Reputation: 175
I am trying to render a 2D square that has color and is transformed due to 4x4 matrices. The output is supposed to look like this:
However, I am instead getting this:
This is frustrating because I had this problem in another project. My professor walked me through how to solve it and all we did was play around with a few things here and there and it just magically worked, no code was altered. Now I am experiencing this issue again and there are no clues as to why this is happening. I typed the tutorial code correctly character for character and it is not being rendered correctly. It did however render correctly on my professor's computer.
Here is the code:
#include <GL/glew.h>
#include <GL/freeglut.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <iostream>
#define WINDOW_TITLE "Modern OpenGL"
#ifndef GLSL
#define GLSL(Version, Source) "#version" #Version "\n" #Source
#endif
GLint shaderProgram, windowWidth = 800, windowHeight = 600;
GLuint VBO, VAO, EBO, texture;
void uResizeWindow(int, int);
void uRenderGraphics();
void uCreateShader();
void uCreateBuffers();
//Vertex shader source code
const GLchar* vertexShaderSource = GLSL(330,
layout(location = 0) in vec3 position;
layout(location = 1) in vec3 color;
out vec3 mobileColor;
uniform mat4 model;
uniform mat4 view;
uniform mat4 projection;
void main() {
gl_Position = projection * view * model * vec4(position, 1.0f); //transforms vertices to clip coordinates
mobileColor = color; //references incoming color data
});
//Fragment shader source code
const GLchar* fragmentShaderSource = GLSL(330,
in vec3 mobileColor;
out vec4 gpuColor;
void main() {
gpuColor = vec4(mobileColor, 1.0f);
});
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize(windowWidth, windowHeight);
glutCreateWindow(WINDOW_TITLE);
glutReshapeFunc(uResizeWindow);
glewExperimental = GL_TRUE;
if (glewInit() != GLEW_OK) {
std::cout << "Failed to initialize GLEW" << std::endl;
}
uCreateShader();
uCreateBuffers();
glUseProgram(shaderProgram);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glutDisplayFunc(uRenderGraphics);
glutMainLoop();
//Destroys buffer objects once used
glDeleteVertexArrays(1, &VAO);
glDeleteBuffers(1, &VBO);
glDeleteBuffers(1, &EBO);
return 0;
}
void uResizeWindow(int w, int h) {
windowWidth = w;
windowHeight = h;
glViewport(0, 0, windowWidth, windowHeight);
}
void uRenderGraphics() {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBindVertexArray(VAO);
glm::mat4 model(1.0f);
model = glm::translate(model, glm::vec3(0.0f, 0.0f, 0.0f)); //place object at center of viewport
model = glm::rotate(model, 15.0f, glm::vec3(1.0f, 0.0f, 0.0f)); //rotate object 15 degrees on x-axis
model = glm::scale(model, glm::vec3(2.0f, 2.0f, 2.0f)); //increase object size by factor of 2
//transforms the camera
glm::mat4 view(1.0f);
view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f)); //moves camera backwards -3 units in z
//creates perspective projection
glm::mat4 projection(1.0f);
projection = glm::perspective(45.0f, (GLfloat)windowWidth / (GLfloat)windowHeight, 0.1f, 100.0f);
//retrieves and passes transform matrices to shader program
GLint modelLoc = glGetUniformLocation(shaderProgram, "model");
GLint viewLoc = glGetUniformLocation(shaderProgram, "view");
GLint projLoc = glGetUniformLocation(shaderProgram, "projection");
//draws the triangles
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
glBindVertexArray(0); //deactive the vertex array object
glutSwapBuffers();
}
void uCreateShader() {
//vertex
GLint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
//fragment
GLint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
}
void uCreateBuffers() {
GLfloat vertices[] = {
0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 0.0f, //top right vertex 0
0.5f, -0.5f, 0.0f, 0.0f, 1.0f, 0.0f, //bottom right vertex 1
-0.5f, -0.5f, 0.0f, 0.0f, 0.0f, 1.0f, //bottom left vertex 2
-0.5f, 0.5f, 0.0f, 1.0f, 0.0f, 1.0f //top left vertex 3
};
GLuint indices[] = {
0, 1, 3, //triangle 1
1, 2, 3 //triangle 2
};
//gen buffer ids
glGenVertexArrays(1, &VAO);
glGenBuffers(1, &VBO);
glGenBuffers(1, &EBO);
glBindVertexArray(VAO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
//set attrib pointer 0 to hold pos data
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)0);
glEnableVertexAttribArray(0);
//set attrib pointer 1 to hold color data
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
glEnableVertexAttribArray(1);
glBindVertexArray(0); //deactivate VAO
}
Upvotes: 1
Views: 676
Reputation: 210877
The vertex shader and the fragment shader cannot be compiled because a space is missing in the GLSL macro (after #version
):
#define GLSL(Version, Source) "#version" #Version "\n" #Source
#define GLSL(Version, Source) "#version " #Version "\n" #Source
I recommend to check if the shader compilation succeeded and if the program object linked successfully.
If the compiling of a shader succeeded can be checked by glGetShaderiv
and the parameter GL_COMPILE_STATUS
. If the linking of a program was successful can be checked by glGetProgramiv
and the parameter GL_LINK_STATUS
.
See the answer to OpenGL ignores Quads and makes them Triangles.
The unit of the angle argument of glm::perspective
is radian:
projection = glm::perspective(45.0f, (GLfloat)windowWidth / (GLfloat)windowHeight, 0.1f, 100.0f);
projection = glm::perspective(glm::radians(45.0f),
(GLfloat)windowWidth / (GLfloat)windowHeight, 0.1f, 100.0f);
You missed to set the matrix uniforms:
GLint modelLoc = glGetUniformLocation(shaderProgram, "model");
GLint viewLoc = glGetUniformLocation(shaderProgram, "view");
GLint projLoc = glGetUniformLocation(shaderProgram, "projection");
glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));
Upvotes: 1