1 files changed, 191 insertions, 0 deletions
diff --git a/glgfx.cpp b/glgfx.cpp
new file mode 100644
index 0000000..6700601
--- /dev/null
+++ b/glgfx.cpp
@@ -0,0 +1,191 @@
+#include "glgfx.h"
+//buffer handles are the ints that gl returns
+//buffer data is the data you bind to opengl
+GLuint vbhandler; //vertex buffer handle
+GLuint ebhandler;
+//handlers for the perspective transforms
+GLint projhandler;
+GLint tranhandler;
+GLint camhandler;
+glm::mat4 tran;
+//device coordinates
+//      ^
+//    (y+)
+//      |
+//<(x-)-+-(x+)>
+//      |
+//    (y-)
+//      v
+//shaders
+// z+ is close to screen z- is farther away
+GLuint vertexshaderhandle;
+GLuint fragmentshaderhandle;
+GLuint shaderprogramhandle;
+int initglgfx() {
+	//glew is the library that links all of opengl's fnctions
+	//for you
+	glewExperimental = GL_TRUE;
+	glewInit();
+	glEnable (GL_BLEND);
+	// so we can have transparent polygons
+	glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);	
+	//culls back face triagnles, which is determined by whether vertexes are clockwise
+	// or counterclockwise
+	glEnable(GL_CULL_FACE);
+	glCullFace(GL_BACK);
+	GLuint glnum;
+	glGenBuffers(1, &glnum);
+	printf("%u\n",glnum);
+	//vertex data load of the box model
+	float vertexdata[] = {
+		-0.5, 0.5, -.5, // x y z
+		0.5, 0.5, -.5,
+		0.5, -0.5, -.5,
+		-0.5, -0.5, -.5,
+		-0.5, 0.5, 0.5, // x y z
+		0.5, 0.5, 0.5,
+		0.5, -0.5, 0.5,
+		-0.5, -0.5, 0.5
+	};
+	//polygons of the box mode based on the vertex data.
+	//they must be clockwise from the front so that they are culled when not
+	//seen
+	GLuint elementdata[] = {
+		0,1,3,
+		3,1,2,
+		1,5,2,
+		2,5,6,
+		5,4,6,
+		4,7,6,
+		4,0,7,
+		0,3,7,
+		3,6,7,
+		2,6,3,
+		0,4,5,
+		5,1,0,
+	};
+	//binds to the element buffer
+	glGenBuffers(1,&vbhandler);
+	glBindBuffer(GL_ARRAY_BUFFER,vbhandler);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(vertexdata), vertexdata, GL_DYNAMIC_DRAW);
+	glGenBuffers(1,&ebhandler);
+	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,ebhandler);
+	glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(elementdata), elementdata, GL_DYNAMIC_DRAW);
+	//loads the shaders
+	genshaders();
+	
+}
+//loads shaders and models
+int genshaders() {
+//flowchart
+//vertex shader receives raw vertex data, outputs that data transformed in 3d space(camera), that data is passed to
+//geometry shader, which is where we will add normal vector for
+//light calculations // also where we make the volumetric information
+//all these are rasterized, and blended for every pixel value
+//then passed to fragment shader
+//which is where we do the light calculations
+//tests and blending(multiple buffers?)
+	//reads from files
+	//debug printout
+	//printf(readfile("vertexshader.glsl").c_str());
+	std::string vertexshadersource = readfile("vertexshader.glsl").c_str();
+	std::string fragmentshadersource = readfile("fragmentshader.glsl").c_str();
+	const char * vertexshaderstr = vertexshadersource.c_str();
+	const char * fragmentshaderstr = fragmentshadersource.c_str();
+	GLuint vertexshaderhandle = glCreateShader(GL_VERTEX_SHADER);
+	int vertexshaderlen = vertexshadersource.length();
+	//length of the source must be specified
+	glShaderSource(vertexshaderhandle, 1, (&vertexshaderstr), &vertexshaderlen);
+	glCompileShader(vertexshaderhandle);
+	//error buffer
+	char buffer[512];
+	GLint err;
+	glGetShaderiv(vertexshaderhandle, GL_COMPILE_STATUS, &err);
+	if (err == GL_FALSE) {
+		glGetShaderInfoLog(vertexshaderhandle, 512, NULL, buffer);
+		printf("error compiling vertex shhader\n");
+		printf(buffer);
+	}
+	
+	GLuint fragmentshaderhandle = glCreateShader(GL_FRAGMENT_SHADER);
+	int fragmentshaderlen = fragmentshadersource.length();
