multi_tex.c

/*
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 <assert.h>

#include "multi_tex.h"
#include "ogl_utils.h"
#include "stdlib.h"
#include "fractal.h"

#define USE_MIPMAP 1

void create_textures(texture_t *state, FRAC_INFO *frac_left, FRAC_INFO *frac_right)
{
    int i,j,k;
    GLubyte *pixels;

    state->tex_width[LEFT] = frac_left->num_cols;
    state->tex_height[LEFT] = frac_left->num_rows;

    state->tex_width[RIGHT] = frac_right->num_cols;
    state->tex_height[RIGHT] = frac_right->num_rows;

    size_t pixel_bytes;
    pixel_bytes = state->tex_width[LEFT]*state->tex_height[LEFT]*sizeof(GLubyte)*frac_left->channels;
 
    // Left fractal
    pixels = malloc(pixel_bytes);

     // Pixel packing
    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    // Generate texture
    glGenTextures(NUM_TEXTURES, state->textures);
    // Set sampler
    glActiveTexture(GL_TEXTURE0);
 
   
    // Initialize left texture to black
    for(i=0; i<state->tex_height[LEFT]; i++) {
        for(j=0; j<state->tex_width[LEFT]; j++) {
            for(k=0; k<frac_left->channels; k++) {
                pixels[(i*state->tex_width[LEFT] + j)*frac_left->channels + k] = 255;
            }
        }
    }
 
    // Bind texture
    glBindTexture(GL_TEXTURE_2D, state->textures[LEFT]);

    // Load texture
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, state->tex_width[LEFT], state->tex_height[LEFT], 0, GL_RGB, GL_UNSIGNED_BYTE, pixels);

    // Set filtering modes
    #if !(USE_MIPMAP)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    #else
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    #endif
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);

    #if USE_MIPMAP
    // Generate mipmap
    glGenerateMipmap(GL_TEXTURE_2D);
    #endif

    free(pixels);

    // Right fractal
    pixel_bytes = state->tex_width[RIGHT]*state->tex_height[RIGHT]*sizeof(GLubyte)*frac_right->channels; 
    pixels = malloc(pixel_bytes);

    // Initialize right texture to white
    for(i=0; i<state->tex_height[RIGHT]; i++) {
        for(j=0; j<state->tex_width[RIGHT]; j++) {
            for(k=0; k<frac_right->channels; k++) {
                pixels[(i*state->tex_width[RIGHT] + j)*frac_right->channels + k] = 0;
            }
        }
    }
 
    // Bind texture
    glBindTexture(GL_TEXTURE_2D, state->textures[1]);

    // Load texture
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, state->tex_width[RIGHT], state->tex_height[RIGHT], 0, GL_RGB, GL_UNSIGNED_BYTE, pixels);

    #if USE_MIPMAP
    // Generate mipmap
    glGenerateMipmap(GL_TEXTURE_2D);
    #endif

    // Set filtering modes
    #if !(USE_MIPMAP)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    #else
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    #endif

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);


    #if USE_MIPMAP
    // Generate mipmap
    glGenerateMipmap(GL_TEXTURE_2D);
    #endif

    // Free pixels
    free(pixels);

}

void update_texture_rows(texture_t *state, int fractal, GLsizei start_row, GLuint num_rows, GLubyte *row_pixels)
{
    glBindTexture(GL_TEXTURE_2D, state->textures[fractal]);

    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, start_row, state->tex_width[fractal], num_rows, GL_RGB, GL_UNSIGNED_BYTE, row_pixels);

    #if USE_MIPMAP
    glGenerateMipmap(GL_TEXTURE_2D);
    #endif
}

// GLUE between outside world and textures - still requires state which I don't like
void update_fractal_rows(texture_t *state, int fractal, unsigned int start_row, unsigned int num_rows, unsigned char *row_pixels)
{
   update_texture_rows(state, fractal, (GLsizei)start_row, (GLsizei)num_rows, (GLubyte*)row_pixels);
   // Draw textures
   draw_textures(state);
}

void create_vertices(texture_t *state)
{
    // Vertices: Pos(x,y) Tex(x,y)
    // For simplicity only single vbo is generated and offset used as needed
    float vertices[] = {
        // Image 0 vertices
        -1.0f,   1.0f, 0.0f, 0.0f, // Top left
        -0.005f, 1.0f, 1.0f, 0.0f, // Top right
        -0.005f,-1.0f, 1.0f, 1.0f, // Bottom right
	-1.0f,  -1.0f, 0.0f, 1.0f,  // Bottom left
        // Image 1 vertices
         0.005f, 1.0f, 0.0f, 0.0f, // Top left
         1.0f,   1.0f, 1.0f, 0.0f, // Top right
         1.0f,  -1.0f, 1.0f, 1.0f, // Bottom right
	 0.005f,-1.0f, 0.0f, 1.0f,  // Bottom left
         // Full screen vertices
        -1.0f,  1.0f, 0.0f, 0.0f, // Top left
         1.0f,  1.0f, 1.0f, 0.0f, // Top right
         1.0f, -1.0f, 1.0f, 1.0f, // Bottom right
	-1.0f, -1.0f, 0.0f, 1.0f  // Bottom left
    };

