hexgame/src/renderer.cpp

#include <vector>
#include <cmath> // trig functions
#include <cstdlib> // calloc

#include <GL/gl3w.h>
#if defined (_WIN32)
	#include <SDL.h>
#else
	#include <SDL2/SDL.h>
#endif
#include <SDL_image.h>
#include <glm/glm.hpp>
#include <glm/geometric.hpp>
#include <glm/gtc/matrix_transform.hpp>

#include "aixlog.hpp"

#include "hexlib.h"
#include "renderer.h"
#include "render_group.h"

#define DEFAULT_VERTEX_SHADER_FILE "../data/default.vs"
#define DEFAULT_FRAGMENT_SHADER_FILE "../data/default.fs"
#define MAX_LIGHTS 10 // NOTE: needs to match the fragment shader source

struct clear_col
{
	real32 R;
	real32 G;
	real32 B;
	real32 A;
};
clear_col g_clear_col { 75.f / 255.f, 135.f / 255.f, 135.f / 255.f, 1.f };


// forward declarations
void initMatrices(projection_type p);
void openglDebugCallback(GLenum source, GLenum type, GLuint id, GLenum severity,
					GLsizei length, const GLchar* message, const void* userParam);
// TODO: move hex logic to new file
bool initHexGridBuffers(std::vector<hex_info>* hexes);
void fillTriangleBufferFromHex(GLfloat buf[], int idx,  const hex_info &hex);
void fillColorBuffer(GLfloat buf[], int len, std::vector<hex_info>* hexes);
void fillHexLineBuffer(GLfloat buf[], int len, std::vector<hex_info>* hexes);

static render_state* g_render_state;


// interface

// TODO: maybe make this a contructor for render_state?
bool
initRenderer(render_state* rs)
{
	g_render_state = rs;

	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_FORWARD_COMPATIBLE_FLAG);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
	SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
	SDL_GetCurrentDisplayMode(0, &rs->handles.currentDisplayMode);
	rs->handles.window =
		SDL_CreateWindow("hexgame", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
							rs->viewport_dims.x, rs->viewport_dims.y, SDL_WINDOW_OPENGL|SDL_WINDOW_RESIZABLE);

	if (!rs->handles.window) {
		LOG(ERROR) << "Error creating window: " << SDL_GetError() << "\n";
		return false;
	}

	rs->handles.glContext = SDL_GL_CreateContext(rs->handles.window);

	if (!rs->handles.glContext) {
		LOG(ERROR) << "Error creating glContext: " << SDL_GetError() << "\n";
		return false;
	}

	if (SDL_GL_SetSwapInterval(1) != 0) {	// vsync
		LOG(ERROR) << "SDL Errors: " << SDL_GetError() << "\n";
		return false;
	}

	if (gl3wInit()) {
		LOG(ERROR) << "failed to initialize OpenGL\n";
		return false;
	}

	LOG(INFO) << "opengl vendor: " << glGetString(GL_VENDOR) << "\n";
	LOG(INFO)<< "opengl renderer: " << glGetString(GL_RENDERER) << "\n";
	LOG(INFO) << "opengl version: " << glGetString(GL_VERSION) << "\n";

	glEnable(GL_DEPTH_TEST);
	glEnable(GL_LINE_SMOOTH);
	glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
#if 0
	// TODO: blending messes up rendering with mesa on intel graphics 4000
	glEnable(GL_BLEND);
	glBlendEquation(GL_FUNC_ADD);
	glBlendFunc(GL_ONE, GL_SRC_ALPHA);
#endif

