Change font texture from RECTANGLE to 2D

Make new texture function for making 2D textures instead of RECTANGLE
textures.

Pass in scale factor from texel coordinates to UV coordinates.

Change text and text80 fragment shaders to scale texel coordinates
to UV for sampler for font_texture.

Use sampler2D instead of sampler2DRect for font_texture

interface.cpp

@@ -92,6 +92,7 @@ GLuint textport_to_screen_location;
 GLuint textport_foreground_location;
 GLuint textport_background_location;
 GLuint textport_font_texture_location;
+GLuint textport_font_texture_coord_scale_location;
 
 GLuint text80_program;
 GLuint textport80_texture_location;
@@ -103,6 +104,7 @@ GLuint textport80_to_screen_location;
 GLuint textport80_foreground_location;
 GLuint textport80_background_location;
 GLuint textport80_font_texture_location;
+GLuint textport80_font_texture_coord_scale_location;
 
 GLuint lores_program;
 GLuint lores_texture_location;
@@ -142,17 +144,54 @@ tuple<float,bool> get_paddle(int num)
     return make_tuple(paddle_values[num], paddle_buttons[num]);
 }
 
+
 static void CheckOpenGL(const char *filename, int line)
 {
     int glerr;
+    bool stored_exit_flag = false;
+    bool exit_on_error;
 
-    if((glerr = glGetError()) != GL_NO_ERROR) {
+    if(!stored_exit_flag) {
+        exit_on_error = getenv("EXIT_ON_OPENGL_ERROR") != NULL;
+        stored_exit_flag = true;
+    }
+
+    while((glerr = glGetError()) != GL_NO_ERROR) {
         printf("GL Error: %04X at %s:%d\n", glerr, filename, line);
+        if(exit_on_error)
+            exit(1);
     }
 }
 
-GLuint upper_screen_area;
+struct vertex_attribute_buffer
-GLuint lower_screen_area;
+{
+    GLuint buffer;
+    GLuint which;
+    GLuint count;
+    GLenum type;
+    GLboolean normalized;
+    GLsizei stride;
+    void bind() const 
+    {
+        glBindBuffer(GL_ARRAY_BUFFER, buffer);
+        CheckOpenGL(__FILE__, __LINE__);
+        glVertexAttribPointer(which, count, type, normalized, stride, 0);
+        CheckOpenGL(__FILE__, __LINE__);
+        glEnableVertexAttribArray(which);
+        CheckOpenGL(__FILE__, __LINE__);
+    }
+};
+
+struct vertex_array : public vector<vertex_attribute_buffer>
+{
+    void bind()
+    {
+        for(auto attr : *this) {
+            attr.bind();
+        }
+    }
+};
+
 const int raster_coords_attrib = 0;
  
 static bool CheckShaderCompile(GLuint shader, const std::string& shader_name)
@@ -333,7 +372,8 @@ static const char *text_fragment_shader = "\n\
     uniform int blink;\n\
     uniform vec4 foreground;\n\
     uniform vec4 background;\n\
-    uniform usampler2DRect font_texture;\n\
+    uniform vec2 font_texture_coord_scale;\n\
+    uniform usampler2D font_texture;\n\
     uniform usampler2DRect textport_texture;\n\
     \n\
     out vec4 color;\n\
@@ -365,9 +405,9 @@ static const char *text_fragment_shader = "\n\
             character = character - 224u + 64u;\n\
         else \n\
             character = 33u;\n\
-        uvec2 inglyph = uvec2(uint(raster_coords.x) % 7u + 1u, uint(raster_coords.y) % 8u);\n\
+        uvec2 inglyph = uvec2(uint(raster_coords.x) % 7u, uint(raster_coords.y) % 8u);\n\
         uvec2 infont = inglyph + uvec2(0, character * 8u);\n\
-        uint pixel = texture(font_texture, infont).x;\n\
+        uint pixel = texture(font_texture, infont * font_texture_coord_scale).x;\n\
         float value;\n\
         if(inverse)\n\
             color = mix(background, foreground, 1.0 - pixel / 255.0);\n\
@@ -380,7 +420,8 @@ static const char *text80_fragment_shader = "\n\
     uniform int blink;\n\
     uniform vec4 foreground;\n\
     uniform vec4 background;\n\
-    uniform usampler2DRect font_texture;\n\
+    uniform vec2 font_texture_coord_scale;\n\
+    uniform usampler2D font_texture;\n\
     uniform usampler2DRect textport_texture;\n\
     uniform usampler2DRect textport_aux_texture;\n\
     \n\
@@ -417,9 +458,9 @@ static const char *text80_fragment_shader = "\n\
             character = character - 224u + 64u;\n\
         else \n\
             character = 33u;\n\
-        uvec2 inglyph = uvec2(uint(raster_coords.x * 2) % 7u + 1u, uint(raster_coords.y) % 8u);\n\
+        uvec2 inglyph = uvec2(uint(raster_coords.x * 2) % 7u, uint(raster_coords.y) % 8u);\n\
         uvec2 infont = inglyph + uvec2(0, character * 8u);\n\
-        uint pixel = texture(font_texture, infont).x;\n\
+        uint pixel = texture(font_texture, infont * font_texture_coord_scale).x;\n\
         float value;\n\
         if(inverse)\n\
             color = mix(background, foreground, 1.0 - pixel / 255.0);\n\
@@ -429,7 +470,6 @@ static const char *text80_fragment_shader = "\n\
 
