Implementing the target camera
by William C. Y. Lo, Raymond C. H. Lo, David Wolff, Muhammad Mobeen Movania
OpenGL – Build high performance graphics
- OpenGL – Build high performance graphics
- Table of Contents
- OpenGL – Build high performance graphics
- OpenGL – Build high performance graphics
- Credits
- Preface
- 1. Module 1
- 1. Introduction to Modern OpenGL
- Introduction
- Setting up the OpenGL v3.3 core profile on Visual Studio 2010 using the GLEW and freeglut libraries
- Designing a GLSL shader class
- Rendering a simple colored triangle using shaders
- Doing a ripple mesh deformer using the vertex shader
- Dynamically subdividing a plane using the geometry shader
- Dynamically subdividing a plane using the geometry shader with instanced rendering
- Drawing a 2D image in a window using the fragment shader and the SOIL image loading library
- 2. 3D Viewing and Object Picking
- Introduction
- Implementing a vector-based camera with FPS style input support
- Implementing the free camera
- Implementing the target camera
- Implementing view frustum culling
- Implementing object picking using the depth buffer
- Implementing object picking using color
- Implementing object picking using scene intersection queries
- 3. Offscreen Rendering and Environment Mapping
- Introduction
- Implementing the twirl filter using the fragment shader
- Rendering a skybox using static cube mapping
- Implementing a mirror with render-to-texture using FBO
- Rendering a reflective object using dynamic cube mapping
- Implementing area filtering (sharpening/blurring/embossing) on an image using convolution
- Implementing the glow effect
- 4. Lights and Shadows
- Introduction
- Implementing per-vertex and per-fragment point lighting
- Implementing per-fragment directional light
- Implementing per-fragment point light with attenuation
- Implementing per-fragment spot light
- Implementing shadow mapping with FBO
- Implemeting shadow mapping with percentage closer filtering (PCF)
- Implementing variance shadow mapping
- 5. Mesh Model Formats and Particle Systems
- 6. GPU-based Alpha Blending and Global Illumination
- Introduction
- Implementing order-independent transparency using front-to-back peeling
- Implementing order-independent transparency using dual depth peeling
- Implementing screen space ambient occlusion (SSAO)
- Implementing global illumination using spherical harmonics lighting
- Implementing GPU-based ray tracing
- Implementing GPU-based path tracing
- 7. GPU-based Volume Rendering Techniques
- Introduction
- Implementing volume rendering using 3D texture slicing
- Implementing volume rendering using single-pass GPU ray casting
- Implementing pseudo-isosurface rendering in single-pass GPU ray casting
- Implementing volume rendering using splatting
- Implementing transfer function for volume classification
- Implementing polygonal isosurface extraction using the Marching Tetrahedra algorithm
- Implementing volumetric lighting using the half-angle slicing
- 8. Skeletal and Physically-based Simulation on the GPU
- Introduction
- Implementing skeletal animation using matrix palette skinning
- Implementing skeletal animation using dual quaternion skinning
- Modeling cloth using transform feedback
- Implementing collision detection and response on a transform feedback-based cloth model
- Implementing a particle system using transform feedback
- 1. Introduction to Modern OpenGL
- 2. Module 2
- 1. Getting Started with GLSL
- Introduction
- Using a function loader to access the latest OpenGL functionality
- Using GLM for mathematics
- Determining the GLSL and OpenGL version
- Compiling a shader
- Linking a shader program
- Sending data to a shader using vertex attributes and vertex buffer objects
- Getting a list of active vertex input attributes and locations
- Sending data to a shader using uniform variables
- Getting a list of active uniform variables
- Using uniform blocks and uniform buffer objects
- Getting debug messages
- Building a C++ shader program class
- 2. The Basics of GLSL Shaders
- Introduction
- Implementing diffuse, per-vertex shading with a single point light source
- Implementing per-vertex ambient, diffuse, and specular (ADS) shading
- Using functions in shaders
- Implementing two-sided shading
- Implementing flat shading
- Using subroutines to select shader functionality
- Discarding fragments to create a perforated look
- 3. Lighting, Shading, and Optimization
- 4. Using Textures
- 5. Image Processing and Screen Space Techniques
- 6. Using Geometry and Tessellation Shaders
- 7. Shadows
- 8. Using Noise in Shaders
- 9. Particle Systems and Animation
