Solid Color Fill

Learn the most basic shader concepts and create solid color fill effects. Understand the role of gl_FragColor and RGBA color mode.

Overview

• Follow the steps to complete the exercise.

Learning Objectives

• Understand the basic structure of a GLSL shader and the entry point main() function.
• Learn how to use gl_FragColor to output fragment color.
• Master the RGBA color model and how to represent color values in GLSL (0.0 to 1.0 range).
• Be able to write a minimal GLSL shader to fill the entire canvas with a single color.

Inputs

• float u_time — Time in seconds.
• vec2 u_resolution — Canvas size in pixels.

Key Concepts

• Animate with u_time + sin/cos.

float pulse = sin(u_time) * 0.5 + 0.5;

How To Implement (Step-by-step)

• Animate with u_time (optional).

Self-check

• Does it compile without errors?
• Does the output match the goal?
• Are key values kept in [0,1]?

Common Mistakes

• If output is black, check your mask/factor isn’t always 0.