Shader.cpp

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/* Copyright (c) 2014-2017, ARM Limited and Contributors
 *
 * SPDX-License-Identifier: MIT
 *
 * 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 "Common.h"
#include "Shader.h"

#include <cstdio>
#include <cstdlib>

namespace MaliSDK
{
    /* Please see header for specification. */
    char* Shader::loadShader(const char *filename)
    {
        FILE *file = fopen(filename, "rb");

        ASSERT(file != NULL, "Cannot read shader file.");

        /* Seek end of file. */
        fseek(file, 0, SEEK_END);

        /* Record the size of the file for memory allocation. */
        long length = ftell(file);

        /* Seek start of file again. */
        fseek(file, 0, SEEK_SET);

        char *shader = (char *)calloc(length + 1, sizeof(char));

        ASSERT(shader != NULL, "Cannot allocate memory for shader source.");

        /* Read in the file */
        size_t numberOfBytesRead = fread(shader, sizeof(char), length, file);

        ASSERT(numberOfBytesRead == length, "An error ocurred while reading shader source.");

        shader[length] = '\0';

        fclose(file);

        return shader;
    }

    /* Please see header for specification. */
    void Shader::processShader(GLuint *shaderObjectIdPtr, const char *filename, GLint shaderType)
    {
        ASSERT(shaderObjectIdPtr != NULL,
               "NULL pointer used to store generated shader object ID.");

        ASSERT(shaderType == GL_FRAGMENT_SHADER || shaderType == GL_VERTEX_SHADER,
               "Invalid shader object type.");

        GLint       compileStatus = GL_FALSE;
        const char *strings[1]    = { NULL };

        /* Create shader and load into GL. */
        /* [Create shader object]*/
        *shaderObjectIdPtr = GL_CHECK(glCreateShader(shaderType));
        /* [Create shader object]*/
        /* [Load shader source] */
        strings[0]         = loadShader(filename);
        /* [Load shader source] */

        /* [Attach shader source] */
        GL_CHECK(glShaderSource(*shaderObjectIdPtr, 1, strings, NULL));
        /* [Attach shader source] */

        /* Clean up shader source. */
        free((void *)(strings[0]));
        strings[0] = NULL;

        /* Try compiling the shader. */
        
        /* [Compile a shader] */
        GL_CHECK(glCompileShader(*shaderObjectIdPtr));
        /* [Compile a shader] */

        /* [Get compilation status] */
        GL_CHECK(glGetShaderiv(*shaderObjectIdPtr, GL_COMPILE_STATUS, &compileStatus));
        /* [Get compilation status] */

        /* Dump debug info (source and log) if compilation failed. */
        if (compileStatus != GL_TRUE)
        {
            char *debugSource = NULL;
            char *errorLog    = NULL;
            GLint length;

            /* Get shader source. */
            GL_CHECK(glGetShaderiv(*shaderObjectIdPtr, GL_SHADER_SOURCE_LENGTH, &length));

            debugSource = (char*) malloc(length);

            if (debugSource != NULL)
            {
                GL_CHECK(glGetShaderSource(*shaderObjectIdPtr, length, NULL, debugSource));

                LOGE("Debug source START:\n%s\nDebug source END\n\n", debugSource);

                free(debugSource);

                debugSource = NULL;
            }

            /* Now get the info log. */
            GL_CHECK(glGetShaderiv(*shaderObjectIdPtr, GL_INFO_LOG_LENGTH, &length));

            errorLog = (char*) malloc(length);

            if (errorLog != NULL)
            {
                GL_CHECK(glGetShaderInfoLog(*shaderObjectIdPtr, length, NULL, errorLog));

                LOGE("Log START:\n%s\nLog END\n\n", errorLog);

                free(errorLog);

                errorLog = NULL;
            }
        }

        ASSERT(compileStatus == GL_TRUE, "Shader compilation FAILED!");
    }
}