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Add y_plane parameter to screen_to_world(), closes #245

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screen_to_world() previously only intersected the Y=0 plane.
Now accepts an optional y_plane parameter (default 0.0) for
intersecting arbitrary horizontal planes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
John McCardle 2026-02-07 20:15:48 -05:00
commit f766e9efa2
2 changed files with 65 additions and 10 deletions
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21
src/3d/Viewport3D.cpp
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@ -196,7 +196,7 @@ void Viewport3D::orbitCamera(float angle, float distance, float height) {
camera_.setTarget(vec3(0, 0, 0));
}
vec3 Viewport3D::screenToWorld(float screenX, float screenY) {
vec3 Viewport3D::screenToWorld(float screenX, float screenY, float yPlane) {
// Convert screen coordinates to normalized device coordinates (-1 to 1)
// screenX/Y are relative to the viewport position
float ndcX = (2.0f * screenX / size_.x) - 1.0f;
@ -217,10 +217,10 @@ vec3 Viewport3D::screenToWorld(float screenX, float screenY) {
vec3 rayDir = vec3(rayWorld4.x, rayWorld4.y, rayWorld4.z).normalized();
vec3 rayOrigin = camera_.getPosition();
// Intersect with Y=0 plane (ground level)
// Intersect with Y=yPlane horizontal plane
// This is a simplification - for hilly terrain, you'd want ray-marching
if (std::abs(rayDir.y) > 0.0001f) {
float t = -rayOrigin.y / rayDir.y;
float t = (yPlane - rayOrigin.y) / rayDir.y;
if (t > 0) {
return rayOrigin + rayDir * t;
}
@ -2453,16 +2453,16 @@ static PyObject* Viewport3D_billboard_count(PyViewport3DObject* self, PyObject*
// =============================================================================
static PyObject* Viewport3D_screen_to_world(PyViewport3DObject* self, PyObject* args, PyObject* kwds) {
static const char* kwlist[] = {"x", "y", NULL};
static const char* kwlist[] = {"x", "y", "y_plane", NULL};
float x = 0.0f, y = 0.0f;
float x = 0.0f, y = 0.0f, y_plane = 0.0f;
if (!PyArg_ParseTupleAndKeywords(args, kwds, "ff", const_cast<char**>(kwlist), &x, &y)) {
if (!PyArg_ParseTupleAndKeywords(args, kwds, "ff|f", const_cast<char**>(kwlist), &x, &y, &y_plane)) {
return NULL;
}
// Adjust for viewport position (user passes screen coords relative to viewport)
vec3 worldPos = self->data->screenToWorld(x, y);
vec3 worldPos = self->data->screenToWorld(x, y, y_plane);
// Return None if no intersection (ray parallel to ground or invalid)
if (worldPos.x < 0 && worldPos.y < 0 && worldPos.z < 0) {
@ -2833,13 +2833,14 @@ PyMethodDef Viewport3D_methods[] = {
// Camera & Input methods (Milestone 8)
{"screen_to_world", (PyCFunction)mcrf::Viewport3D_screen_to_world, METH_VARARGS | METH_KEYWORDS,
"screen_to_world(x, y) -> tuple or None\n\n"
"screen_to_world(x, y, y_plane=0.0) -> tuple or None\n\n"
"Convert screen coordinates to world position via ray casting.\n\n"
"Args:\n"
" x: Screen X coordinate relative to viewport\n"
" y: Screen Y coordinate relative to viewport\n\n"
" y: Screen Y coordinate relative to viewport\n"
" y_plane: Y value of horizontal plane to intersect (default: 0.0)\n\n"
"Returns:\n"
" (x, y, z) world position tuple, or None if no intersection with ground plane"},
" (x, y, z) world position tuple, or None if no intersection with the plane"},
{"follow", (PyCFunction)mcrf::Viewport3D_follow, METH_VARARGS | METH_KEYWORDS,
"follow(entity, distance=10, height=5, smoothing=1.0)\n\n"
"Position camera to follow an entity.\n\n"