 static const char *lores_fragment_shader = "\n\
     in vec2 raster_coords;\n\
-    uniform usampler2DRect font_texture;\n\
     uniform usampler2DRect lores_texture;\n\
     \n\
     out vec4 color;\n\
@@ -539,12 +579,12 @@ static GLuint GenerateProgram(const string& shader_name, const string& vertex_sh
     return program;
 }
 
-GLuint make_rectangle_vertex_array(float x, float y, float w, float h)
+vertex_array upper_screen_area;
+vertex_array lower_screen_area;
+
+vertex_array make_rectangle_vertex_array(float x, float y, float w, float h)
 {
-    GLuint array;
+    vertex_array array;
-    glGenVertexArrays(1, &array);
-    glBindVertexArray(array);
-    CheckOpenGL(__FILE__, __LINE__);
 
     /* just x, y, also pixel coords */
     GLuint vertices;
@@ -560,9 +600,8 @@ GLuint make_rectangle_vertex_array(float x, float y, float w, float h)
     glBufferData(GL_ARRAY_BUFFER, sizeof(coords[0]) * 4, coords, GL_STATIC_DRAW);
     CheckOpenGL(__FILE__, __LINE__);
 
-    glVertexAttribPointer(raster_coords_attrib, 2, GL_FLOAT, GL_FALSE, 0, 0);
+    array.push_back({vertices, raster_coords_attrib, 2, GL_FLOAT, GL_FALSE, 0});
-    glEnableVertexAttribArray(raster_coords_attrib);
+
-    CheckOpenGL(__FILE__, __LINE__);
     return array;
 }
 
@@ -572,7 +611,7 @@ void initialize_screen_areas()
     lower_screen_area = make_rectangle_vertex_array(0, 160, 280, 32);
 }
 
-GLuint initialize_texture(int w, int h, unsigned char *pixels = NULL)
+GLuint initialize_texture_integer(int w, int h, unsigned char *pixels = NULL)
 {
     GLuint texture;
 
@@ -587,6 +626,21 @@ GLuint initialize_texture(int w, int h, unsigned char *pixels = NULL)
     return texture;
 }
 
+GLuint initialize_texture(int w, int h, unsigned char *pixels = NULL)
+{
+    GLuint texture;
+
+    glGenTextures(1, &texture);
+    glBindTexture(GL_TEXTURE_2D, texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    CheckOpenGL(__FILE__, __LINE__);
+    glTexImage2D(GL_TEXTURE_2D, 0, GL_R8UI, w, h, 0, GL_RED_INTEGER, GL_UNSIGNED_BYTE, pixels);
+    CheckOpenGL(__FILE__, __LINE__);
+    return texture;
+}
+
 void set_image_shader(float to_screen[9], GLuint texture, float x, float y)
 {
     glUseProgram(image_program);
@@ -608,6 +662,7 @@ void set_hires_shader(float to_screen[9], GLuint hires_texture, bool color, floa
         glUniformMatrix3fv(hirescolor_to_screen_location, 1, GL_FALSE, to_screen);
         glUniform1f(hirescolor_x_offset_location, x);
         glUniform1f(hirescolor_y_offset_location, y);
+        CheckOpenGL(__FILE__, __LINE__);
 
