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screenspace uv

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Rakarake 2025-12-08 18:48:31 +01:00
parent 56070f31e4
commit c118d92fa7
1 changed files with 50 additions and 81 deletions
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127
main.c
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@ -2,77 +2,8 @@
#include <stdio.h>
#include <GL/gl.h>
#include <GL/glext.h>
#include <SDL3/SDL.h>
float tanf(float in) {
return in;
}
void perspective(float fovY, float aspect, float zNear, float zFar, float* matrix) {
float f = 1.0f / tanf(fovY * 0.5f * (3.14159265358979323846f / 180.0f));
matrix[0] = f / aspect;
matrix[1] = 0;
matrix[2] = 0;
matrix[3] = 0;
matrix[4] = 0;
matrix[5] = f;
matrix[6] = 0;
matrix[7] = 0;
matrix[8] = 0;
matrix[9] = 0;
matrix[10] = (zFar + zNear) / (zNear - zFar);
matrix[11] = -1;
matrix[12] = 0;
matrix[13] = 0;
matrix[14] = (2 * zFar * zNear) / (zNear - zFar);
matrix[15] = 0;
}
void drawCube() {
glBegin(GL_QUADS);
// Back
glColor3f(0, 1, 0);
glVertex3f(-1, -1, -1);
glVertex3f(-1, 1, -1);
glVertex3f( 1, 1, -1);
glVertex3f( 1, -1, -1);
// Top
glColor3f(0, 0, 1);
glVertex3f(-1, 1, -1);
glVertex3f(-1, 1, 1);
glVertex3f( 1, 1, 1);
glVertex3f( 1, 1, -1);
// Bottom
glColor3f(1, 1, 0);
glVertex3f(-1, -1, -1);
glVertex3f( 1, -1, -1);
glVertex3f( 1, -1, 1);
glVertex3f(-1, -1, 1);
// Right
glColor3f(1, 0, 1);
glVertex3f(1, -1, -1);
glVertex3f(1, 1, -1);
glVertex3f(1, 1, 1);
glVertex3f(1, -1, 1);
// Left
glColor3f(0, 1, 1);
glVertex3f(-1, -1, -1);
glVertex3f(-1, -1, 1);
glVertex3f(-1, 1, 1);
glVertex3f(-1, 1, -1);
glEnd();
}
void checkGlError() {
const char *err = SDL_GetError();
if (*err != 0) {
@ -80,13 +11,47 @@ void checkGlError() {
}
}
const char *vertex_shader_source = "";
const char *fragment_shader_source =
"#version 330 core\n"
"out vec4 FragColor;\n"
"in vec2 uv;\n"
"\n"
"void main()\n"
"{\n"
" FragColor = vec4(gl_FragCoord.xy / 800, 0.0, 1.0);\n"
"}\n";
GLuint create_shader() {
GLuint vshader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vshader, 1, &vertex_shader_source, NULL); // vertex_shader_source is a GLchar* containing glsl shader source code
glCompileShader(vshader);
return vshader;
GLuint compile_shader(GLuint type, const char *src) {
GLuint id = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(id, 1, &src, 0);
glCompileShader(id);
int result;
glGetShaderiv(id, GL_COMPILE_STATUS, &result);
if (result == GL_FALSE) {
int length;
glGetShaderiv(id, GL_INFO_LOG_LENGTH, &result);
char *message = alloca(length * sizeof(char));
glGetShaderInfoLog(id, length, &length, message);
printf("failed to compile %s shader\n", type == GL_VERTEX_SHADER ? "vertex" : "fragment");
printf("%s\n", message);
glDeleteShader(id);
return 0;
}
return id;
}
GLuint create_shader(const char *fragment_src) {
GLuint program = glCreateProgram();
GLuint fragment_shader = compile_shader(GL_FRAGMENT_SHADER, fragment_src);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
glValidateProgram(program);
glDeleteShader(fragment_shader);
return program;
}
int main() {
@ -112,6 +77,10 @@ int main() {
SDL_Event e;
int running = 1;
float angle = 0.0;
GLuint shader = create_shader(fragment_shader_source);
glUseProgram(shader);
while (running) {
while (SDL_PollEvent(&e)) {
if (e.type == SDL_EVENT_QUIT) running = false;
@ -119,18 +88,18 @@ int main() {
checkGlError();
// Rendorrrr
glViewport(0, 0, 800, 600);
glViewport(0, 0, 800, 800);
glClearColor(0.1f, 0.1f, 0.1f, 1.0f); // Dark gray background
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//drawCube();
// Front
glBegin(GL_QUADS);
glColor3f(1, 0, 0);
glVertex2f(-1, -1);
glVertex2f(-1, 1);
glVertex2f( 1, 1);
glVertex2f(-1,-1);
glVertex2f( 1,-1);
glVertex2f( 1, 1);
glEnd();
SDL_GL_SwapWindow(window);