- 10. Using Compute Shaders
- 1. Getting Started with GLSL
- 3. Module 3
- 1. Getting Started with OpenGL
- Introduction
- Setting up a Windows-based development platform
- Setting up a Mac-based development platform
- Setting up a Linux-based development platform
- Installing the GLFW library in Windows
- Installing the GLFW library in Mac OS X and Linux
- Creating your first OpenGL application with GLFW
- Compiling and running your first OpenGL application in Windows
- Compiling and running your first OpenGL application in Mac OS X or Linux
- 2. OpenGL Primitives and 2D Data Visualization
- 3. Interactive 3D Data Visualization
- 4. Rendering 2D Images and Videos with Texture Mapping
- Introduction
- Getting started with modern OpenGL (3.2 or higher)
- Setting up the GLEW, GLM, SOIL, and OpenCV libraries in Windows
- Setting up the GLEW, GLM, SOIL, and OpenCV libraries in Mac OS X/Linux
- Creating your first vertex and fragment shader using GLSL
- Rendering 2D images with texture mapping
- Real-time video rendering with filters
- 5. Rendering of Point Cloud Data for 3D Range-sensing Cameras
- 6. Rendering Stereoscopic 3D Models using OpenGL
- 7. An Introduction to Real-time Graphics Rendering on a Mobile Platform using OpenGL ES 3.0
- 8. Interactive Real-time Data Visualization on Mobile Devices
- 9. Augmented Reality-based Visualization on Mobile or Wearable Platforms
- A. Bibliography
- 1. Getting Started with OpenGL
- Index
The target camera works the opposite way. Rather than the position, the target remains fixed, while the camera moves or rotates around the target. Some operations like panning, move both the target and the camera position together.
The following figure shows an illustration of a target camera. Note that the small box is the target position for the camera.
The code for this recipe resides in the Chapter2/TargetCamera directory. The CTargetCamera class is defined in the Chapter2/src/TargetCamera.[h/cpp] files. The class declaration is as follows:
class CTargetCamera : public CAbstractCamera
{
public:
CTargetCamera(void);
~CTargetCamera(void);
void Update();
void Rotate(const float yaw, const float pitch, const float roll);
void SetTarget(const glm::vec3 tgt);
const glm::vec3 GetTarget() const;
void Pan(const float dx, const float dy);
void Zoom(const float amount );
void Move(const float dx, const float dz);
protected:
glm::vec3 target;
float minRy, maxRy;
float distance;
float minDistance, maxDistance;
};We implement the target camera as follows:
- Define the
CTargetCameraclass with a target position (target), the rotation limits (minRyandmaxRy), the distance between the target and the camera position (distance), and the distance limits (minDistanceandmaxDistance). - In the
Updatemethod, calculate the new orientation (rotation) matrix using the current camera orientations (that is, yaw, pitch, and roll amount):glm::mat4 R = glm::yawPitchRoll(yaw,pitch,roll);
- Use the distance to get a vector and then translate this vector by the current rotation matrix:
glm::vec3 T = glm::vec3(0,0,distance); T = glm::vec3(R*glm::vec4(T,0.0f));
- Get the new camera position by adding the translation vector to the target position:
position = target + T;
- Recalculate the orthonormal basis and then the view matrix:
look = glm::normalize(target-position); up = glm::vec3(R*glm::vec4(UP,0.0f)); right = glm::cross(look, up); V = glm::lookAt(position, target, up);
The Move function moves both the position and target by the same amount in both look and right vector directions.
void CTargetCamera::Move(const float dx, const float dy) {
glm::vec3 X = right*dx;
glm::vec3 Y = look*dy;
position += X + Y;
target += X + Y;
Update();
}The Pan function moves in the xy plane only, hence the up vector is used instead of the look vector:
void CTargetCamera::Pan(const float dx, const float dy) {
glm::vec3 X = right*dx;
glm::vec3 Y = up*dy;
position += X + Y;
target += X + Y;
Update();
}The Zoom function moves the position in the look direction:
void CTargetCamera::Zoom(const float amount) {
position += look * amount;
distance = glm::distance(position, target);
Distance = std::max(minDistance, std::min(distance, maxDistance));
Update();
}The demonstration for this recipe renders an infinite checkered plane, as in the previous recipe, and is shown in the following figure:
- DHPOWare OpenGL camera demo – Part 1 (http://www.dhpoware.com/demos/glCamera1.html)
- DHPOWare OpenGL camera demo – Part 2 (http://www.dhpoware.com/demos/glCamera2.html)
- DHPOWare OpenGL camera demo – Part 3 (http://www.dhpoware.com/demos/glCamera3.html)
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