Updated manual

This commit is contained in:
Christophe Riccio 2016-11-01 12:56:37 +01:00
parent 3ca24a12a1
commit c583fe0257

165
manual.md
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@ -155,38 +155,26 @@ To further help compilation time, GLM 0.9.5 introduced
```cpp
// Include GLM core features
\#include <glm/vec3.hpp>
\#include <glm/vec4.hpp>
\#include <glm/mat4x4.hpp>
\#include <glm/trigonometric.hpp>
#include <glm/vec3.hpp>
#include <glm/vec4.hpp>
#include <glm/mat4x4.hpp>
#include <glm/trigonometric.hpp>
// Include GLM extensions
\#include &lt;glm/gtc/matrix\_transform.hpp&gt;
glm::mat4 transform(
glm::vec2 const& Orientation,
glm::vec3 const& Translate,
glm::vec3 const& Up)
{
#include <glm/gtc/matrix_transform.hpp>
glm::mat4 transform(glm::vec2 const& Orientation, glm::vec3 const& Translate, glm::vec3 const& Up)
{
glm::mat4 Proj = glm::perspective(glm::radians(45.f), 1.33f, 0.1f, 10.f);
glm::mat4 ViewTranslate = glm::translate(glm::mat4(1.f), Translate);
glm::mat4 ViewRotateX = glm::rotate(ViewTranslate, Orientation.y, Up);
glm::mat4 View = glm::rotate(ViewRotateX, Orientation.x, Up);
glm::mat4 Model = glm::mat4(1.0f);
return Proj \* View \* Model;
}
return Proj * View * Model;
}
```
### 1.4. Dependencies {#dependencies .HeadingB}
-----------------
### 1.4. Dependencies
When &lt;glm/glm.hpp&gt; is included, GLM provides all the GLSL features
it implements in C++.
@ -203,8 +191,7 @@ GLM is built with a C++ 11 compiler in which case
If neither are detected, GLM will rely on its own implementation of
static assert.
2. Swizzle operators {#swizzle-operators .HeadingA}
====================
## 2. Swizzle operators
A common feature of shader languages like GLSL is the swizzle operators.
Those allow selecting multiple components of a vector and change their
@ -214,20 +201,16 @@ components vector. With GLSL, swizzle operators can be both R-values and
L-values. Finally, vector components can be accessed using “xyzw”,
“rgba” or “stpq”.
-----------------
vec4 A;
```cpp
vec4 A;
vec2 B;
...
vec2 B;
B.yx = A.wy;
B = A.xx;
...
B.yx = A.wy;
B = A.xx;
Vec3 C = A.bgr;
-----------------
-----------------
vec3 C = A.bgr;
```
GLM supports a subset of this functionality as described in the
following sub-sections. Swizzle operators are disabled by default. To
@ -235,71 +218,50 @@ enable them GLM\_SWIZZLE must be defined before any inclusion of
&lt;glm/glm.hpp&gt;. Enabling swizzle operators will massively increase
the size of compiled files and the compilation time.
2.1. Default C++98 implementation {#default-c98-implementation .HeadingB}
---------------------------------
### 2.1. Default C++98 implementation {#default-c98-implementation .HeadingB}
The C++98 implementation exposes the R-value swizzle operators as member
functions of vector types.
----------------------------------------------------
\#define GLM\_SWIZZLE
```cpp
#define GLM_SWIZZLE
#include <glm/glm.hpp>
\#include &lt;glm/glm.hpp&gt;
void foo()
{
glm::vec4 ColorRGBA(1.0f, 0.5f, 0.0f, 1.0f);
glm::vec3 ColorBGR = ColorRGBA.bgr();
...
void foo()
glm::vec3 PositionA(1.0f, 0.5f, 0.0f, 1.0f);
glm::vec3 PositionB = PositionXYZ.xyz() \* 2.0f;
...
{
> glm::vec4 ColorRGBA(1.0f, 0.5f, 0.0f, 1.0f);
>
> glm::vec3 ColorBGR = ColorRGBA.bgr();
>
> …
>
> glm::vec3 PositionA(1.0f, 0.5f, 0.0f, 1.0f);
>
> glm::vec3 PositionB = PositionXYZ.xyz() \* 2.0f;
>
> …
>
> glm::vec2 TexcoordST(1.0f, 0.5f);
>
> glm::vec4 TexcoordSTPQ = TexcoordST.stst();
>
> …
}
----------------------------------------------------
----------------------------------------------------
glm::vec2 TexcoordST(1.0f, 0.5f);
glm::vec4 TexcoordSTPQ = TexcoordST.stst();
...
}
```
Swizzle operators return a copy of the component values hence they cant
be used as L-values to change the value of the variables.
----------------------------------------------------------------
\#define GLM\_FORCE\_SWIZZLE
```cpp
#define GLM_FORCE_SWIZZLE
#include <glm/glm.hpp>
\#include &lt;glm/glm.hpp&gt;
void foo()
{
> glm::vec3 A(1.0f, 0.5f, 0.0f);
void foo()
{
glm::vec3 A(1.0f, 0.5f, 0.0f);
// /!\\ No compiler error but A is not affected
// This code modify the components of an anonymous copy.
A.bgr() = glm::vec3(2.0f, 1.5f, 1.0f); // A is not modified!
...
}
```
> A.bgr() = glm::vec3(2.0f, 1.5f, 1.0f); // A is not modified!
>
> …
}
----------------------------------------------------------------
----------------------------------------------------------------
2.2. Anonymous union member implementation {#anonymous-union-member-implementation .HeadingB}
-------------------------------------------
### 2.2. Anonymous union member implementation
Visual C++ supports anonymous structures in union, which is a
non-standard language extension, but it enables a very powerful
@ -308,34 +270,25 @@ swizzle operators and a syntax that doesnt require parentheses in some
cases. This implementation is only enabled when the language extension
is enabled and GLM\_SWIZZLE is defined.
------------------------------------------------
\#define GLM\_FORCE\_SWIZZLE
```cpp
#define GLM_FORCE_SWIZZLE
#include <glm/glm.hpp>
\#include &lt;glm/glm.hpp&gt;
void foo()
{
> glm::vec4 ColorRGBA(1.0f, 0.5f, 0.0f, 1.0f);
void foo()
{
glm::vec4 ColorRGBA(1.0f, 0.5f, 0.0f, 1.0f);
// l-value:
> glm::vec4 ColorBGRA = ColorRGBA.bgra;
glm::vec4 ColorBGRA = ColorRGBA.bgra;
// r-value:
> ColorRGBA.bgra = ColorRGBA;
ColorRGBA.bgra = ColorRGBA;
// Both l-value and r-value
> ColorRGBA.bgra = ColorRGBA.rgba;
>
> …
}
------------------------------------------------
------------------------------------------------
ColorRGBA.bgra = ColorRGBA.rgba;
...
}
```
Anonymous union member swizzle operators dont return vector types
(glm::vec2, glm::vec3 and glm::vec4) but implementation specific objects