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background_gl.c
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background_gl.c
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/*
The MIT License (MIT)
Copyright (c) 2014 Adam Simpson
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include "fluid.h"
#include "renderer.h"
#include "lodepng.h"
#include "background_gl.h"
#include "ogl_utils.h"
void create_backround_program(background_t *state)
{
// Compile vertex shader
GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
#ifdef RASPI
compile_shader(vertex_shader, "SPH/shaders/background_es.vert");
#else
compile_shader(vertex_shader, "shaders/background.vert");
#endif
// Compile fragment shader
GLuint frag_shader = glCreateShader(GL_FRAGMENT_SHADER);
#ifdef RASPI
compile_shader(frag_shader, "SPH/shaders/background_es.frag");
#else
compile_shader(frag_shader, "shaders/background.frag");
#endif
// Create shader program
state->program = glCreateProgram();
glAttachShader(state->program, vertex_shader);
glAttachShader(state->program, frag_shader);
// Link program
glLinkProgram(state->program);
show_program_log(state->program);
// Get position attribute location
state->position_location = glGetAttribLocation(state->program, "position");
// Get tex_coord location
state->tex_coord_location = glGetAttribLocation(state->program, "tex_coord");
// Get tex uniform location
state->tex_location = glGetUniformLocation(state->program, "tex");
}
void create_background_buffers(background_t *state)
{
// VAO is required for OpenGL 3+ when using VBO I believe
#ifndef RASPI
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
#endif
// Generate vertex buffer
glGenBuffers(1, &state->vbo);
// Generate element buffer
glGenBuffers(1, &state->ebo);
}
void create_background_vertices(background_t *state)
{
// Vertices: Pos(x,y) Tex(x,y)
// For simplicity only single vbo is generated and offset used as needed
// Background image dimensions in gl screen coordinates
float bg_width = 2.0*(state->background_width/(float)state->screen_width);
float bg_height = 2.0*(state->background_height/(float)state->screen_height);
float lower_left_x = -bg_width/2.0;
float lower_left_y = -bg_height/2.0;
float lower_right_x = lower_left_x + bg_width;
float lower_right_y = lower_left_y;
float upper_right_x = lower_right_x;
float upper_right_y = lower_right_y + bg_height;
float upper_left_x = lower_left_x;
float upper_left_y = lower_left_y + bg_height;
float vertices[] = {
// Full screen vertices
upper_left_x, upper_left_y, 0.0f, 0.0f, // Upper left
upper_right_x, upper_right_y, 1.0f, 0.0f, // Upper right
lower_right_x, lower_right_y, 1.0f, 1.0f, // Lower right
lower_left_x, lower_left_y, 0.0f, 1.0f // Lower left
};
printf("Screen resolution %d, %d\n", state->screen_width, state->screen_height);
printf("ul (%f,%f), ur (%f, %f), ll (%f, %f), lr (%f, %f)\n", upper_left_x, upper_left_y, upper_right_x, upper_right_y, lower_left_x, lower_left_y, lower_right_x, lower_right_y);
// Set buffer
glBindBuffer(GL_ARRAY_BUFFER, state->vbo);
// Fill buffer
glBufferData(GL_ARRAY_BUFFER, 3*4*4*sizeof(GLfloat), vertices, GL_STATIC_DRAW);
// Elements
GLubyte elements[] = {
2, 3, 0,
0, 1, 2
};
// Set buffer
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, state->ebo);
// Fill buffer
glBufferData(GL_ELEMENT_ARRAY_BUFFER, 2*3*sizeof(GLubyte), elements, GL_STATIC_DRAW);
}
void create_background_texture(background_t *state)
{
// Read in background PNG
unsigned error;
unsigned char* image;
unsigned width, height;
#ifdef RASPI
error = lodepng_decode32_file(&image, &width, &height, "SPH/images/inl_logo.png");
#else
error = lodepng_decode32_file(&image, &width, &height, "images/inl_logo.png");
#endif
if(error) printf("error %u: %s\n", error, lodepng_error_text(error));
state->background_width = state->screen_width/2.2;
state->background_height = state->screen_height/1.5;
printf("Background image loaded: %d x %d pixels\n", width, height);
// Generate texture
glGenTextures(1, &state->tex_uniform);
// Set texture unit 0 and bind texture
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, state->tex_uniform);
// Buffer texture
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, image);
// 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);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
// Create Mipmap
glGenerateMipmap(GL_TEXTURE_2D);
// Release image host memory
free(image);
}
void init_background(background_t *state, int screen_width, int screen_height)
{
// Set screen with/height in pixels
state->screen_width = screen_width;
state->screen_height = screen_height;
// Create program
create_backround_program(state);
// Generate buffers
create_background_buffers(state);
// Create texture from image
// Must be called before create_background_verticies
// so image dimensions known
create_background_texture(state);
// Set verticies
create_background_vertices(state);
}
void draw_background(background_t *state)
{
// Setup program
glUseProgram(state->program);
// Setup buffers
size_t vert_size = 4*sizeof(GL_FLOAT);
glBindBuffer(GL_ARRAY_BUFFER, state->vbo);
glVertexAttribPointer(state->position_location, 2, GL_FLOAT, GL_FALSE, vert_size, 0);
glEnableVertexAttribArray(state->position_location);
glVertexAttribPointer(state->tex_coord_location, 2, GL_FLOAT, GL_FALSE, vert_size,(void*)(2*sizeof(GL_FLOAT)));
glEnableVertexAttribArray(state->tex_coord_location);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, state->ebo);
// Disable Blend
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
// Setup texture
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, state->tex_uniform);
glUniform1i(state->tex_location, 0);
// Draw background
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, 0);
}