     } else {
 
@@ -618,6 +673,7 @@ void set_hires_shader(float to_screen[9], GLuint hires_texture, bool color, floa
         glUniformMatrix3fv(hires_to_screen_location, 1, GL_FALSE, to_screen);
         glUniform1f(hires_x_offset_location, x);
         glUniform1f(hires_y_offset_location, y);
+        CheckOpenGL(__FILE__, __LINE__);
     }
 }
 
@@ -629,14 +685,18 @@ void set_textport_shader(float to_screen[9], GLuint textport_texture, int blink,
     glBindTexture(GL_TEXTURE_RECTANGLE, textport_texture);
     glUniform1i(textport_texture_location, 0);
     glActiveTexture(GL_TEXTURE1);
-    glBindTexture(GL_TEXTURE_RECTANGLE, font_texture);
+    glBindTexture(GL_TEXTURE_2D, font_texture);
     glUniform1i(textport_font_texture_location, 1);
+    CheckOpenGL(__FILE__, __LINE__);
+    glUniform2f(textport_font_texture_coord_scale_location, 1.0 / (fonttexture_w - 0), 1.0 / (fonttexture_h - 0));
+    CheckOpenGL(__FILE__, __LINE__);
     glUniform1i(textport_blink_location, blink);
     glUniform1f(textport_x_offset_location, x);
     glUniform1f(textport_y_offset_location, y);
     glUniform4fv(textport_background_location, 1, bg);
     glUniform4fv(textport_foreground_location, 1, fg);
     glUniformMatrix3fv(textport_to_screen_location, 1, GL_FALSE, to_screen);
+    CheckOpenGL(__FILE__, __LINE__);
 }
 
 void set_textport80_shader(float to_screen[9], GLuint textport80_texture, GLuint textport80_aux_texture, int blink, float x, float y, float fg[4], float bg[4])
@@ -656,8 +716,9 @@ void set_textport80_shader(float to_screen[9], GLuint textport80_texture, GLuint
     tex += 1;
     CheckOpenGL(__FILE__, __LINE__);
     glActiveTexture(GL_TEXTURE0 + tex);
-    glBindTexture(GL_TEXTURE_RECTANGLE, font_texture);
+    glBindTexture(GL_TEXTURE_2D, font_texture);
     glUniform1i(textport80_font_texture_location, tex);
+    glUniform2f(textport80_font_texture_coord_scale_location, 1.0 / (fonttexture_w - 1), 1.0 / (fonttexture_h - 1));
     tex += 1;
     glUniform1i(textport80_blink_location, blink);
     glUniform1f(textport80_x_offset_location, x);
@@ -980,14 +1041,14 @@ struct apple2screen : public widget
         set_shader(to_screen, display_mode, false, vid80, (elapsed_millis / 300) % 2, x, y);
         CheckOpenGL(__FILE__, __LINE__);
 
-        glBindVertexArray(upper_screen_area);
+        upper_screen_area.bind();
         CheckOpenGL(__FILE__, __LINE__);
         glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
         CheckOpenGL(__FILE__, __LINE__);
 
         set_shader(to_screen, display_mode, mixed_mode, vid80, (elapsed_millis / 300) % 2, x, y);
 
-        glBindVertexArray(lower_screen_area);
+        lower_screen_area.bind();
         CheckOpenGL(__FILE__, __LINE__);
         glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
         CheckOpenGL(__FILE__, __LINE__);
@@ -1052,14 +1113,14 @@ struct apple2screen : public widget
 struct image_widget : public widget
 {
     GLuint image;
-    GLuint rectangle;
+    vertex_array rectangle;
     int w, h;
 
     image_widget(int w_, int h_, unsigned char *buffer) :
         w(w_),
         h(h_)
     {
-        image = initialize_texture(w, h, buffer);
+        image = initialize_texture_integer(w, h, buffer);
         rectangle = make_rectangle_vertex_array(0, 0, w, h);
     }
 