    // 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);
    // 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
    };
    // Generate element buffer
    glGenBuffers(1, &state->ebo);
    // 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_shaders(texture_t *state)
{
    // Compile vertex shader
    GLuint vertex_shader = glCreateShader(GL_VERTEX_SHADER);
    #ifdef RASPI
        compile_shader(vertex_shader, "PiBrot/shaders/texture_es.vert");
    #else
        compile_shader(vertex_shader, "shaders/texture.vert");
    #endif

    // Compile fragment shader
    GLuint frag_shader = glCreateShader(GL_FRAGMENT_SHADER);
    #ifdef RASPI
        compile_shader(frag_shader, "PiBrot/shaders/texture_es.frag");
    #else
        compile_shader(frag_shader, "shaders/texture.frag");
    #endif

    // Create shader program
    state->program = glCreateProgram();
    glAttachShader(state->program, vertex_shader);
    glAttachShader(state->program, frag_shader);

    // Link and use program
    glLinkProgram(state->program);
    glUseProgram(state->program);
    check();
   
    // Get position 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 show_left_tex_fullscreen(texture_t *state)
{
    // Size of each vertex in bytes
    size_t vert_size = 4*sizeof(GL_FLOAT);
    // Offset in our vertices array that the full screen vertices start
    size_t offset = 2*4*vert_size;

    // Draw left fractal
    glVertexAttribPointer(state->position_location, 2, GL_FLOAT, GL_FALSE, vert_size, (void*)offset);
    glEnableVertexAttribArray(state->position_location);
    glVertexAttribPointer(state->tex_coord_location, 2, GL_FLOAT, GL_FALSE, vert_size,(void*)offset+2*sizeof(GL_FLOAT));
    glEnableVertexAttribArray(state->tex_coord_location);
    glBindTexture(GL_TEXTURE_2D, state->textures[LEFT]);
    glUniform1i(state->tex_location, 0);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, 0);

   // Swap buffers
   swap_ogl(state->gl_state);

}

void show_right_tex_fullscreen(texture_t *state)
{
    // Size of each vertex in bytes
    size_t vert_size = 4*sizeof(GL_FLOAT);
    // Offset in our vertices array that the full screen vertices start
    size_t offset = 2*4*vert_size;

    // Draw left fractal
    glVertexAttribPointer(state->position_location, 2, GL_FLOAT, GL_FALSE, vert_size, (void*)offset);
    glEnableVertexAttribArray(state->position_location);
    glVertexAttribPointer(state->tex_coord_location, 2, GL_FLOAT, GL_FALSE, vert_size,(void*)offset+2*sizeof(GL_FLOAT));
    glEnableVertexAttribArray(state->tex_coord_location);
    glBindTexture(GL_TEXTURE_2D, state->textures[RIGHT]);
    glUniform1i(state->tex_location, 0);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, 0);

    // Swap buffers
    swap_ogl(state->gl_state);
}

void show_both_textures(texture_t *state)
{
    draw_textures(state);
    swap_ogl(state->gl_state);
}
*/

void draw_textures(texture_t *state)
{
    // Setup program
    glUseProgram(state->program);

    glClearColor(0.5f, 0.5f, 0.5f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);

    // Size of each vertex in bytes
    size_t vert_size = 4*sizeof(GL_FLOAT);

    glBindBuffer(GL_ARRAY_BUFFER, state->vbo);
    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, state->ebo);

    // Draw left fractal
    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);
    glBindTexture(GL_TEXTURE_2D, state->textures[LEFT]);
    glUniform1i(state->tex_location, 0);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, 0);

    // Draw right fractal
    // Offset in vertices array that right texture will use
    size_t offset = 4*vert_size; 
    glVertexAttribPointer(state->position_location, 2, GL_FLOAT, GL_FALSE, vert_size, (void*)offset);
    glEnableVertexAttribArray(state->position_location);
    glVertexAttribPointer(state->tex_coord_location, 2, GL_FLOAT, GL_FALSE, vert_size,(void*)(offset+2*sizeof(GL_FLOAT)));
    glEnableVertexAttribArray(state->tex_coord_location);
    glBindTexture(GL_TEXTURE_2D, state->textures[RIGHT]);
    glUniform1i(state->tex_location, 0);
    glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_BYTE, 0);
}