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SG_CAMERA(3) Library Functions Manual SG_CAMERA(3) NAME SG_Camera -- Agar-SG camera node SYNOPSIS #include <agar/core.h> #include <agar/sg.h> DESCRIPTION A SG_Camera node defines a point of view inside a SG(3) scene-graph. When rendering a scene, the SG_View(3) widget is associated with a SG_Camera node, which defines both the projection matrix and the ini- tial OpenGL modelview matrix. The SG_Camera class implements perspective, orthographic and user-spec- ified projection modes. INHERITANCE HIERARCHY AG_Object(3) -> SG_Node(3) -> SG_Camera. INITIALIZATION SG_Camera * SG_CameraNew(SG_Node *parent, const char *name) SG_Camera * SG_CameraNewDuplicate(SG_Node *parent, const char *name, const SG_Camera *origCam) The SG_CameraNew() function allocates, initializes, and attaches a new SG_Camera object. The SG_CameraNewDuplicate() variant initializes the new camera with the same parameters as camOrig. PROJECTION TRANSFORMATIONS Projection transformations are used to map object coordinates to window coordinates for two-dimensional display devices. Each SG_Camera in- stance is associated with a projection transformation. void SG_CameraGetProjection(SG_Camera *cam, M_Matrix44 *P) void SG_CameraSetOrthographic(SG_Camera *cam) void SG_CameraSetPerspective(SG_Camera *cam, M_Real fov, M_Real aspect) void SG_CameraSetUser(SG_Camera *cam, const M_Matrix44 *Pleft, const M_Matrix44 *Pright) void SG_CameraSetClipPlanes(SG_Camera *cam, M_Real near, M_Real far) void SG_CameraSetBackPolyMode(SG_Camera *cam, const SG_CameraPolyMode *polymode) void SG_CameraSetFacePolyMode(SG_Camera *cam, const SG_CameraPolyMode *polymode) The SG_CameraGetProjection() function returns the current projection matrix of cam into P. The SG_CameraSetOrthographic() function sets the projection matrix of cam to an orthographic projection matrix. SG_CameraSetPerspective() selects a perspective matrix. For perspective projections, aspect de- fines the aspect ratio (ratio of width to height) and fov defines the field-of-view angle in degrees in the y direction. The SG_CameraSetUser() function sets the projection matrix of cam to user-specified matrices Pleft (left eye) and Pright (right eye). Un- less stereo rendering is activated, only Pleft is used. The near and far clipping planes are defined by SG_CameraSetClipPlanes(). near and far represent the distance from the standard XY plane to the near and far clipping planes. SG_CameraSetBackPolyMode() and SG_CameraSetFacePolyMode() configure the way back-facing or front-facing polygons are rendered by views using this camera. The structure is defined as: typedef struct sg_camera_polymode { enum { SG_CAMERA_POINTS, /* Render as points */ SG_CAMERA_WIREFRAME, /* Render in wireframe */ SG_CAMERA_FLAT_SHADED, /* Flat-shaded */ SG_CAMERA_SMOOTH_SHADED /* Smooth-shaded */ } mode; int cull; /* Cull entirely */ } SG_CameraPolyMode; CONTROLLING CAMERA ORIENTATION void SG_CameraRotMouse(SG_Camera *cam, SG_View *sv, int xRel, int yRel) void SG_CameraSetRotCtrlCircular(SG_Camera *cam, SG_Node *n) void SG_CameraSetRotCtrlElliptic(SG_Camera *cam, SG_Node *n1, SG_Node *n2) SG_CameraRotMouse() is typically invoked by SG_View(3) (or a derived widget) to rotate the camera by mouse action. xRel and yRel are the relative mouse coordinates since the last mouse motion event. SG_CameraSetRotCtrlCircular() configures the camera such that mouse mo- tion will translate to a circular orbit around a specified node n. Similarly, SG_CameraSetRotCtrlElliptic() arranges for an elliptic orbit around two specified nodes n1 and n2. INTERNAL WIDGET API void SG_CameraProject(SG_Camera *cam) void SG_CameraProjectLeft(SG_Camera *cam) void SG_CameraProjectRight(SG_Camera *cam) void SG_CameraSetup(SG_Camera *cam) The SG_CameraProject() function multiplies the current projection ma- trix by the projection matrix associated with a camera cam. If quad- buffer stereo project is needed, SG_CameraProjectLeft() and SG_CameraProjectRight() may be called instead. Functions are used in- ternally by SG_View(3), or derivatives of it. The camera object must be locked by the caller. The SG_CameraSetup() function applies the viewing transformation asso- ciated with a camera. As opposed to SG_CameraProject() which is only called on rescale, SG_CameraSetup() is normally called from the "draw" function of SG_View(3) (or derived widget), prior to rendering the scene. The camera object must be locked by the caller. STRUCTURE DATA For the SG_Camera object: enum sg_camera_pmode pmode Effective projection mode, one of SG_CAMERA_PERSPECTIVE, SG_CAMERA_ORTHOGRAPHIC or SG_CAMERA_USER_PROJ (read-only, use SG_CameraSetPerspective(), SG_CameraSetOrthographic() or SG_CameraSetUser() to set the projection mode). SG_CameraPolyMode polyFace Method of rendering for front-facing poly- gons (read-only, use SG_CameraSetFacePolyMode() to set). SG_CameraPolyMode polyBack Method of rendering for back-facing poly- gons (read-only, use SG_CameraSetBackPolyMode() to set). M_Real fov Field of view (in radians). M_Real aspect Aspect ratio. M_Real near Near clipping plane. M_Real far Far clipping plane. M_Matrix44 userProj User-specified projection matrix, usually given by SG_CameraSetUser(). The matrix is in column-major format. SEE ALSO M_Matrix(3), M_Real(3), M_Vector(3), SG(3), SG_Intro(3), SG_Light(3), SG_Node(3), SG_View(3) HISTORY The SG_Camera node class first appeared in Agar 1.6.0. Agar 1.7 December 21, 2022 SG_CAMERA(3)
NAME | SYNOPSIS | DESCRIPTION | INHERITANCE HIERARCHY | INITIALIZATION | PROJECTION TRANSFORMATIONS | CONTROLLING CAMERA ORIENTATION | INTERNAL WIDGET API | STRUCTURE DATA | SEE ALSO | HISTORY
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