@@ -1072,7 +1133,7 @@ struct image_widget : public widget
     {
         set_image_shader(to_screen, image, x, y);
 
-        glBindVertexArray(rectangle);
+        rectangle.bind();
         glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
         CheckOpenGL(__FILE__, __LINE__);
     }
@@ -1081,7 +1142,7 @@ struct image_widget : public widget
 struct text_widget : public widget
 {
     GLuint string_texture;
-    GLuint rectangle;
+    vertex_array rectangle;
     string content;
     float fg[4];
     float bg[4];
@@ -1106,7 +1167,7 @@ struct text_widget : public widget
                 bytes.get()[i] = 255;
             i++;
         }
-        string_texture = initialize_texture(i, 1, bytes.get());
+        string_texture = initialize_texture_integer(i, 1, bytes.get());
         rectangle = make_rectangle_vertex_array(0, 0, i * 7, 8);
     }
 
@@ -1119,7 +1180,7 @@ struct text_widget : public widget
     {
         set_textport_shader(to_screen, string_texture, 0, x, y, fg, bg);
 
-        glBindVertexArray(rectangle);
+        rectangle.bind();
         glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
         CheckOpenGL(__FILE__, __LINE__);
     }
@@ -1288,16 +1349,20 @@ toggle *caps_toggle;
 
 void initialize_gl(void)
 {
+    GLuint va;
+    glGenVertexArrays(1, &va);
+    glBindVertexArray(va);
+
     glClearColor(0, 0, 0, 1);
     CheckOpenGL(__FILE__, __LINE__);
 
     font_texture = initialize_texture(fonttexture_w, fonttexture_h, font_bytes);
-    textport_texture[0][0] = initialize_texture(textport_w, textport_h);
+    textport_texture[0][0] = initialize_texture_integer(textport_w, textport_h);
-    textport_texture[0][1] = initialize_texture(textport_w, textport_h);
+    textport_texture[0][1] = initialize_texture_integer(textport_w, textport_h);
-    textport_texture[1][0] = initialize_texture(textport_w, textport_h);
+    textport_texture[1][0] = initialize_texture_integer(textport_w, textport_h);
-    textport_texture[1][1] = initialize_texture(textport_w, textport_h);
+    textport_texture[1][1] = initialize_texture_integer(textport_w, textport_h);
-    hires_texture[0] = initialize_texture(hires_w, hires_h);
+    hires_texture[0] = initialize_texture_integer(hires_w, hires_h);
-    hires_texture[1] = initialize_texture(hires_w, hires_h);
+    hires_texture[1] = initialize_texture_integer(hires_w, hires_h);
     CheckOpenGL(__FILE__, __LINE__);
 
     image_program = GenerateProgram("image", hires_vertex_shader, image_fragment_shader);
@@ -1321,6 +1386,7 @@ void initialize_gl(void)
     text_program = GenerateProgram("textport", text_vertex_shader, text_fragment_shader);
     textport_texture_location = glGetUniformLocation(text_program, "textport_texture");
     textport_font_texture_location = glGetUniformLocation(text_program, "font_texture");
+    textport_font_texture_coord_scale_location = glGetUniformLocation(text_program, "font_texture_coord_scale");
     textport_blink_location = glGetUniformLocation(text_program, "blink");
     textport_x_offset_location = glGetUniformLocation(text_program, "x_offset");
     textport_y_offset_location = glGetUniformLocation(text_program, "y_offset");
@@ -1339,6 +1405,7 @@ void initialize_gl(void)
     textport80_to_screen_location = glGetUniformLocation(text80_program, "to_screen");
     textport80_foreground_location = glGetUniformLocation(text80_program, "foreground");
     textport80_background_location = glGetUniformLocation(text80_program, "background");
+    textport80_font_texture_coord_scale_location = glGetUniformLocation(text80_program, "font_texture_coord_scale");
     CheckOpenGL(__FILE__, __LINE__);
 
     lores_program = GenerateProgram("textport", text_vertex_shader, lores_fragment_shader);