feat(render): style, GLSL line/text pipelines, staging batches, bitmap font

src/render/program.cpp

@@ -0,0 +1,50 @@
+#include <plot/render/program.hpp>
+
+#include <plot/render/shaders.hpp>
+
+namespace plot::render {
+
+bool LineProgram::create(Status* st) noexcept {
+  // plot::gl::Program::from_source() reports Unsupported while
+  // plot::gl::available() is false and GLFailure when the driver rejects the
+  // GLSL. Propagating it is the whole point of returning a bool here: the
+  // caller must not end up drawing with a program that never linked.
+  program_ = gl::Program::from_source(kLineVS, kLineFS, st);
+  return program_.id() != 0;
+}
+
+void LineProgram::set_scale(Vec2 data_to_px) const noexcept {
+  program_.set_uniform("u_scale", data_to_px);
+}
+
+void LineProgram::set_offset(Vec2 px) const noexcept { program_.set_uniform("u_offset", px); }
+
+void LineProgram::set_viewport(Vec2 px) const noexcept { program_.set_uniform("u_viewport", px); }
+
+void LineProgram::set_width(f32 px) const noexcept { program_.set_uniform("u_width", px); }
+
+void LineProgram::set_color(Color color) const noexcept { program_.set_uniform("u_color", color); }
+
+bool TextProgram::create(Status* st) noexcept {
+  program_ = gl::Program::from_source(kTextVS, kTextFS, st);
+  if (program_.id() == 0) {
+    return false;
+  }
+  // The atlas is bound to texture unit 0 by plot::gl::Texture::bind(), so the
+  // sampler has to point there. It is set once, here, not per frame.
+  program_.use();
+  program_.set_uniform_int("u_atlas", 0);
+  return true;
+}
+
+void TextProgram::set_viewport(Vec2 px) const noexcept { program_.set_uniform("u_viewport", px); }
+
+void TextProgram::set_px_range(Vec2 px) const noexcept { program_.set_uniform("u_px_range", px); }
+
+void TextProgram::set_texture_size(Vec2 texels) const noexcept {
+  program_.set_uniform("u_tex_size", texels);
+}
+
+void TextProgram::set_color(Color color) const noexcept { program_.set_uniform("u_color", color); }
+
+}  // namespace plot::render