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Font refactor part 4: Thy Flesh Co- I mean, OpenGL

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Hard mode. Wound up debugging a weird issue for about half an hour.
Turns out you don't need to reset the matrix when you switch
framebuffer target? I don't really know how that works.

Anyway, yay font rendering is in the OpenGL backend now.
This commit is contained in:
Clownacy 2019-07-23 20:05:38 +01:00
parent e2054918a6
commit 8aad8a6628
1 changed files with 112 additions and 25 deletions
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137
src/Backends/Rendering/OpenGL2.cpp
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@ -18,6 +18,13 @@ typedef struct Backend_Surface
unsigned char *pixels;
} Backend_Surface;
typedef struct Backend_Glyph
{
GLuint texture_id;
unsigned int width;
unsigned int height;
} Backend_Glyph;
static SDL_Window *window;
static SDL_GLContext context;
static GLuint colour_key_program_id;
@ -88,6 +95,8 @@ BOOL Backend_Init(SDL_Window *p_window)
// glLoadIdentity();
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
@ -228,14 +237,7 @@ void Backend_Blit(Backend_Surface *source_surface, const RECT *rect, Backend_Sur
// Point our framebuffer to the destination texture
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, destination_surface->texture_id, 0);
// The matrix needs resetting to fit the dimensions of the destination texture
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, destination_surface->width, 0.0, destination_surface->height, 1.0, -1.0);
BlitCommon(source_surface, rect, x, y, colour_key);
glPopMatrix();
}
void Backend_BlitToScreen(Backend_Surface *source_surface, const RECT *rect, long x, long y, BOOL colour_key)
@ -268,14 +270,7 @@ void Backend_ColourFill(Backend_Surface *surface, const RECT *rect, unsigned cha
// Point our framebuffer to the destination texture
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface->texture_id, 0);
// The matrix needs resetting to fit the dimensions of the destination texture
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, surface->width, 0.0, surface->height, 1.0, -1.0);
ColourFillCommon(rect, red, green, blue);
glPopMatrix();
}
void Backend_ColourFillToScreen(const RECT *rect, unsigned char red, unsigned char green, unsigned char blue)
@ -291,24 +286,116 @@ void Backend_ScreenToSurface(Backend_Surface *surface, const RECT *rect)
// Point our framebuffer to the destination texture
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface->texture_id, 0);
// The matrix needs resetting to fit the dimensions of the destination texture
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, surface->width, 0.0, surface->height, 1.0, -1.0);
BlitCommon(&framebuffer_surface, rect, rect->left, rect->top, FALSE);
glPopMatrix();
}
void Backend_DrawText(Backend_Surface *surface, FontObject *font, int x, int y, const char *text, unsigned long colour)
BOOL Backend_SupportsSubpixelGlyph(void)
{
// Soon
return FALSE; // Per-component alpha is available as an extension, but I haven't looked into it yet
}
void Backend_DrawTextToScreen(FontObject *font, int x, int y, const char *text, unsigned long colour)
Backend_Glyph* Backend_LoadGlyph(const unsigned char *pixels, unsigned int width, unsigned int height, int pitch, unsigned short total_greys, unsigned char pixel_mode)
{
// Soon
Backend_Glyph *glyph = (Backend_Glyph*)malloc(sizeof(Backend_Glyph));
if (glyph == NULL)
return NULL;
unsigned char *buffer = (unsigned char*)malloc(width * height * 4);
switch (pixel_mode)
{
// FONT_PIXEL_MODE_LCD is unsupported
case FONT_PIXEL_MODE_GRAY:
for (unsigned int y = 0; y < height; ++y)
{
const unsigned char *source_pointer = pixels + y * pitch;
unsigned char *destination_pointer = buffer + y * width * 4;
for (unsigned int x = 0; x < width; ++x)
{
*destination_pointer++ = 0xFF;
*destination_pointer++ = 0xFF;
*destination_pointer++ = 0xFF;
*destination_pointer++ = (unsigned char)(pow((double)*source_pointer++ / (total_greys - 1), 1.0 / 1.8) * 255.0);
}
}
break;
case FONT_PIXEL_MODE_MONO:
for (unsigned int y = 0; y < height; ++y)
{
const unsigned char *source_pointer = pixels + y * pitch;
unsigned char *destination_pointer = buffer + y * width * 4;
for (unsigned int x = 0; x < width; ++x)
{
*destination_pointer++ = 0xFF;
*destination_pointer++ = 0xFF;
*destination_pointer++ = 0xFF;
*destination_pointer++ = *source_pointer++ ? 0xFF : 0;
}
}
break;
}
glGenTextures(1, &glyph->texture_id);
glBindTexture(GL_TEXTURE_2D, glyph->texture_id);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glyph->width = width;
glyph->height = height;
free(buffer);
return glyph;
}
void Backend_UnloadGlyph(Backend_Glyph *glyph)
{
glDeleteTextures(1, &glyph->texture_id);
free(glyph);
}
static void DrawGlyphCommon(Backend_Glyph *glyph, long x, long y, const unsigned char *colours)
{
// Disable colour-keying
glUseProgram(0);
glBindTexture(GL_TEXTURE_2D, glyph->texture_id);
glBegin(GL_QUADS);
glColor3f(colours[0] / 255.0f, colours[1] / 255.0f, colours[2] / 255.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex2f((GLfloat)x, (GLfloat)y);
glTexCoord2f(1.0f, 0.0f);
glVertex2f((GLfloat)x + glyph->width, (GLfloat)y);
glTexCoord2f(1.0f, 1.0f);
glVertex2f((GLfloat)x + glyph->width, (GLfloat)y + glyph->height);
glTexCoord2f(0.0f, 1.0f);
glVertex2f((GLfloat)x, (GLfloat)y + glyph->height);
glEnd();
}
void Backend_DrawGlyph(Backend_Surface *surface, Backend_Glyph *glyph, long x, long y, const unsigned char *colours)
{
// Point our framebuffer to the destination texture
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface->texture_id, 0);
DrawGlyphCommon(glyph, x, y, colours);
}
void Backend_DrawGlyphToScreen(Backend_Glyph *glyph, long x, long y, const unsigned char *colours)
{
// Point our framebuffer to the screen texture
glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, framebuffer_surface.texture_id, 0);
DrawGlyphCommon(glyph, x, y, colours);
}
void Backend_HandleDeviceLoss(void)