Rework sprite API

source/glerminal-private.h

@@ -3,24 +3,23 @@
 
 #include "glerminal.h"
 
+#include <stb_image.h>
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
 
-#include <stdexcept>
-#ifdef _DEBUG
 #include <fstream>
-#endif
+#include <stdexcept>
 
 namespace glerminal
 {
 	constexpr unsigned int SCREEN_WIDTH = 1280;
 	constexpr unsigned int SCREEN_HEIGHT = 800;
-	constexpr unsigned int CELL_SIZE = GLERMINAL_CELL_SIZE;
+	constexpr unsigned int CELL_SIZE = 8;
 	constexpr unsigned int CELL_SCALE = 4;
+	constexpr unsigned int LAYER_COUNT = 256;
 	constexpr unsigned int GRID_WIDTH = SCREEN_WIDTH / (CELL_SIZE * CELL_SCALE);
 	constexpr unsigned int GRID_HEIGHT = SCREEN_HEIGHT / (CELL_SIZE * CELL_SCALE);
 	constexpr unsigned int GRID_AREA = GRID_WIDTH * GRID_HEIGHT;
-	constexpr unsigned int LAYER_COUNT = 256;
 
 	class glerminal
 	{
@@ -43,8 +42,7 @@ namespace glerminal
 		void offset(unsigned char x, unsigned char y, unsigned char layer, float x_offset, float y_offset);
 		void layer_color(unsigned char layer, unsigned int color);
 		void layer_scale(unsigned char layer, float scale);
-
-		void update_sprite(unsigned char id, glerminal_sprite sprite);
+		void load_atlas(unsigned char w, unsigned char h, const unsigned int* data);
 
 	private:
 		// glfw data

source/glerminal.cpp

@@ -1,3 +1,6 @@
+#define STB_IMAGE_IMPLEMENTATION
+#define STBI_ONLY_PNG
+#define STBI_MAX_DIMENSIONS 128
 #include "glerminal-private.h"
 
 #define GRID_SIZE_UNIFORM_NAME "grid_size"
@@ -255,10 +258,26 @@ namespace glerminal
 		m_layer_scales[layer] = scale;
 	}
 
-	void glerminal::update_sprite(unsigned char id, glerminal_sprite sprite)
+	void glerminal::load_atlas(unsigned char w, unsigned char h, const unsigned int* data)
 	{
-		// does this work?
-		reinterpret_cast<glerminal_sprite*>(m_sprites)[id] = sprite;
+		// each row of the atlas
+		for (int j = 0; j < h; j++)
+		{
+			// each column of the atlas
+			for (int i = 0; i < w; i++)
+			{
+				// each row of the individual sprite
+				for (int k = 0; k < CELL_SIZE; k++)
+				{
+					// offset from base address in atlas layout
+					const unsigned int src_offset = i + k * w + j * w * CELL_SIZE;
+					// offset from base address in array layout
+					const unsigned int dst_offset = k + i * CELL_SIZE + j * w * CELL_SIZE;
+
+					memcpy(m_sprites + CELL_SIZE * dst_offset, data + CELL_SIZE * src_offset, CELL_SIZE * sizeof(unsigned int));
+				}
+			}
+		}
 	}
 
 	void glerminal::init_glfw()
@@ -682,9 +701,29 @@ void glerminal_layer_scale(unsigned char layer, float scale)
 	GLERMINAL_G->layer_scale(layer, scale);
 }
 
-void glerminal_update_sprite(unsigned char id, glerminal_sprite sprite)
+void glerminal_load_sprites_file(const char* filename)
 {
 	if (!GLERMINAL_G) { return; }
 
-	GLERMINAL_G->update_sprite(id, sprite);
+	int w, h;
+	stbi_uc* const buffer = stbi_load(filename, &w, &h, nullptr, 4);
+
+	// verify atlas size is a multiple of CELL_SIZE in each dimension
+	if (w % glerminal::CELL_SIZE == 0 && h % glerminal::CELL_SIZE == 0)
+	{
+		GLERMINAL_G->load_atlas(w / glerminal::CELL_SIZE, h / glerminal::CELL_SIZE, reinterpret_cast<unsigned int*>(buffer));
+	}
+
+	stbi_image_free(buffer);
+}
+
+void glerminal_load_sprites_buffer(unsigned char width, unsigned char height, const unsigned int* buffer)
+{
+	if (!GLERMINAL_G) { return; }
+
+	// verify atlas size is a multiple of CELL_SIZE in each dimension
+	if (width % glerminal::CELL_SIZE == 0 && height % glerminal::CELL_SIZE == 0)
+	{
+		GLERMINAL_G->load_atlas(width / glerminal::CELL_SIZE, height / glerminal::CELL_SIZE, buffer);
+	}
 }