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#include <gsr/plugin.h>
#include <stddef.h>
#include <stdlib.h>
#include <math.h>
#define GL_GLEXT_PROTOTYPES
#include <GL/gl.h>
const char vertex_shader_source[] =
"attribute vec4 vertex_pos; \n"
"void main() { \n"
" gl_Position = vertex_pos; \n"
"}";
const char fragment_shader_source[] =
"precision mediump float; \n"
"uniform vec3 color; \n"
"void main() { \n"
" gl_FragColor = vec4(color, 1.0); \n"
"}";
typedef struct {
GLuint shader_program;
GLuint vao;
GLuint vbo;
GLint color_uniform;
unsigned int counter;
} Triangle;
static GLuint load_shader(const char *shaderSrc, GLenum type) {
GLuint shader = glCreateShader(type);
glShaderSource(shader, 1, &shaderSrc, NULL);
glCompileShader(shader);
return shader;
}
static void draw(const gsr_plugin_draw_params *params, void *userdata) {
Triangle *triangle = userdata;
GLfloat glverts[6];
glverts[0] = -0.5f;
glverts[1] = -0.5f;
glverts[2] = 0.5f;
glverts[3] = -0.5f;
glverts[4] = 0.0f;
glverts[5] = 0.5f;
glBindVertexArray(triangle->vao);
glBindBuffer(GL_ARRAY_BUFFER, triangle->vbo);
glBufferSubData(GL_ARRAY_BUFFER, 0, 6 * sizeof(float), glverts);
glUseProgram(triangle->shader_program);
const double pp = triangle->counter * 0.05;
glUniform3f(triangle->color_uniform, 0.5 + sin(pp)*0.5, 0.5 + cos(pp)*0.5, 0.5 + sin(0.2 + pp)*0.5);
glDrawArrays(GL_TRIANGLES, 0, 3);
glBindVertexArray(0);
glUseProgram(0);
++triangle->counter;
}
bool gsr_plugin_init(const gsr_plugin_init_params *params, gsr_plugin_init_return *ret) {
Triangle *triangle = calloc(1, sizeof(Triangle));
if(!triangle)
return false;
triangle->shader_program = glCreateProgram();
const GLuint vertex_shader = load_shader(vertex_shader_source, GL_VERTEX_SHADER);
const GLuint fragment_shader = load_shader(fragment_shader_source, GL_FRAGMENT_SHADER);
glAttachShader(triangle->shader_program, vertex_shader);
glAttachShader(triangle->shader_program, fragment_shader);
glBindAttribLocation(triangle->shader_program, 0, "vertex_pos");
glLinkProgram(triangle->shader_program);
glGenVertexArrays(1, &triangle->vao);
glBindVertexArray(triangle->vao);
glGenBuffers(1, &triangle->vbo);
glBindBuffer(GL_ARRAY_BUFFER, triangle->vbo);
glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), NULL, GL_DYNAMIC_DRAW);
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void *)0);
glBindVertexArray(0);
glDeleteShader(vertex_shader);
glDeleteShader(fragment_shader);
triangle->color_uniform = glGetUniformLocation(triangle->shader_program, "color");
ret->name = "hello_triangle";
ret->version = 1;
ret->userdata = triangle;
ret->draw = draw;
return true;
}
void gsr_plugin_deinit(void *userdata) {
Triangle *triangle = userdata;
glDeleteProgram(triangle->shader_program);
free(triangle);
}
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