	// TODO: glDebugMessageCallback is only availabe  from >v4.3
	//  check and warn if context doesn't support this function here
	glEnable (GL_DEBUG_OUTPUT);
	glDebugMessageCallback((GLDEBUGPROC) openglDebugCallback, 0);
	// hide VRAM debug messages
	glDebugMessageControl(GL_DONT_CARE, 33361, GL_DONT_CARE, 0, 0, GL_FALSE);

	const char* vs_code = utilDumpTextFile(DEFAULT_VERTEX_SHADER_FILE);
	const char* fs_code = utilDumpTextFile(DEFAULT_FRAGMENT_SHADER_FILE);

	bool shader_error = !rgInitShaderProgram(rs->default_shader, vs_code, fs_code);

	utilSafeFree(vs_code);
	utilSafeFree(fs_code);

	rs->max_lights = MAX_LIGHTS;
	rs->lights = UTIL_ALLOC(rs->max_lights, rg_point_light);

	if (shader_error) {
		LOG(ERROR) << "Error initializing shader program\n";
		return false;
	}

	return true;
}

void
freeBuffers(render_state* rs)
{
	utilSafeFree(rs->lights);
	rgFree(rs->filled_hex_render_group);
	rgFree(rs->hex_line_render_group);
	rgFree(rs->debug_render_group);
}

bool
addTexture(SDL_Handles &handles, const char * path)
{
	// testing
	LOG(INFO) << "Loading image: " << path << "\n";
	SDL_Surface* image = IMG_Load(path);

	if (!image)
	{
		LOG(ERROR) << "IMG_Load: " << IMG_GetError() << "\n";
		return false;
	}

	GLuint tex_id;
	glGenTextures(1, &tex_id);
	glBindTexture(GL_TEXTURE_2D, tex_id);
	glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, image->w, image->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, image->pixels);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

	// store opengl id in SDL_Surface.userdat
	image->userdata = (void*)(intptr_t) tex_id;
	handles.texSurfaces.push_back(image);

	return true;
}

bool
createScene(render_state* rs, std::vector<hex_info>* hexes, Entity* entities, uint32 entity_count)
{
	// entities

	for (uint i = 0; i < entity_count; i++) {
		rgInitEntity(&entities[i]);
		entities[i].ren_group->shader = rs->default_shader;
	}

	if (!initHexGridBuffers(hexes))
		return false;

	// debug draw vertices

	uint debug_buf_len = 12; // 4 vertices, 3 floats per vertex
	rs->debug_render_group = rgInitSingle(rs->default_shader, debug_buf_len, true, 0, GL_LINE_LOOP);

	if (rs->debug_render_group == nullptr)
		return false;

	gl_buffer& debug_vertex_buf = rs->debug_render_group->render_objects[0]->vertex_buffer;
	gl_buffer& debug_color_buf = rs->debug_render_group->render_objects[0]->color_buffer;
	gl_buffer& debug_normal_buf = rs->debug_render_group->render_objects[0]->normal_buffer;

	for (uint i = 0; i < debug_buf_len; i += 3) {
		debug_color_buf.buffer[i] = 1.f;
		debug_color_buf.buffer[i + 1] = 0.f;
		debug_color_buf.buffer[i + 2] = 0.f;

		debug_normal_buf.buffer[i] = 0.f;
		debug_normal_buf.buffer[i + 1] = 0.f;
		debug_normal_buf.buffer[i + 2] = 1.f;
	}

	rgBufferData(&debug_vertex_buf, GL_DYNAMIC_DRAW, GL_ARRAY_BUFFER);
	rgBufferData(&debug_color_buf, GL_STATIC_DRAW, GL_ARRAY_BUFFER);
	rgBufferData(&debug_normal_buf, GL_STATIC_DRAW, GL_ARRAY_BUFFER);

	return true;
}

void
renderFrame(render_state* rs, std::vector<hex_info> *hexes, Entity* entities, uint32 entity_count)
{
	glClearColor(g_clear_col.R, g_clear_col.G, g_clear_col.B, g_clear_col.A);
	glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

	glm::mat4 m_model = g_render_state->cam.model;
	glm::mat4 m_view = g_render_state->cam.view;
	glm::mat4 m_projection = g_render_state->cam.projection;

	// filled hexes

	// get new colors every frame
	render_group* rg = rs->filled_hex_render_group;
	gl_buffer& color_buf = rg->render_objects[0]->color_buffer;
	// TODO: this needs optimization for large grids, very performance intensive
	fillColorBuffer(color_buf.buffer, color_buf.buffer_len, hexes);
	rgDraw(rg, m_model, m_view, m_projection,
		rs->lights, rs->num_lights, false, true);

