How to Shaders

Last updated 8 months ago
Intro to the engine's shading API - GLSLProgram
Manage shaders via the GLSLProgram
GLSLProgram.hpp - class declarations
GLSLProgram.cpp - class implementation
Example shader implementations
Basic pixel position & color manipulation.
Vertex
Fragment
Geometry
Tesselation
Tesselation control
shader.vert
#version 450 core                                         
                                
uniform mat4 model_view;
uniform mat4 projection;
								
layout(location = 0) in vec4 position;
​
layout(location = 0) out vec4 vertex_pos;
                                    
void main(void)
{
    gl_Position = projection * model_view * position;
    vertex_pos = position;
}
shader.frag
#version 450 core
​
struct material
{
	vec4 emissive;
};
​
// Incoming vertex position
layout(location = 0) in vec4 vertex_pos;
​
uniform material mat;
 
out vec4 outputF;
​
void main(void)    
{                       
    outputF = mat.emissive;
}
shader.geom
#version 450 core
​
layout (triangles) in;
layout (points, max_vertices = 3) out;
​
void main(void)
{
	int i = 0;
	do
	{
		gl_Position = gl_in[i].gl_Position;
		EmitVertex();
	} while (i++ < gl_in.length());
	EndPrimitive();
}
shader.tes
#version 450 core
​
layout (triangles, equal_spacing, cw) in;
​
void main(void)
{
	gl_Position = (gl_TessCoord.x * gl_in[0].gl_Position +
				   gl_TessCoord.y * gl_in[1].gl_Position +
				   gl_TessCoord.z * gl_in[2].gl_Position);
}
shader.tcs
#version 450 core
​
layout (vertices = 3) out;
​
void main(void)
{
	// Only if I am invocation 0...
	if(gl_InvocationID == 0)
	{
		gl_TessLevelInner[0] = 5.0;
		gl_TessLevelOuter[0] = 5.0;
		gl_TessLevelOuter[1] = 5.0;
		gl_TessLevelOuter[2] = 5.0;
	}
​
	// Everybody copies their input to their output
	gl_out[gl_InvocationID].gl_Position = gl_in[gl_InvocationID].gl_Position;
}
 Require the shader class in your application
#include "graphics/shaders/GLSLProgram.hpp"
 Instantiate a shader program object
// using default ctor
GLSLProgram shader;
 Compile & Build the shader program from your sources
Vertex & Fragment shaders are both enough and mandatory to start with.
std::string and char* sources are accepted
can be file path or a shader code as a string
Example
Compile shader from file
// load and compile shaders
shader.CompileShaderFile("res/shaders/example.vert", GLSLShader::GLSLShaderType::VERTEX);
shader.CompileShaderFile("res/shaders/example.frag", GLSLShader::GLSLShaderType::FRAGMENT);
Build the comiled shader
// link the shades into the program
shader.Build();
Use the shader or change the shader that is currently in use
Bind current shader
shader.Enable();
Unbind current shader
shader.Disable();
Renderer Setup
Sample Scene