
 Matrix4 camera_perspective(const Camera *const camera);
+Matrix4 camera_orthographic(const Camera *const camera);
 
 #endif