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factor out init functions

This commit is contained in:
ktyl 2021-07-09 01:00:19 +01:00
parent 9e004cdb5b
commit 5082b4abc7
3 changed files with 83 additions and 78 deletions
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76
src/gfx.c
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@ -1,8 +1,22 @@
#include "gfx.h"
#include "stb_image.h"
const char* vertShaderPath = "res/shader/shader.vert";
const char* fragShaderPath = "res/shader/shader.frag";
float vertices[] = {
// position color uvs
1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right
1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right
-1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left
-1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left
};
unsigned int indices[] = {
0, 1, 3,
1, 2, 3
};
SDL_Window* sdlWindow;
SDL_GLContext* sdlContext;
@ -99,3 +113,65 @@ GLuint compileShader(const char* path, GLenum type)
return shader;
}
void setVertexAttributes()
{
int stride = 8*sizeof(float);
// position
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, stride, (void*)0);
glEnableVertexAttribArray(0);
// color
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, (void*)(3*sizeof(float)));
glEnableVertexAttribArray(1);
// uv
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, stride, (void*)(6*sizeof(float)));
glEnableVertexAttribArray(2);
}
void createTextureFromFile()
{
// create an opengl texture and bind it to the GL_TEXTURE_2D target
unsigned int texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_REPEAT);
// load image data from file
const char* imagePath = "res/tex.png";
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(1);
unsigned char* data = stbi_load(imagePath, &width, &height, &nrChannels, 0);
if (!data)
{
fputs("failed to load texture data: ", stderr);
fputs(imagePath, stderr);
fputs("\n", stderr);
exit(1);
}
// read image data into bound opengl texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
stbi_image_free(data);
}
void initBuffers()
{
unsigned int VAO, VBO, EBO;
glGenVertexArrays(1, &VAO); // vertex array object
glGenBuffers(1, &VBO); // vertex buffer object
glGenBuffers(1, &EBO); // element buffer object
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);
}

4
src/gfx.h
View File

@ -13,3 +13,7 @@ SDL_Window* gfxInit();
unsigned int compileShaderProgram();
void createTextureFromFile();
void setVertexAttributes();
void initBuffers();

81
src/main.c
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@ -1,20 +1,6 @@
#include "main.h"
#include "gfx.h"
#include "stb_image.h"
float vertices[] = {
// position color uvs
1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, // top right
1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f, // bottom right
-1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, // bottom left
-1.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f // top left
};
unsigned int indices[] = {
0, 1, 3,
1, 2, 3
};
// forward declarations
@ -28,68 +14,13 @@ int main()
{
SDL_Window* window = gfxInit();
// generate opengl texture
unsigned int texture;
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
createTextureFromFile();
// load image data from file
const char* imageFile = "res/tex.png";
int width, height, nrChannels;
stbi_set_flip_vertically_on_load(1);
unsigned char* data = stbi_load(imageFile, &width, &height, &nrChannels, 0);
if (!data)
{
fputs("failed to load texture data: ", stderr);
fputs(imageFile, stderr);
fputs("\n", stderr);
exit(1);
}
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
glGenerateMipmap(GL_TEXTURE_2D);
initBuffers();
// free loaded image data
stbi_image_free(data);
setVertexAttributes();
unsigned int shaderProgram = compileShaderProgram();
// vertex array object
unsigned int VAO;
glGenVertexArrays(1, &VAO);
// vertex buffer object
unsigned int VBO;
glGenBuffers(1, &VBO);
// element buffer object
unsigned int EBO;
glGenBuffers(1, &EBO);
glBindVertexArray(VAO);
// copy our vertices into a buffer opengl can use
glBindBuffer(GL_ARRAY_BUFFER, VBO); // bind it to the GL_ARRAY_BUFFER target
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW); // copy user-defined data into currently bound buffer
// copy indices into a buffer for opengl
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
// set vertex attributes
int stride = 8*sizeof(float);
// position attribute
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, stride, (void*)0); // TODO: wtf
glEnableVertexAttribArray(0);
// color attribute
glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, stride, (void*)(3 * sizeof(float)));
glEnableVertexAttribArray(1);
// uv attribute
glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, stride, (void*)(6 * sizeof(float)));
glEnableVertexAttribArray(2);
glUseProgram(shaderProgram);
// render loop
@ -99,12 +30,6 @@ int main()
glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
// update uniforms
//float time = (float)SDL_GetTicks() / 1000.0f;
//float greenValue = (sin(time)/2.0f)+0.5f;
//int vertexColorLocation = glGetUniformLocation(shaderProgram, "ourColor");
//glUniform4f(vertexColorLocation, 0.0f, greenValue, 0.0f, 1.0f);
// draw
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
SDL_GL_SwapWindow(window);