module prova.graphics.shaderprograms.sprite;

import prova.graphics.shaderprograms;

/**
 * Uniforms:
 * - mat4 transform
 * - sampler2D sprite;
 * - vec4 clip
 * - vec4 tint
 */
class SpriteShaderProgram : ShaderProgram
{
  ///
  this()
  {
    super();

    attachVertexShader(
      "#version 130
      uniform mat4 transform;
      in vec4 vertexPosition;
      out vec2 position;

      void main() {
        position = vertexPosition.xy;
        gl_Position = transform * vertexPosition;
      }"
    );

    attachFragmentShader(
      "#version 130
      uniform sampler2D sprite;
      uniform vec4 clip;
      uniform vec4 tint;

      in vec2 position;
      out vec4 fragmentColor;

      void main() {
        vec2 texPos = vec2(
          clip.x + (position.x) * clip.z,
          clip.y + (position.y) * clip.w
        );

        fragmentColor = texture(sprite, texPos) * tint;

        if(fragmentColor.a == 0)
          discard;
      }"
    );

    link();
  }
}