Add README

README.txt

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+glslview
+========
+
+glslview is a simple program to run GLSL fragment shaders and interact with them.
+
+glslview will render a simple fullscreen rectangle, the shader will determine each
+pixel's color.
+
+The glslwrite tool can be used to write the generated frames to PNG files
+(with transparency support!).
+
+You will need a graphics adapter and drivers with modern OpenGL/GLSL support.
+
+Building
+~~~~~~~~
+
+glslview has been tested on Linux only, but it should work on other systems as well.
+If it doesn't, I'm happy to take patches.
+
+glslview has the following dependencies:
+
+* SDL2
+* libGL
+* libGLEW
+
+glslwrite additionally depends on libpng.
+
+On Linux, glslview will use inotify to watch the loaded shader file for changes.
+
+
+Running
+~~~~~~~
+
+Shader
+------
+
+glslview will supply the following uniform parameters to the shader:
+
+vec2 res
+    The current resolution of the window
+
+float time
+    Current time in milliseconds (by default since start of the program)
+
+int param0, param1, param2
+    Modifiable parameters, 0 by default
+
+The shader must define an output vec4 called "fragColor" into which the fragment color
+is to be written.
+
+See the examples provided with the source for more information. The "symmetry"
+example makes use of all parameters.
+
+
+Command line
+------------
+
+    glslview <options> <shader>
+    glslwrite <options> <shader> <output directory>
+
+
+Common options:
+
+-w <width>
+    Initial window width (default: 800)
+
+-h <height>
+    Initial window height (default: 800)
+
+-0, -1, -2 <param>
+    Initial value for the shader parameters
+
+
+glslview options:
+
+-s <speed>
+    Initial speed factor (default: 1.0, negative values make time run backwards)
+
+-t <time>
+    Initial time value (default: 0.0)
+
+
+glslwrite options:
+
+-s <step>
+    Time step between frames (default: 20.0)
+
+-f <frame>
+    Number of frames to generate (default: run forever)
+
+
+glslview control
+----------------
+
++/-, scroll wheel
+    Change speed
+
+=
+    Reset speed
+
+<
+    Run backwards
+
+>
+    Run forwards
+
+r
+    Reset time
+
+R
+    Reset parameters
+
+Page up/down
+    Modify param0
+
+Left/right
+    Modify param1
+
+Up/down
+    Modify param2
+
+Escape
+    Quit