	// hex lines
	rgDraw(rs->hex_line_render_group, m_model, m_view, m_projection,
			rs->lights, rs->num_lights);

	// entities
	for (uint i = 0; i < entity_count; i++) {
		rgDraw(entities[i].ren_group, entities[i].world_transform , m_view, m_projection,
			rs->lights, rs->num_lights);
	}
}

void
renderDebug(render_state* rs, std::vector<Point> &vertices)
{
	GLfloat* buf = rs->debug_render_group->render_objects[0]->vertex_buffer.buffer;
	buf[0] = vertices[0].x; buf[1] = vertices[0].y; buf[2] = 0;
	buf[3] = vertices[1].x; buf[4] = vertices[1].y; buf[2] = 0;
	buf[6] = vertices[2].x; buf[7] = vertices[2].y; buf[8] = 0;
	buf[9] = vertices[3].x; buf[10] = vertices[3].y; buf[11] = 0;

	rgDraw(rs->debug_render_group, g_render_state->cam.model, g_render_state->cam.view,
		g_render_state->cam.projection, rs->lights, rs->num_lights, true);
}


// internal

void
openglDebugCallback(GLenum source, GLenum type, GLuint id, GLenum severity,
					GLsizei length, const GLchar* message, const void* userParam)
{
	LOG((type == GL_DEBUG_TYPE_ERROR) ? ERROR : DEBUG)
		<< (type == GL_DEBUG_TYPE_ERROR ? "** GL ERROR **" : "")
		<< ", type: " << type
		<< ", severity: " << severity
		<< ", message: " << message << "\n";
}

// TODO: move hex logic to new file
bool
initHexGridBuffers(std::vector<hex_info>* hexes)
{
	// TODO: index duplicate vertices
	// 6 triangles * 3 vertices per triangle * 3 floats per vertex = 54
	uint line_vertices_per_hex = 6 * 2; // 12 vertices since we're using line segments atm
	uint line_buf_len = hexes->size() * line_vertices_per_hex * 3; // 3 floats per vertex
	uint vbuf_len = hexes->size() * 6 * 3 * 3;

	render_state* rs = g_render_state;
	rs->filled_hex_render_group = rgInitSingle(rs->default_shader, vbuf_len, true);

	if (rs->filled_hex_render_group == nullptr)
		return false;

	gl_buffer& vbuf = rs->filled_hex_render_group->render_objects[0]->vertex_buffer;
	gl_buffer& cbuf = rs->filled_hex_render_group->render_objects[0]->color_buffer;
	gl_buffer& normal_buf = rs->filled_hex_render_group->render_objects[0]->normal_buffer;

	for (uint i = 0; i < hexes->size(); i++)
		fillTriangleBufferFromHex(vbuf.buffer, i * 54, (*hexes)[i]);

	rgBufferData(&vbuf,	GL_DYNAMIC_DRAW, GL_ARRAY_BUFFER);
	fillColorBuffer(cbuf.buffer, vbuf_len, hexes);
	rgBufferData(&cbuf, GL_DYNAMIC_DRAW, GL_ARRAY_BUFFER);

	// cheat at vertex normals since all hexes lay flat on z-axis

	for (uint i = 0; i < vbuf_len; i += 3) {
		normal_buf.buffer[i] = 0.f;
		normal_buf.buffer[i + 1] = 0.f;
		normal_buf.buffer[i + 2] = 1.f;
	}
	rgBufferData(&normal_buf, GL_STATIC_DRAW, GL_ARRAY_BUFFER);

