CODEWITHSUNDEEP
opengl
Verim
Verim

Reputation: 1125

Best practice: Mutiple usage of same shader

I wonder what is the best way to reuse the same shader multiple times. I have different Objects which use the same shader. Is it okay to compile & link the same shader for every object again, or should i better compile / link just once?

The question is: does OpenGL cache the compiled shaders or would they compiled again?

And how about linking: should I use one program multiple times for different objects or is it also okay to recompile multiple programs with equal shaders?

/** Option 1: Using same equal shaders multiple times **/
int vertexShader1 = loadShader(GL_VERTEX_SHADER, vertexShaderCode);
int vertexShader2 = loadShader(GL_VERTEX_SHADER, vertexShaderCode);
int vertexShader3 = loadShader(GL_VERTEX_SHADER, vertexShaderCode);

int program1 = glCreateProgram();
int program2 = glCreateProgram();
int program3 = glCreateProgram();

glAttachShader(program1, vertexShader1);
glAttachShader(program2, vertexShader2);
glAttachShader(program3, vertexShader3);

glLinkProgram(program1);
glLinkProgram(program2);
glLinkProgram(program3);



/** Option 2: Using same shader multiple times **/
int vertexShader = loadShader(GL_VERTEX_SHADER, vertexShaderCode);
int program1 = glCreateProgram();
int program2 = glCreateProgram();
int program3 = glCreateProgram();

glAttachShader(program1, vertexShader);
glAttachShader(program2, vertexShader);
glAttachShader(program3, vertexShader);

glLinkProgram(program1);
glLinkProgram(program2);
glLinkProgram(program3);



/** Option 3: Reuse program **/
int vertexShader = loadShader(GL_VERTEX_SHADER, vertexShaderCode);

int program = glCreateProgram();

glAttachShader(program, vertexShader);

glLinkProgram(program);

Upvotes: 0

Views: 703

Answers (1)

datenwolf
datenwolf

Reputation: 162164

If in doubt: Minimize the number of objects and reuse. Switching shaders is amoing the more costly operations in OpenGL and relying on the driver to deduplicate is bad practice.

Upvotes: 1

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