Core profile renderer skeleton

src/draw_opengl_core.c

@@ -0,0 +1,152 @@
+#include "draw.h"
+#include "maths.h"
+#include <GL/gl3w.h>
+#include <SDL_video.h>
+#include <stdbool.h>
+
+#define OPENGL_VERSION_MAJOR 3
+#define OPENGL_VERSION_MINOR 3
+
+static SDL_GLContext* ctx = NULL;
+static SDL_Window* window = NULL;
+static uint32_t colour    = 0x00000000;
+static uint32_t clrColour = 0x00000000;
+static bool antialias     = false;
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-function"
+static void GlErrorCb(
+	GLenum source,
+	GLenum type,
+	GLuint id,
+	GLenum severity,
+	GLsizei length,
+	const GLchar* message,
+	const GLvoid* userParam)
+{
+	if (severity != GL_DEBUG_SEVERITY_NOTIFICATION)
+		printf("%s\n", message);
+}
+#pragma clang diagnostic pop
+
+
+void DrawWindowHints(void)
+{
+	SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1); // Enable MSAA
+	SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 8); // 8x MSAA
+
+	// Legacy OpenGL profile
+	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, OPENGL_VERSION_MAJOR);
+	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, OPENGL_VERSION_MINOR);
+	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+}
+
+int InitDraw(SDL_Window* _window)
+{
+	window = _window;
+	ctx = SDL_GL_CreateContext(window);
+	if (ctx == NULL || window == NULL || SDL_GL_MakeCurrent(window, ctx))
+	{
+		fprintf(stderr, "%s\n", SDL_GetError());
+		return -1;
+	}
+
+	// Load Core profile extensions
+	if (gl3wInit() != GL3W_OK)
+	{
+		fprintf(stderr, "Failed to init Core profile\n");
+		return -1;
+	}
+	if (!gl3wIsSupported(OPENGL_VERSION_MAJOR, OPENGL_VERSION_MINOR))
+	{
+		fprintf(stderr, "OpenGL %d.%d unsupported\n", 3, 3);
+		return -1;
+	}
+
+	// Set debug callback
+#if !defined NDEBUG && !defined __APPLE__
+	glDebugMessageCallback(GlErrorCb, nullptr);
+	glEnable(GL_DEBUG_OUTPUT);
+#endif
+
+	SDL_GL_SetSwapInterval(1); // Enable vsync
+
+	// Detect if MSAA is available & active
+	int res;
+	if (SDL_GL_GetAttribute(SDL_GL_MULTISAMPLEBUFFERS, &res) == 0 && res == 1)
+		if (SDL_GL_GetAttribute(SDL_GL_MULTISAMPLESAMPLES, &res) == 0 && res > 0)
+			antialias = true;
+
+	return 0;
+}
+
+void QuitDraw(void)
+{
+	SDL_GL_MakeCurrent(window, NULL);
+	SDL_GL_DeleteContext(ctx);
+	ctx = NULL;
+	window = NULL;
+}
+
+
+size GetDrawSizeInPixels(void)
+{
+	size out;
+	SDL_GL_GetDrawableSize(SDL_GL_GetCurrentWindow(), &out.w, &out.h);
+	return out;
+}
+
+void SetDrawViewport(size size)
+{
+	glViewport(0, 0, size.w, size.h);
+}
+
+
+void SetDrawColour(uint32_t c)
+{
+	colour = c;
+}
+
+void DrawClear(void)
+{
+	if (clrColour != colour)
+	{
+		const float mul = 1.0f / 255.0f;
+		glClearColor(
+			(GLclampf)((colour & 0xFF000000) >> 24) * mul,
+			(GLclampf)((colour & 0x00FF0000) >> 16) * mul,
+			(GLclampf)((colour & 0x0000FF00) >>  8) * mul,
+			(GLclampf)((colour & 0x000000FF)) * mul);
+		clrColour = colour;
+	}
+	glClear(GL_COLOR_BUFFER_BIT);
+}
+
+void DrawPoint(int x, int y)
+{
+
+}
+
+void DrawRect(int x, int y, int w, int h)
+{
+
+}
+
+void DrawLine(int x1, int y1, int x2, int y2)
+{
+
+}
+void DrawCircleSteps(int x, int y, int r, int steps)
+{
+
+}
+
+void DrawArcSteps(int x, int y, int r, int startAng, int endAng, int steps)
+{
+
+}
+
+void DrawPresent(void)
+{
+	SDL_GL_SwapWindow(window);
+}