+	//the length of the source must be specified
+	glShaderSource(fragmentshaderhandle, 1, (&fragmentshaderstr), &fragmentshaderlen);
+	glCompileShader(fragmentshaderhandle);
+	glGetShaderiv(fragmentshaderhandle, GL_COMPILE_STATUS, &err);
+	if (err == GL_FALSE) {
+		glGetShaderInfoLog(fragmentshaderhandle, 512, NULL, buffer);
+		printf("error compiling fragment shader\n");
+		printf(buffer);
+	}
+	//make the shader program
+	shaderprogramhandle = glCreateProgram();
+	glAttachShader(shaderprogramhandle,vertexshaderhandle);
+	glAttachShader(shaderprogramhandle,fragmentshaderhandle);
+	//the 0 is which buffer, 0 is the default, 1 will be fore volumetric shading
+	glBindFragDataLocation(shaderprogramhandle,0,"outpix");
+	glLinkProgram(shaderprogramhandle);
+	glUseProgram(shaderprogramhandle);
+	//vertex data
+	GLint pos;
+	pos = glGetAttribLocation(shaderprogramhandle, "position");
+	//the actual atribute, number of values, type, whether they need to be normalied to -1 1,
+	//number of bytes between values, offset from beginning in bytes
+	glVertexAttribPointer(pos, 3, GL_FLOAT, GL_FALSE, 0, 0);
+	glEnableVertexAttribArray(pos);
+
+}
+//opens a filebuffer stream and reads every char
+std::string readfile(char const * filename) {
+	std::ifstream filebuffer;
+	std::string line;
+	std::string rstr;
+	rstr = "";
+	char c;
+	filebuffer.open(filename);
+	if (!filebuffer.is_open()) {
+		printf("error reading file");
+	}
+	while (filebuffer.get(c)) {
+		rstr = rstr + c;
+	}
+	filebuffer.close();
+	return rstr;
+}
+//draws the model, setting perspective transform and position transform
+//done with magic numbers for now for testing purposes
+int drawmodel(float x, float y, float z, float xr, float yr, float zr) {
+// the transformation matrix = rotation matrix of object * scaling matrix * translaton matrix representing difference in camera and object location * -rotation matrix of the camera * perspective transform
+//order of application ir right to left
+	//fov, aspect ratio, size of near and far planes distance
+	glm::mat4 proj = glm::perspective(glm::radians(45.0f), (float)maxx/(float)maxy, 0.1f, 100.0f);
+	projhandler = glGetUniformLocation(shaderprogramhandle, "proj");
+	glUniformMatrix4fv(projhandler, 1, GL_FALSE, glm::value_ptr(proj));
+	//lookat eye position of camera, center center of screen, up up direction
+	glm::mat4 cam = glm::lookAt(glm::vec3(0,0,1), glm::vec3(0,0,0),glm::vec3(0,1,0));
+	camhandler = glGetUniformLocation(shaderprogramhandle, "cam");
+	glUniformMatrix4fv(camhandler, 1, GL_FALSE, glm::value_ptr(cam));
+	//a valid tranlation matrix showing the colun first conventions of glm::mat4
+	//tran = glm::mat4(
+	//	glm::vec4(1.0f,0.0f,0.0f,0.0f), //x transform is the one on the last column
+	//	glm::vec4(0.0f,1.0f,0.0f,0.0f), //y
+	//	glm::vec4(0.0f,0.0f,1.0f,0.0f), // z
+	//	glm::vec4(0.0f,0.0f,0.5f,1.0f)  //w just make it 1
+	//);
+	//the translation matrix, matrixes added last are applied first
+	glm::mat4 tran;
+	tran = glm::translate(tran, glm::vec3(x,y,z));
+	tran = glm::rotate(tran,glm::radians(xr),glm::vec3(1,0,0)); // axis of rotation x y z
+	tran = glm::rotate(tran,glm::radians(yr),glm::vec3(0,1,0));
+	tran = glm::rotate(tran,glm::radians(zr),glm::vec3(0,0,1));
+	//deprecated debug stuff
+	//printf("translated vector x%f\n",(tran * glm::vec4(0.0f,0.0f,0.0f,1.0f)).x);
+	//printf("translated vector y%f\n",(tran * glm::vec4(0.0f,0.0f,0.0f,1.0f)).y);
+	//printf("translated vector z%f\n",(tran * glm::vec4(0.0f,0.0f,0.0f,1.0f)).z);
+	//loads the transaltion stuff
+	tranhandler = glGetUniformLocation(shaderprogramhandle, "tran");
+	glUniformMatrix4fv(tranhandler, 1, GL_FALSE, glm::value_ptr(tran));
+	glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);
+}
+int quitglgfx() {
+}