	// hex lines

	rs->hex_line_render_group = rgInitSingle(rs->default_shader, line_buf_len, true, 0, GL_LINES);

	if (rs->hex_line_render_group == nullptr)
		return false;

	gl_buffer& line_buf = rs->hex_line_render_group->render_objects[0]->vertex_buffer;
	gl_buffer& line_color_buf = rs->hex_line_render_group->render_objects[0]->color_buffer;
	gl_buffer& line_normal_buf = rs->hex_line_render_group->render_objects[0]->normal_buffer;
	fillHexLineBuffer(line_buf.buffer, line_buf_len, hexes);
	rgBufferData(&line_buf, GL_STATIC_DRAW, GL_ARRAY_BUFFER);

	for (uint i = 0; i < line_buf_len; i++)
		line_color_buf.buffer[i] = 0.f;

	rgBufferData(&line_color_buf, GL_STATIC_DRAW, GL_ARRAY_BUFFER);

	for (uint i = 0; i < line_buf_len; i += 3) {
		line_normal_buf.buffer[i] = 0.f;
		line_normal_buf.buffer[i + 1] = 0.f;
		line_normal_buf.buffer[i + 2] = 1.f;
	}

	rgBufferData(&line_normal_buf, GL_STATIC_DRAW, GL_ARRAY_BUFFER);

	return true;
}

void
fillTriangleBufferFromHex(GLfloat buf[], int idx,  const hex_info &hex)
{
	// triangles
	for (int i = 0; i < 6; i++)
	{
		// vertex 0
		buf[idx + 0] = (GLfloat) hex.XPos;
		buf[idx + 1] = (GLfloat) hex.YPos;
		buf[idx + 2] = (GLfloat) 0.f;

		// vertex 1
		buf[idx + 3] = (GLfloat) hex.vertices[i].x;
		buf[idx + 4] = (GLfloat) hex.vertices[i].y;
		buf[idx + 5] = (GLfloat) 0.f;

		if (i == 5)	// re-use the first point for the last triangle
		{
			// vertex 2
			buf[idx + 6] = (GLfloat) hex.vertices[0].x;
			buf[idx + 7] = (GLfloat) hex.vertices[0].y;
			buf[idx + 8] = (GLfloat) 0.f;
		}
		else
		{
			// vertex 2
			buf[idx + 6] = (GLfloat) hex.vertices[i + 1].x;
			buf[idx + 7] = (GLfloat) hex.vertices[i + 1].y;
			buf[idx + 8] = (GLfloat) 0.f;
		}

		// we've added 9 GLfloats per loop
		idx += 9;
	}
}

void
fillColorBuffer(GLfloat buf[], int len, std::vector<hex_info>* hexes)
{
	int buf_idx;
	int buf_len_per_hex = 54; // NOTE: 3 * 3 * 6
	GLfloat color_buf[3];
	for (int i = 0; i < (int) hexes->size(); i++)
	{
		buf_idx = i * buf_len_per_hex;
		hex_info hxi = (*hexes)[i];
		// TODO: check performance of this since we call multiple times per frame
		// 	maybe can cache glfloat triplets somewhere
		utilConvertColor(color_buf, hxi.current_color);

		for (int j = 0; j < buf_len_per_hex; j+=3)
		{
			buf[buf_idx + j] = color_buf[0];
			buf[buf_idx + j + 1] = color_buf[1];
			buf[buf_idx + j + 2] = color_buf[2];
		}
	}
}

void
fillHexLineBuffer(GLfloat buf[], int len, std::vector<hex_info>* hexes)
{
	Point p1, p2;
	int idx = 0;
	for (int i = 0; i < (int) hexes->size(); i++)
	{
		hex_info hxi = (*hexes)[i];
		for (int j = 0; j < 6; j ++)
		{
			if (j == 5) // wrap
			{
				p1 = hxi.vertices[j];
				p2 = hxi.vertices[0];
			}
			else
			{
				p1 = hxi.vertices[j];
				p2 = hxi.vertices[j + 1];
			}

			buf[idx + 0] = p1.x;
			buf[idx + 1] = p1.y;
			buf[idx + 2] = 0.f;
			buf[idx + 3] = p2.x;
			buf[idx + 4] = p2.y;
			buf[idx + 5] = 0.f;
			idx += 6;
		}
	}
}