5.1. TransformationsΒΆ
Open a window and type in the following code:
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <iostream>
#include <SOIL.h>
#define GLM_FORCE_RADIANS
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include "Shader.h"
GLfloat mix_value=0.2f;
void key_callback(GLFWwindow* window,int key,int scancode,int action,int mode)
{
if(key==GLFW_KEY_ESCAPE && action==GLFW_PRESS)
glfwSetWindowShouldClose(window,GL_TRUE);
if(key==GLFW_KEY_UP && action==GLFW_PRESS)
{
mix_value+=0.1f;
if(mix_value>1.0f) mix_value=1.0f;
}
if(key==GLFW_KEY_DOWN && action==GLFW_PRESS)
{
mix_value-=0.1f;
if(mix_value<0.0f) mix_value=0.0f;
}
}
int main()
{
glfwInit();
#if __APPLE__
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT,GL_TRUE);
#endif
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR,3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR,3);
glfwWindowHint(GLFW_OPENGL_PROFILE,GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_RESIZABLE,GL_FALSE);
GLFWwindow *window=glfwCreateWindow(800,600,"Learn OpenGL",nullptr,nullptr);
if(window==nullptr)
{
std::cout<<"Failed to create GLFW window!"<<std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glewExperimental=GL_TRUE;
if(glewInit()!=GLEW_OK)
{
std::cout<<"Failed to initialize GLEW!"<<std::endl;
return -1;
}
int width,height;
glfwGetFramebufferSize(window,&width,&height);
glViewport(0,0,width,height);
glfwSetKeyCallback(window,key_callback);
Shader our_shader("shader.vs","shader.frag");
GLuint texture1,texture2;
// generate texture 1
glGenTextures(1,&texture1);
glBindTexture(GL_TEXTURE_2D,texture1);
// set texture parameters
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP_TO_EDGE);
// set texture filtering
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
// load, create and generate mipmaps
unsigned char* image=SOIL_load_image("container.jpg",&width,&height,0,SOIL_LOAD_RGB);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,width,height,0,GL_RGB,GL_UNSIGNED_BYTE,image);
glGenerateMipmap(GL_TEXTURE_2D);
// free image data
SOIL_free_image_data(image);
glBindTexture(GL_TEXTURE_2D,0);
// generate texture 2
glGenTextures(1,&texture2);
glBindTexture(GL_TEXTURE_2D,texture2);
// set texture parameters
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_REPEAT);
// set texture filtering
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);
// load, create and generate mipmaps
image=SOIL_load_image("awesomeface.png",&width,&height,0,SOIL_LOAD_RGB);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGB,width,height,0,GL_RGB,GL_UNSIGNED_BYTE,image);
glGenerateMipmap(GL_TEXTURE_2D);
// free image data
SOIL_free_image_data(image);
glBindTexture(GL_TEXTURE_2D,0);
GLfloat vertices[]={
// positions // colors // textures
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f,
0.5f,-0.5f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f,
-0.5f,-0.5f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
-0.5f, 0.5f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f
};
GLuint indices[]={
0, 1, 3,
1, 2, 3
};
GLuint VAO,VBO,EBO;
glGenBuffers(1,&VBO);
glGenBuffers(1,&EBO);
glGenVertexArrays(1,&VAO);
// bind vertex array object
glBindVertexArray(VAO);
// copy the vertices in a buffer
glBindBuffer(GL_ARRAY_BUFFER,VBO);
glBufferData(GL_ARRAY_BUFFER,sizeof(vertices),vertices,GL_STATIC_DRAW);
// copy the index array in an element buffer
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER,EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER,sizeof(indices),indices,GL_STATIC_DRAW);
// set position attribute pointers
glVertexAttribPointer(0,3,GL_FLOAT,GL_FALSE,8*sizeof(GL_FLOAT),(GLvoid*)0);
glEnableVertexAttribArray(0);
// set color attribute pointers
glVertexAttribPointer(1,3,GL_FLOAT,GL_FALSE,8*sizeof(GL_FLOAT),(GLvoid*)(3*sizeof(GLfloat)));
glEnableVertexAttribArray(1);
// set texture attribute pointers
glVertexAttribPointer(2,2,GL_FLOAT,GL_FALSE,8*sizeof(GL_FLOAT),(GLvoid*)(6*sizeof(GLfloat)));
glEnableVertexAttribArray(2);
// unbind the vertex array object
glBindVertexArray(0);
while(!glfwWindowShouldClose(window))
{
glfwPollEvents();
glClearColor(.2f,.3f,.3f,1.f);
glClear(GL_COLOR_BUFFER_BIT);
// use shader program
our_shader.Use();
// bind textures
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,texture1);
glUniform1i(glGetUniformLocation(our_shader.program,"our_texture1"),0);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D,texture2);
glUniform1i(glGetUniformLocation(our_shader.program,"our_texture2"),1);
glUniform1f(glGetUniformLocation(our_shader.program,"mix_value"),mix_value);
// generate transformation matrix
glm::mat4 trans(1.0f);
trans=glm::translate(trans,glm::vec3(0.5f,-0.5f,0.0f));
trans=glm::rotate(trans,glm::radians((GLfloat)glfwGetTime()*50.0f),glm::vec3(0.0f,0.0f,1.0f));
GLuint transform_location=glGetUniformLocation(our_shader.program,"transform");
glUniformMatrix4fv(transform_location,1,GL_FALSE,glm::value_ptr(trans));
// draw
glBindVertexArray(VAO);
glDrawElements(GL_TRIANGLES,6,GL_UNSIGNED_INT,0);
glBindVertexArray(0);
glfwSwapBuffers(window);
}
// deallocate all resources
glDeleteVertexArrays(1,&VAO);
glDeleteBuffers(1,&VBO);
glDeleteBuffers(1,&EBO);
// terminate GLFW
glfwTerminate();
return 0;
}
Save this file as main.cpp. Open another window and type in the following
code:
#version 330 core
layout (location=0) in vec3 position;
layout (location=1) in vec3 color;
layout (location=2) in vec2 tex_coord;
out vec3 our_color;
out vec2 TexCoord;
uniform mat4 transform;
void main()
{
gl_Position=transform*vec4(position,1.0f);
our_color=color;
TexCoord=vec2(tex_coord.x,1.0f-tex_coord.y);
}
Save this file as shader.vs. Finally, open another window and type the
following code:
#version 330 core
in vec3 our_color;
in vec2 TexCoord;
out vec4 color;
uniform float mix_value;
uniform sampler2D our_texture1;
uniform sampler2D our_texture2;
void main()
{
color=mix(texture(our_texture1,TexCoord),texture(our_texture2,TexCoord),mix_value);
}
Save this file as shader.frag.