Wrestled down how I was misunderstanding the way textures are bound and managed.

TODO.md

@@ -3,3 +3,4 @@
   * Character mapping for the fonts
   * Checks for errors in analyzer
   * Resource prep: images, fonts, font glyphs
+* Images if images are first they don't render correctly, just black

lua/builder_test.lua

@@ -11,7 +11,7 @@ slide{
   h1 "Here's Mine",
   image{
     src="assets/test.jpg"
-  }
+  },
 }
 
 slide{

src/engine.cpp

@@ -82,11 +82,11 @@ void Engine::init() {
   setup();
 
   text = std::make_shared<Text>();
+  text->load_font();
+
   screen = std::make_shared<Screen>();
   framebuffer = std::make_shared<FrameBuffer>();
 
-  text->load_font();
-  // BUG: this will fail if it's before text.load_font
   deck.analyze();
 
   screen->init();

src/image.cpp

@@ -34,12 +34,15 @@ unsigned int image_to_texture(unsigned char *data, int width, int height, int nr
   }
 
   glBindTexture(GL_TEXTURE_2D, textureID);
+
   glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
   glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
+  glBindTexture(GL_TEXTURE_2D, 0);
+
   return textureID;
 }
 
@@ -55,16 +58,24 @@ void Image::load(const std::string& filename) {
 
 void Image::render() {
   shader.use();
-  shader.setInt("texture1", texture_id);
+
-  glBindVertexArray(image_vao);
+  // use the correct texture unit
+  glActiveTexture(GL_TEXTURE0 + texture_unit);
     glBindTexture(GL_TEXTURE_2D, texture_id);
+
+  // then I don't need to set this every time I render
+  glBindVertexArray(image_vao);
   glDrawArrays(GL_TRIANGLES, 0, 6);
 
+  // unbind
   glBindTexture(GL_TEXTURE_2D, 0);
   glBindVertexArray(0);
 }
 
 Image::Image() {
+  shader.use();
+  shader.setTextureUnit("texture1", texture_unit);
+
   glGenVertexArrays(1, &image_vao);
   glGenBuffers(1, &image_vbo);
 
@@ -72,12 +83,14 @@ Image::Image() {
   glBindBuffer(GL_ARRAY_BUFFER, image_vbo);
   glBufferData(GL_ARRAY_BUFFER, sizeof(VERTICES), &VERTICES, GL_STATIC_DRAW);
 
-  // position attrib
+  // position attrib location=0
-  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
   glEnableVertexAttribArray(0);
+  glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)0);
 
-  // color attribute
+  // color attribute location = 1
   glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 4 * sizeof(float), (void*)(2 * sizeof(float)));
   glEnableVertexAttribArray(1);
+
+  // unbind
   glBindVertexArray(0);
 }

src/image.hpp

@@ -7,6 +7,7 @@ struct Image {
   unsigned int image_vao = UINT_MAX;
   unsigned int image_vbo = UINT_MAX;
   unsigned int texture_id = UINT_MAX;
+  unsigned int texture_unit = 1;
   int width = 0;
   int height = 0;
   int nrComponents = 0;

src/shader.cpp

@@ -109,6 +109,14 @@ void Shader::setInt(const std::string &name, int value) const {
   glUniform1i(uniform, value);
 }
 
+/*
+ * Mostly for self-documenting purposes, it just does an int.
+ */
+void Shader::setTextureUnit(const std::string &name, int value) const {
+  auto uniform = glGetUniformLocation(ID, name.c_str());
+  glUniform1i(uniform, value);
+}
+
 void Shader::setFloat(const std::string &name, float value) const {
   auto uniform = glGetUniformLocation(ID, name.c_str());
   glUniform1f(uniform, value);

src/shader.hpp

@@ -26,6 +26,7 @@ public:
   void use() const;
   void setBool(const std::string &name, bool value) const;
   void setInt(const std::string &name, int value) const;
+  void setTextureUnit(const std::string &name, int value) const;
   void setFloat(const std::string &name, float value) const;
   void setVec4(const std::string &name, float v1, float v2, float v3, float v4) const;
   void setVec4(const std::string &name, const glm::vec4& value) const;

src/text.cpp

@@ -52,6 +52,21 @@ void Text::render(const std::string& text, float x, float y, float scale, glm::v
   glBindTexture(GL_TEXTURE_2D, 0);
 }
 
+Text::Text() {
+  // can you create this before load_font?
+  glGenVertexArrays(1, &text_vao);
+  glGenBuffers(1, &text_vbo);
+
+  glBindVertexArray(text_vao);
+  glBindBuffer(GL_ARRAY_BUFFER, text_vbo);
+  glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 4, NULL, GL_DYNAMIC_DRAW);
+
+  glEnableVertexAttribArray(0);
+  glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
+
+  glBindVertexArray(0);
+}
+
 void Text::load_font() {
   FT_Library ft;
   int fail = FT_Init_FreeType(&ft);
@@ -93,22 +108,12 @@ void Text::load_font() {
         glm::ivec2(face->glyph->bitmap.width, face->glyph->bitmap.rows),
         glm::ivec2(face->glyph->bitmap_left, face->glyph->bitmap_top),
         static_cast<unsigned int>(face->glyph->advance.x));
-  }
 
     // unbind
     glBindTexture(GL_TEXTURE_2D, 0);
+  }
 
   // cleanup
   FT_Done_Face(face);
   FT_Done_FreeType(ft);
-
-  // create teh vao/vbo
-  glGenVertexArrays(1, &text_vao);
-  glGenBuffers(1, &text_vbo);
-  glBindVertexArray(text_vao);
-  glBindBuffer(GL_ARRAY_BUFFER, text_vbo);
-  glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 6 * 4, NULL, GL_DYNAMIC_DRAW);
-  glEnableVertexAttribArray(0);
-  glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 4 * sizeof(float), 0);
-  glBindVertexArray(0);
 }

src/text.hpp

@@ -21,4 +21,5 @@ struct Text {
 
   void render(const std::string& text, float x, float y, float scale, glm::vec3 color);
   void load_font();
+  Text();
 };