Orthographic and perspective camera projections.

src/Camera.cpp

@@ -18,6 +18,41 @@
 namespace Magnum {
 
 Camera::Camera(AbstractObject* parent): AbstractObject(parent), viewportWidth(0), viewportHeight(0), _aspectRatioPolicy(Extend) {
+    setOrthographic(2, 1, 1000);
+}
+
+void Camera::setOrthographic(GLfloat size, GLfloat near, GLfloat far) {
+    /* Scale the volume down so it fits in (-1, 1) in all directions */
+    GLfloat xyScale = 2/size;
+    GLfloat zScale = 2/(far-near);
+    rawProjectionMatrix = Matrix4::scaling(xyScale, xyScale, -zScale);
+
+    /* Move the volume on z into (-1, 1) range */
+    rawProjectionMatrix = Matrix4::translation(0, 0, -1-near*zScale)*rawProjectionMatrix;
+
+    fixAspectRatio();
+}
+
+void Camera::setPerspective(GLfloat fov, GLfloat near, GLfloat far) {
+    /* First move the volume on z in (-1, 1) range */
+    rawProjectionMatrix = Matrix4::translation(0, 0, 2*far*near/(far+near));
+
+    /* Then apply magic perspective matrix (with reversed Z) */
+    static GLfloat a[] = {  1, 0,  0,  0,
+                            0, 1,  0,  0,
+                            0, 0,  -1,  -1,
+                            0, 0,  0,  0  };
+    rawProjectionMatrix = Matrix4(a)*rawProjectionMatrix;
+
+    /* Then scale the volume down so it fits in (-1, 1) in all directions */
+    GLfloat xyScale = 1/tan(fov/2);
+    GLfloat zScale = 1+2*near/(far-near);
+    rawProjectionMatrix = Matrix4::scaling(xyScale, xyScale, zScale)*rawProjectionMatrix;
+
+    /* And... another magic */
+    rawProjectionMatrix.set(3, 3, 0);
+
+    fixAspectRatio();
 }
 
 Matrix4 Camera::cameraMatrix() const {

src/Camera.h

@@ -40,6 +40,8 @@ class Camera: public AbstractObject {
         /**
          * @brief Constructor
          * @param parent        Parent object
+         *
+         * Calls <tt>setOrthographic(2, 1, 1000)</tt>.
          */
         Camera(AbstractObject* parent = 0);
 
@@ -49,6 +51,25 @@ class Camera: public AbstractObject {
         /** @brief Set aspect ratio policy */
         void setAspectRatioPolicy(AspectRatioPolicy policy) { _aspectRatioPolicy = policy; }
 
+        /**
+         * @brief Set orthographic projection
+         * @param size      Size of (square) view
+         * @param near      Near clipping plane
+         * @param far       Far clipping plane
+         *
+         * The volume of given size will be scaled down to range (-1, 1) on all
+         * directions.
+         */
+        void setOrthographic(GLfloat size, GLfloat near, GLfloat far);
+
+        /**
+         * @brief Set perspective projection
+         * @param fov       Field of view angle
+         * @param near      Near clipping plane
+         * @param far       Far clipping plane
+         */
+        void setPerspective(GLfloat fov, GLfloat near, GLfloat far);
+
         /**
          * @brief Camera matrix
          *

src/Test/CMakeLists.txt

@@ -1 +1,2 @@
 magnum_add_test(AbstractObjectTest AbstractObjectTest.h AbstractObjectTest.cpp Magnum)
+magnum_add_test(CameraTest CameraTest.h CameraTest.cpp Magnum)

src/Test/CameraTest.cpp

@@ -0,0 +1,53 @@
+/*
+    Copyright © 2010 Vladimír Vondruš <mosra@centrum.cz>
+
+    This file is part of Magnum.
+
+    Magnum is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License version 3
+    only, as published by the Free Software Foundation.
+
+    Magnum is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU Lesser General Public License version 3 for more details.
+*/
+
+#include "CameraTest.h"
+#include "Camera.h"
+
+#include <QtTest/QTest>
+
+QTEST_APPLESS_MAIN(Magnum::Test::CameraTest)
+
+namespace Magnum { namespace Test {
+
+void CameraTest::orthographic() {
+    Camera camera;
+    camera.setOrthographic(5, 1, 9);
+
+    GLfloat a[] = {
+        0.4f,   0,      0,          0,
+        0,      0.4f,   0,          0,
+        0,      0,      -0.25f,    0,
+        0,      0,      -1.25f,     1
+    };
+
+    QVERIFY(camera.projectionMatrix() == a);
+}
+
+void CameraTest::perspective() {
+    Camera camera;
+    camera.setPerspective(27*PI/180, 32.0f, 100);
+
+    GLfloat a[] = {
+        4.1652994f, 0,          0,           0,
+        0,          4.1652994f, 0,           0,
+        0,          0,         -1.9411764f, -1,
+        0,          0,         -94.1176452f, 0
+    };
+
+    QVERIFY(camera.projectionMatrix() == Matrix4(a));
+}
+
+}}

src/Test/CameraTest.h

@@ -0,0 +1,32 @@
+#ifndef Magnum_CameraTest_h
+#define Magnum_CameraTest_h
+/*
+    Copyright © 2010 Vladimír Vondruš <mosra@centrum.cz>
+
+    This file is part of Magnum.
+
+    Magnum is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License version 3
+    only, as published by the Free Software Foundation.
+
+    Magnum is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+    GNU Lesser General Public License version 3 for more details.
+*/
+
+#include <QtCore/QObject>
+
+namespace Magnum { namespace Test {
+
+class CameraTest: public QObject {
+    Q_OBJECT
+
+    private slots:
+        void orthographic();
+        void perspective();
+};
+
+}}
+
+#endif